Vitamin B12 and plant-based diets

It’s not uncommon to read newspaper headlines about nutrient deficiencies from vegetarian or vegan diets – people love good news about their bad habits.

When you scratch beneath the surface of such headlines, though, it usually becomes obvious that the individual concerned wasn’t eating enough food in general or was suffering from another health condition.

Nevertheless, vitamin B12 deficiency is often quoted as a reason for avoiding plant-based or vegan diets.

Jane Philpott Cooking for Health

Plant-based dishes by Jane Philpott at

So is this justified?

Please read on if you’re interested in finding out.

What is vitamin B12 and why do you need it?

Vitamin B12, also called cobalamin, is a cobalt-containing water-soluble B vitamin.

Vitamin B12

It’s one of eight B vitamins, all of which help the body convert food (carbohydrates) into fuel (glucose), which is used to produce energy.

These B vitamins, often referred to as B complex vitamins, also help the body use fats and protein. B complex vitamins are needed for healthy skin, hair, eyes, and liver. They also help the nervous system function properly.

Vitamin B12 is an especially important vitamin for maintaining healthy nerve cells, and it helps in the production of DNA and RNA, the body’s genetic material.

Vitamin B12 also works closely with vitamin B9, also called folate or folic acid, to help make red blood cells and to help iron work better in the body.

Folate and B12 work together to produce S-adenosylmethionine (SAMe), a compound involved in immune function and mood.

Vitamins B12, B6, and B9 work together to control blood levels of the amino acid homocysteine. High levels of homocysteine are associated with a number of chronic health conditions, including heart disease, dementia and multiple sclerosis. Researchers aren’t sure whether homocysteine is a cause of these conditions or just a marker that indicates someone may have such a condition.

Vitamin B12, or cobalamin, belongs to a family of closely related chemicals, called corrinoids, some of which are biologically inactive in humans. The inactive versions are sometimes referred to as pseudovitamin B12 (1).

The two vitamin B12 coenzymes known to be metabolically active in mammalian tissues are 5-deoxyadenosylcobalamin and methylcobalamin.

How much vitamin B12 do you need?

Dietary guidelines for intake of vitamin B12 vary from country to country.

In the US, Australia and New Zealand the guideline is 2.4 µg (micrograms) per day; in the UK it’s 1.5 µg per day; and in the EU it’s 1 µg per day.

On average the guideline is about 2 µg (micrograms) per day for adults and <1 µg per day for children.

One microgram is one-millionth of a gram, so only trace amounts of this vitamin are required.

What happens if you don’t consume enough vitamin B12?

Symptoms of vitamin B12 deficiency include a type of anaemia, called megaloblastic or macrocystic anaemia, which results from inhibition of DNA synthesis during production of red blood cells. The red blood cells grow larger than normal and are less able to carry oxygen.

B12 deficiency anaemia

Megaloblastic anaemia is fatal if untreated, but can usually be reversed with B12 injections and sometimes with B12 tablets (2).

Anaemia caused by a lack of vitamin B12 can result in symptoms which include:
• Extreme tiredness or fatigue
• A lack of energy or lethargy
• Being out of breath
• Feeling faint
• Headache
• Ringing in the ears (tinnitus)
• Lack of appetite

More specific symptoms linked to a lack of vitamin B12 include:
• Yellowing of the skin
• Sore, red tongue
• Mouth ulcers
• Changes or loss of some sense of touch
• Feeling less pain
• Walking problems
• Vision problems
• Mood changes, irritability, depression or psychosis
• Symptoms of dementia

Rarely, vitamin B12 deficiency can result in irreversible damage to the nervous system.

Over the last decade or so, researchers have strongly implicated the toxic amino acid homocysteine in a variety of disease states.

Homocysteine tends to accumulate in the body whenever vitamin B12 gets deficient, and this accumulation has been linked with increased risk of Alzheimer’s and other neuropsychiatric disease (3-5), cardiovascular disease (6,7) chronic fatigue syndrome and fibromyalgia (8) multiple sclerosis (9) and kidney disease (10), among other conditions.

Folic acid deficiency can also lead to increased homocysteine levels. This is because folate and vitamin B12, in their active ‘coenzyme’ forms, are both necessary cofactors for the enzymatic conversion of homocysteine to methionine.

Until recently it was thought that the availability of folate was the most important determinant of the body’s ability to re-methylate homocysteine.

New research has revealed that vitamin B12 is more important for homocysteine disposal than previously believed (9,11-13).

For example, a study conducted among dialysis patients with kidney failure showed that a monthly injection of vitamin B12 plus conventional oral folate was more effective than high-dose folate without vitamin B12 in lowering elevated homocysteine (11).

Where does vitamin B12 come from?

Vitamin B12 is synthesised only by certain bacteria, and is not made by either plants or animals.

Ruminants, like cows, goats, sheep, giraffes, llamas, buffalo, and deer, are unique in that bacteria in their stomachs (rumen) synthesise vitamin B12, which then moves down and is absorbed by their small intestines.


Animal tissues store bacteria-synthesised vitamin B12, which can then be passed along the food chain by animals eating other animals (14).

The human gut also contains vitamin B12-synthesising bacteria, living from the mouth to the anus (15).

In humans, most intestinal vitamin B12 is produced in our large intestine, or colon, which is home to 4 trillion bacteria per cm3 of faeces.

Unfortunately, most vitamin B12 is absorbed in the small intestine, which is upstream of the large intestine, so the B12 produced in the latter is largely unavailable to us, unless we eat poop, which is obviously not recommended.

Faeces of cows, chickens and sheep also contain active vitamin B12.

In the past, people lived in close contact with farm animals. Animal manure was used to fertilise the land and people ate vegetables straight from the soil, so they would naturally have consumed small amounts of vitamin B12, even if they did not eat animal products.

Traditional agriculture

Nowadays, most people have little or no contact with farm animals and consume vegetables which are industrially washed and disinfected before reaching supermarkets. In addition, our living environments are heavily sanitised.

These changes to human lifestyle, whilst beneficial in many respects, have likely led to a reduction in naturally occurring intake of vitamin B12.

Though it’s generally stated that people don’t benefit much from the synthesis of vitamin B12 in the human gut because most is made in the colon, there is evidence from healthy subjects that at least two groups of organisms in the small intestine, Pseudomonas and Klebsiella sp., may synthesise significant amounts of vitamin B12 which can be actively absorbed in the presence of intrinsic factor (16).

Foods derived from animals – meat, milk, eggs, fish and shellfish – are thus the major dietary sources of vitamin B12; the richest natural sources are liver and kidney.

Vitamin B12 content of food

Animal-derived sources of vitamin B12

Eating a diet rich in animal products will, however, give you a one-in-two chance of dying prematurely from a heart attack or stroke; a one-in-seven chance of breast cancer or a one-in-six chance of prostate cancer (17). Such a diet also results in obesity, diabetes, osteoporosis, constipation, indigestion, and arthritis (18).

So what can you do to avoid vitamin B12 deficiency if you don’t want to eat animals?

Vitamin B12 deficiency and plant-based diets

If you’re on a strict vegan diet – no meat, fish, dairy, or eggs – you have a low risk of vitamin B12 deficiency, which increases gradually with time, as body reserves of B12 are used up.

On average, for someone raised on the Western diet, about 2 to 5 milligrams of B12 are stored, mostly in the liver. It’s been calculated that most people have a 3 to 6 year reserve of this vital nutrient (19).

Conservation of B12 by the body boosts the time this supply lasts by 10-fold.

It’s estimated to take at least 20-30 years to deplete body reserves of vitamin B12, in the unlikely event of zero vitamin B12 intake during this period, as there are efficient mechanisms for re-absorbing and re-circulating B12 between the liver and intestines (20).

Vitamin B12 deficiency is more common in older people and affects around one in 10 over 75s (21).

Elderly people

Pregnant women on a strict vegan diet are also at a higher risk of B12 deficiency (22).

Blood levels of vitamin B12 can be measured directly and are a means to help diagnose deficiency.

Values above 150 pg/ml (picograms per millilitre) are considered normal, and levels below 80 pg/ml represent unequivocal B12 deficiency (23).

Absorption of vitamin B12

Vitamin B12 deficiency most commonly occurs due to health problems with the stomach and intestine, caused by autoimmune diseases, ulcers, parasites or surgery, rather than to a lack of B12 in the diet (24).

Vitamin B12 is the only nutrient that requires a cofactor for efficient absorption.

The cells of the stomach produce a substance, called intrinsic factor, which combines with vitamin B12 released from food, after acidic digestion in the stomach (25).

small intestine, colon

This intrinsic factor-B12 complex then travels to the end of the small intestine, called the ileum, where it’s actively absorbed.

If intrinsic factor isn’t produced due to damage to the parietal cells of the stomach, for example caused by pernicious anaemia, vitamin B12 cannot be absorbed and does not reach the cells where it’s needed.

Vitamin B12 can cross the intestine by passive absorption, but this mechanism does not use intrinsic factor; as a result, it’s 1000 times less efficient (26).

Plant-based sources of vitamin B12

As highlighted above, vitamin B12 is made only by certain bacteria and not by plants or animals.

Some plant-based foods have been shown to contain vitamin B12, due to their association with bacteria that synthesise it.

I’ve already mentioned that different forms of vitamin B12 exist, some of which are biologically inactive and are referred to as pseudovitamin B12.

When reviewing the scientific literature, it’s important to be clear if a food source contains active or inactive vitamin B12, as well as how reliable it is as a source of vitamin B12.

Consuming inactive or pseudovitamin B12 will not benefit your health in the slightest.

Growing vegetables in organic cow manure

Some reports in the literature suggest that adding an organic fertiliser such as cow manure significantly increases the vitamin B12 content of vegetables such as spinach leaves, i.e., approximately 0.14 μg per 100 g fresh weight (27).

organic vegetables

This sounds potentially exciting but research indicates that most organic fertilisers, particularly those made from animal manures, contain considerable amounts of the inactive form – pseudovitamin B12 (28).

It’s also worth pointing out that you’d have to eat 3 lb (1.4 kg) of this organically grown spinach to obtain the guideline daily amount of vitamin B12.


A fermented soybean-based food called tempeh has been shown to contain a considerable amount of biologically active vitamin B12 (0.7–8.0 μg per 100 g) (29).

Tempeh originated in Indonesia and is made from whole soybeans, which are soaked, de-hulled, and partly cooked. They are then fermented for 24 to 36 hours at 30°C with the spores of a fungus, Rhizopus oligosporus or Rhizopus oryzae, forming a solid block meshed together with a white mycelium.

Soy products

Different batches of tempeh may vary substantially in the amount of vitamin B12 they contain, so this is not necessarily a reliable source.

Cooked tempeh can be eaten alone, or used in chilli, stir fries, soups, salads, sandwiches, and stews. Tempeh’s complex flavour has been described as nutty, meaty, and mushroom-like. It freezes well, and is now commonly available in many western supermarkets, as well as in ethnic markets and health food stores.

Tea leaves

Vitamin B12 is also found in various types of tea leaves (approximately 0.1 to 1.2 μg vitamin B12 per 100 g dry weight) (30).

For example, vitamin B12-deficient rats were fed a Japanese fermented black tea (Batabata-cha) drink for 6 weeks, and their B12 deficiency was reduced compared with control rats (31).

Consumption of 1–2 litres of the fermented tea drink (typical regular consumption in Japan), which is equivalent to 20 to 40 ng of vitamin B12, is not however sufficient to meet the guideline daily intake of 2 μg per day for adult humans.

japanese tea ceremony

It’s important to note that Japanese teas such as Batabata-cha are made in a different way from the Indian black teas commonly consumed in Europe and the US, so the results are not applicable to tea-drinking in general.

You can buy Batabata-cha online.


Mushrooms are fungi rather than plants. Various species of mushroom have been analysed for active vitamin B12 content.

Several wild edible mushroom species popular in Europe were found to contain zero or trace levels (approximately 0.09 μg per 100 g dry weight) of vitamin B12: porcini mushrooms (Boletus sp.), parasol mushrooms (Macrolepiota procera), oyster mushrooms (Pleurotus ostreatus), and black morels (Morchella conica).

In contrast, the fruiting bodies of black trumpet (Craterellus cornucopioides) and golden chanterelle (Cantharellus cibarius) contained higher levels of active vitamin B12 (1.09–2.65 μg per 100 g dry weight) (32).

High levels of active vitamin B12 were detected in the commercially available dried shiitake mushroom fruiting bodies (Lentinula edodes), with the average measured at approximately 5.61 μg per 100g dry weight (33).

mushrooms containing vitamin B12

Shiitake mushrooms

Shiitake mushrooms can be added to soups and stir-fries, steamed, or sautéed with onions and other vegetables to create a wide variety of nutritious and delicious dishes.

Please click here for a recipe for mushroom stroganoff – a plant-based, vegan recipe using shiitake mushrooms and nutritional yeast, which contains 112 per cent of the recommended daily intake of vitamin B12 per serving.

Vegan, plant-based recipe for mushroom stroganoff

Mushroom Strogonoff

Sea vegetables (seaweed)

Nori – the dried green and purple lavers commonly used to make sushi (Enteromorpha sp. and Porphyra sp., respectively) – contain substantial amounts of the biologically active form of vitamin B12 (approximately 63.6 μg per 100 g dry weight and 32.3 μg per 100 g dry weight, respectively) (34).

Please click here for a recipe for vegetable sushi nori.

How to make vegetable sushi rolls

Vegetable sushi nori

A nutritional analysis of six vegan children who had consumed vegan diets including brown rice and dried purple laver (nori) for 4 to 10 years suggested that the regular consumption of nori may prevent vitamin B12 deficiency (35).

Other edible seaweeds contain zero or only trace levels of vitamin B12.

Foods fortified with vitamin B12

Vitamin B12 can be obtained from many everyday food items that are fortified, such as veggie burger and sausage mixes, yeast extracts, vegetables stocks, margarines, breakfast cereals and soya milks.

Many of these food products are heavily processed, so please read the labels to check what you’re consuming.

See the table below for a guide to how much vitamin B12 is contained in a range of these foods.

foods fortified with B12

Sources: McCance and Widdowson (36) and manufacturers’ product information


Vitamin B12 supplements

Vitamin B12 is found in almost all multivitamins, often referred to by its scientific name, cobalamin.

Dietary supplements that contain only vitamin B12, or vitamin B12 with nutrients such as folic acid and other B vitamins, are also available.


Vitamin B12 is also available in sublingual forms (which are dissolved under the tongue). There is no evidence that sublingual forms are better absorbed than pills that are swallowed.

A prescription form of vitamin B12 can be administered as an injection. This is usually used to treat vitamin B12 deficiency.

Vitamin B12 is also available as a prescription medication in nasal gel form (for use in the nose).

Forms of vitamin B12 in supplements

As a food additive and a supplement pill, vitamin B12 is usually found in the form cyanocobalamin, which is cobalamin bonded to a cyanide ligand.

Cyanocobalamin does not occur in nature, but is produced semi-synthetically from bacterial hydroxycobalamin and then used in many pharmaceuticals and supplements, and as a food additive, because of its stability and lower production cost.

Cyanocobalamin was originally produced by accident and at first remained unrecognised.

Historically, during the production process, activated charcoal columns were used to purify vitamin B12 synthesised by bacteria.

Cyanide is naturally present in activated charcoal, and hydroxycobalamin, which has great affinity for cyanide, picks it up, and is changed to cyanocobalamin.

Nowadays, industrial production of cyanocobalamin begins with fermentation of the bacteria Propionibacterium shermanii or Pseudomonas denitrificans; these strains make about 100 000 times more vitamin B12 than they need for their own growth (37,38).

This process yields a mixture of methyl-, hydroxy-, and adenosylcobalamin.

These compounds are converted to cyanocobalamin by addition of potassium cyanide in the presence of sodium nitrite and heat.

In the body, cyanocobalamin is converted to the human physiological forms methylcobalamin and adenosylcobalamin, leaving behind the cyanide, albeit in minimal concentration.

Is cyanocobalamin toxic?

On many natural health sites on the internet, you’ll come across warnings about the alleged toxicity of cyanocobalamin due to the production of cyanide during its metabolism.

Is this fact or fiction?

Cyanides can occur naturally or be man-made and it’s true that many are powerful and rapid-acting poisons.

Hydrogen cyanide (HCN), which is a gas, and the simple cyanide salts (sodium cyanide and potassium cyanide) are common examples of cyanide compounds.

Certain bacteria, fungi, and algae can produce cyanide, and cyanide is found naturally in a number of foods and in over 2650 plants (39-41).

In certain plant foods, including almonds, millet sprouts, lima beans, soy, spinach, bamboo shoots, and cassava roots (which are a major source of food in tropical countries), cyanides occur naturally as part of sugars and other compounds. The sugar-cyanide complexes are sometimes referred to as cyanogenic glycosides.

cyanogenic glycosides in food

Cyanide in food plants (39-41)

When the plant is damaged or chewed a chemical reaction occurs in the harmed cell and the cyanide is released as a natural defence.

The human body can detoxify a small amount of cyanide in the liver through a pathway involving a molecule called thiosulfate.

Researchers have estimated the rate of detoxification of cyanide in humans at between 1µg (micrograms) and 17µg per kg per minute in the absence of antidotes (42).

Poisoning occurs when there is not enough thiosulfate to neutralise all the cyanide.

At low toxic concentrations cyanide can provoke nausea, vomiting, general weakness and dizziness.

At lethal concentrations, cyanide inhibits cellular respiration, causing cardiac arrest and rapid death.

A lethal dose to humans is thought to be 98 mg (milligrams) in one day, with a lowest documented lethal dose of 37.8 mg (0.54mg/kg body weight) (43).

The amount of cyanide in 1000 µg (1000 micrograms or 1 milligram) of cyanocobalamin is 20 µg (micrograms), or 0.05 per cent of the lower level thought to be harmful.

To put this in context, the inhaled smoke from one cigarette contains 40 to 100 µg cyanide (44).

Plants contain between 0.01 to 5 µg hydrogen cyanide (HCN) per 1000 µg (mg) (39-41).

So if you ate, say, I tablespoon (10 g) of flax meal, you’d potentially consume 3600 µg HCN, which is obviously much more than the 2 µg cyanide from eating a 1000 µg cyanocobalmin pill.

cyanogenic glycosides

Food plants containing cyanide


The safety and effectiveness of the cyanocobalamin “cyanide complex” for treating neurologic problems has, however, been questioned; therefore, other forms, such as methylcobalamin and hydroxycobalamin are also used for the prevention and treatment of B12-related conditions (45).

Hydroxycobalamin is typically used in vitamin B12 injections but is reported to be less stable than cyanocobalamin.

Chemical stability studies show that, at worst, a solution of hydroxycobalamin in pH 4.3 acetate buffer will retain at least 90 per cent of claimed cobalamin at 30°C for 170 weeks (46).

If you’d prefer to avoid consuming even small amounts of cyanide every day, you can also buy liquid supplements for oral use containing hydroxycobalamin.

Existing evidence does not suggest any substantial differences among forms with respect to absorption or bioavailability.

Are ‘natural’ vitamin B12 supplements better?

High levels of vitamin B12 are described on the nutritional labels of dietary supplements that contain edible blue-green algae (cyanobacteria) such as Spirulina, Aphanizomenon, and Nostoc.

Although substantial amounts of vitamin B12 are detected in these commercially available supplements, lab studies show that these supplements often contain large amounts of pseudovitamin B12, which has no biological effect (47).

chlorella supplements

Chlorella tablets (eukaryotic microalgae Chlorella sp.) used in human food supplements contain biologically active vitamin B12 (48), however, contents vary substantially between commercially available Chlorella tablets (from zero to several hundred μg of vitamin B12 per 100 g dry weight), so these may be an unreliable source (33).

Can vitamin B12 supplements interact with medicines?

Vitamin B12 can interact or interfere with medicines that you take, and in some cases, medicines can lower vitamin B12 levels in the body.

Here are several examples of medicines that can interfere with the body’s absorption or use of vitamin B12:
• Chloramphenicol (Chloromycetin®), an antibiotic that is used to treat certain infections.
• Proton pump inhibitors, such as omeprazole (Prilosec®) and lansoprazole (Prevacid®), that are used to treat acid reflux and peptic ulcer disease.
• Histamine H2 receptor antagonists, such as cimetidine (Tagamet®), famotidine (Pepcid®), and ranitidine (Zantac®), that are used to treat peptic ulcer disease.
• Metformin, a drug used to treat diabetes.

You are advised to tell your doctor, pharmacist, and other health care providers about any dietary supplements and medicines you take. They can tell you if those dietary supplements might interact or interfere with your prescription or over-the-counter medicines or if the medicines might interfere with how your body absorbs, uses, or breaks down nutrients.

What dose of vitamin B12 supplement should I take?

As noted above, official dietary guidelines for intake of vitamin B12 are approximately 2 µg (micrograms) per day for adults and less than 1 µg per day for children.

Most vitamin B12 supplements sold contain 500 to 5000 µg (micrograms) per pill, which is between 250 and 2500 fold higher than the guideline dietary intake.

The body’s ability to absorb vitamin B12 from dietary supplements is largely limited by the capacity of intrinsic factor produced in the stomach.

Studies have shown that absorption of physiological doses of vitamin B12 is limited to approximately 1.5 to 2 µg per dose or meal, due to saturation of the active uptake system (49).

Regardless of dose, approximately 1 per cent of vitamin B12 is absorbed by passive diffusion and consequently this process becomes quantitatively important at high levels of exposure (50,51).

Bioavailability for those who need vitamin B12 the most is especially poor, because of weaknesses in their stomach and intestines, affecting either classical intrinsic factor-mediated absorption or passive B12 absorption.

In healthy subjects, bioavailability of cyanocobalamin has been shown to be approximately 5 per cent of the oral dose (52).

Evidence shows that many elderly persons respond poorly to daily oral doses under 500 µg, with bioavailability of 2 per cent or less (53,54).

Those least in need of vitamin B12 usually have normal absorption and are thus at greatest risk for whatever unknown adverse effects of high-dose supplementation or fortification might emerge, such as potential effects of excess accumulation of cyanocobalamin (55).

That said, in 2000 the European Union Scientific Committee on Food concluded that no adverse effects have been associated with excess vitamin B12 intake from food or supplements in healthy individuals, and that vitamin B12 has a history of safe long-term use as a therapeutic agent given in high dosages (56).

In vitamin B12 replacement therapy oral dosages between 1-5 mg (milligrams) vitamin B12 are used, with no supportive evidence of adverse effects (56).


From reviewing the literature, it appears that elderly people suffering from vitamin B12 deficiency are either given injections of 1000 µg once per day for 10 days (after 10 days, the dose is changed to once weekly for four weeks, followed by once monthly for life); or oral doses of 125 to 2,000 micrograms daily for up to 2.5 years or longer, to ensure adequate amounts are reaching the bloodstream.

Otherwise healthy meat or fish eaters are unlikely to need supplements at all.

For healthy people on strict vegan or plant-based diets, who are not consuming fortified foods or foods naturally containing vitamin B12, one 500 µg pill per week or 5µg of a liquid formulation per day is likely to be adequate (57).

If you’re concerned about your vitamin B12 levels, please go and consult your physician or qualified healthcare provider. They’ll be able to arrange for blood tests to check:

  • whether you have a lower level of haemoglobin (a substance that transports oxygen) than normal
  • whether your red blood cells are larger than normal
  • the level of vitamin B12 in your blood
  • the level of folate in your blood

These tests can often help identify people with a possible vitamin B12 or folate deficiency, but they are not necessarily conclusive, because some people can have problems with normal levels of these vitamins, and others can have low levels despite having no symptoms.

This means it is very difficult to devise definitive criteria for the diagnosis of vitamin B12 or folate deficiency, and this is why it is important for your symptoms to be taken into account when a diagnosis is made.

I hope this post has helped to answer any questions you may have had about vitamin B12 – if you have any others, please write in the comments below.

dividing line

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33. Watanabe F, Yabuta, Y., Bito, T., & Teng, F. Vitamin B12-Containing Plant Food Sources for Vegetarians. Nutrients. 2014;6(5):1861–1873.
34. Watanabe F. TS, Katsura H., Masumder S.A., Abe K., Tamura Y., Nakano Y. Dried green and purple lavers (nori) contain substantial amounts of biologically active vitamin B12 but less of dietary iodine relative to other edible seaweeds. J. Agric. Food Chem. 1999;47:2341–2343.
35. H S. Serum vitamin B12 levels in young vegans who eat brown rice. J Nutr Sci Vitaminol (Tokyo). 1995;41(6):587-594.
36. Agency FS. McCance and Widdowsons the Composition of Food. 7th ed. London: Royal Society of Chemistry; 2014.
37. Spalla C GA, Garofano L, Ferni G. . Microbial production of vitamin B12. In: EJ V, ed. Biotechnology of vitamins, pigments and growth factors. New York: Elsevier Appl Science; 1989:257-284.
38. Kusel JP FY, Demain AL. . Betaine stimulation of vitamin B12 biosynthesis in Pseudomonas denitrificans may be mediated by an increase in activity of d-aminolaevulinic acid synthase. J Gen Microbiol. 1984;130:835-841.
39. Haque MR BJ. Total cyanide determination of plants and foods using the picrate and acid hydrolysis methods. Food chemistry. 2002;77(1):107-114.
40. Simeonova FP FL. Hydrogen cyanide and cyanides: Human health aspects. Geneva: World Health Organisation;2004.
41. Shragg TA AT, Fisher Jr CJ. Cyanide poisoning after bitter almond ingestion. Western Journal of Medicine. 1982;136(1):65-69.
42. Newhouse KaC, N. Toxicological review of hydrogen cyanide and cyanide salts. Washington DC: US Environmental Protection Agency;September 2010.
43. Safety) IIPoC. Hydrogen cyanide and cyanides: human health aspects. Geneva: World Health Organization;2004.
44. Fiskel J CC, and Eschenroeder A. . Exposure and risk assessment for cyanide. 1981.
45. AG. F. Hydroxocobalamin versus cyanocobalamin. J R Soc Med. 1996;89(11)(Nov):659.
46. Marcus AD, Stanley JL. Stability of the cobalamin moiety in buffered aqueous solutions of hydroxocobalamin. Journal of Pharmaceutical Sciences. 1964;53(1):91-94.
47. Watanabe F KH, Takenaka S, Fujita T, Abe K, Tamura Y, Nakatsuka T, Nakano Y. Pseudovitamin B(12) is the predominant cobamide of an algal health food, spirulina tablets. J Agric Food Chem. 1999;47(11):4736-4741.
48. Kittaka-Katsura H. FT, Watanabe F., Nakano Y. . Purification and characterization of a corrinoid-compound from chlorella tablets as an algal health food. J. Agric. Food Chem. 2002;50:4994–4997.
49. Minerals EGoVa. Report on safe upper levels for vitamins and minerals. LondonMay 2003.
50. Scott JM. Bioavailability of vitamin B12. European journal of clinical nutrition. 1997;51 (Suppl. 1):S49-S53.
51. Baik HWaR, R.M. Vitamin B12 deficiency in the elderly. Annual Review Nutrition. 1999;19:357-377.
52. Castelli MC, Wong DF, Friedman K, Riley MGI. Pharmacokinetics of Oral Cyanocobalamin Formulated With Sodium N-[8-(2-hydroxybenzoyl)amino]caprylate (SNAC): An Open-Label, Randomized, Single-Dose, Parallel-Group Study in Healthy Male Subjects. Clinical Therapeutics.33(7):934-945.
53. Eussen SJ dGL, Clarke R, et al. . Oral cyanocobalamin supplementation in older people with vitamin B12 deficiency: a dose-finding trial. Arch Intern Med. 2005;165(10)(May 23):1167-1172.
54. Hill MH, Flatley JE, Barker ME, et al. A vitamin B-12 supplement of 500 mug/d for eight weeks does not normalize urinary methylmalonic acid or other biomarkers of vitamin B-12 status in elderly people with moderately poor vitamin B-12 status. The Journal of nutrition. 2013;143(2):142-147.
55. Carmel R. Efficacy and safety of fortification and supplementation with vitamin B12: biochemical and physiological effects. Food and nutrition bulletin. 2008;29(2 Suppl):S177-187.
56. 2000. SCoFSCoFNEoO. Opinion of the Scientific Committee on Food on the tolerable upper intake level of vitamin B12. 2000.
57. McDougall J. Vitamin B12 Deficiency—the Meat-eaters’ Last Stand. McDougall Newsletter. November 2007.

How to prevent cancer

Vegetables and FruitsSix years ago the World Cancer Research Fund and the American Institute of Cancer Research published the mother of all literature reviews on food, nutrition, physical activity and the prevention of cancer (1).

A panel of 21 world-renowned scientists reviewed the research evidence and drew conclusions based on in-depth analysis of over 7,000 scientific studies published on cancer prevention over the last 50 years.

As a result of this review they made a number of recommendations:

  1. Be as lean as possible without becoming underweight
  2. Be physically active for at least 30 minutes per day
  3. Limit consumption of energy-dense foods and avoid sugary drinks
  4. Eat more of a variety of vegetables, fruit, whole grains and pulses
  5. Limit consumption of red meats and avoid processed meats
  6. If consumed at all, limit alcoholic drinks to 2 per day for men and 1 per day for women
  7. Limit consumption of salty foods and foods processed with salt
  8. Don’t use supplements to protect against cancer
  9. Do not smoke or chew tobacco
  10. Breastfeed exclusively for up to 6 months and then add other liquids and foods
  11. After treatment, cancer survivors should follow the recommendations for cancer prevention.

Since then further research has been conducted to see whether compliance with these recommendations has any effect on the risk of death from cancer and other diseases.

The findings were published in the American Journal of Clinical Nutrition on 3 April 2013 (2).

Researchers investigated nearly 380,000 people in nine European countries over 12 years and examined their diet and lifestyle to see how closely they complied with seven of World Cancer Research Fund/American Institute for Cancer Research’s (WCRF/AICR) Recommendations for Cancer Prevention.

They found that the risk of dying from several diseases, including cancer, circulatory diseases and respiratory diseases, can be reduced by 34 per cent if these recommendations are followed.

Those who most closely followed the WCRF/AICR Recommendations had a 50 per cent reduced chance of dying from respiratory disease, 44 per cent for circulatory disease and 20 per cent for cancer, when compared to the group with the lowest level of compliance.

The Recommendations with the greatest impact on reducing the risk of death from disease were being as lean as possible without becoming underweight (22 per cent reduced risk) and eating mostly plant foods (21 per cent).

In terms of cancer, limiting alcohol consumption and following the plant food recommendation reduced the risk of dying from the disease by the greatest margin, at 21 per cent and 17 per cent respectively.

The study is the first to examine breastfeeding as part of a combination of lifestyle changes to see what effect it has on risk of dying.  It showed that women who breastfed for at least six months had a reduced risk of death from cancer (ten per cent) and circulatory disease (17 per cent).

Although the WRCF/AICR recommendations were focused on the prevention of cancer, this study shows that adherence to these recommendations also reduces the risk of other diseases.

The bottom line is that maintaining a lean body by consuming a predominantly plant-based diet, being physically active and minimising intake of alcohol is most likely to protect you from cancer.  Looking after yourself in this way will also help to reduce your risk of circulatory and respiratory diseases.

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1. World Cancer Research Fund/American Institute for Cancer Research. Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective. Washington DC : AICR, 2007.

2. Adherence to the World Cancer Research Fund/American Institute for Cancer Research guidelines and risk of death in Europe: results from the European Prospective Investigation into Nutrition and Cancer cohort study. Anne-Claire Vergnaud et al. 3 April 2013, American Journal of Clinical Nutrition.

Pope Francis, food and the mystics

pope francisAlmost every article I have read about the new Pope Francis mentions his humility, the simplicity of his home, his dedication to serving the poor and the fact that he cooks for himself.

This led me to wonder what he eats.

According to an article in the Argentinian newspaper La Nacion in 2009, he chooses healthy frugal food and occasionally drinks a glass of wine. He is said to like fruit, skinless chicken and salads. When in Buenos Aires, he apparently never ate out in restaurants. He would eat by himself and would not even join meals at parish churches in his diocese. On the rarest of occasions, he might break from his routine of eating in his own quarters to visit a nunnery to enjoy bagna cauda – a fondue of anchovies, garlic and olive oil.

The simplicity of Pope Francis’ diet reminds me of the story of Daniel and his friends in the Christian Bible (Daniel 1).

King Nebuchadnezzar of Babylonia attacked Jerusalem and surrounded the city. He captured King Jehoiakim and seized treasures from the Temple.

a Daniel_befrore_NebuchadnezzarNebuchadnezzar then ordered his chief official, Ashpenaz, to select some young men from the noble and royal families of the Israelite exiles to serve in his court. They had to be handsome, intelligent, well-trained, quick to learn, and free from physical defects. Ashpenaz was to teach them to read and write the Babylonian language. The king also gave orders that every day they were to be given the same food and wine as the members of the royal court. After three years of this training they were to appear before the king. Among those chosen were Daniel, Hananiah, Mishael, and Azariah, all of whom were from the tribe of Judah. The chief official gave them new names: Belteshazzar, Shadrach, Meshach, and Abednego.

Daniel made up his mind not to let himself become ritually unclean by eating the food and drinking the wine of the royal court, so he asked Ashpenaz to help him. Ashpenaz was sympathetic to Daniel but was afraid of the king. So he said to Daniel, “The king has decided what you are to eat and drink, and if you don’t look as fit as the other young men, he may kill me.”

So Daniel went to the guard whom Ashpenaz had placed in charge of him and his three friends. “Test us for ten days,” he said. “Give us vegetables to eat and water to drink. Then compare us with the young men who are eating the food of the royal court, and base your decision on how we look.”

He agreed to let them try it for ten days. When the time was up, they looked healthier and stronger than all those who had been eating the royal food. So from then on the guard let them continue to eat vegetables instead of what the king provided.

God gave the four young men knowledge and skill in literature and philosophy. In addition, he gave Daniel skill in interpreting visions and dreams.

At the end of the three years set by the king, Ashpenaz took all the young men to Nebuchadnezzar. The king talked with them all, and Daniel, Hananiah, Mishael, and Azariah impressed him more than any of the others. So they became members of the king’s court. No matter what question the king asked or what problem he raised, these four knew ten times more than any fortune teller or magician in his whole kingdom. Daniel remained at the royal court until Cyrus, the emperor of Persia, conquered Babylonia.

Daniel was not alone in his experience with food. Mystics of all traditions teach that diet influences spiritual awareness.

plant based diets

Many spiritual masters of the East, including Hindus, and various schools of yoga, divide foods into three basic categories: Sattvic (pure), Rajasic (kingly), and Tamasic (impure). They teach that this last category of foods, which includes all flesh foods and eggs, is to be completely avoided. A sattvic diet consists of fresh, simple foods including: grains, beans, vegetables, fruits, seeds, nuts, and dairy. Sattvic foods are said to promote mental clarity, relaxation, meditation, and spiritual experience including inner visions. A rajasic diet includes very rich, spicy food, and a tamasic diet includes meat and alcohol. These are said to stimulate passions, promote mental agitation, and have an adverse effect upon concentration in meditation.

Those who take up the practices concerning the lower centres in the body, do take meat … but those who are anxious to rise above body consciousness and go into the Beyond have of necessity to eschew all that. This is the Path I have put before you. Liberation or salvation is something which starts only when you rise above body consciousness. For that reason, vegetarianism is the first essential.

(Kirpal Singh, The Night is a Jungle, published by Sant Bani Ashram of New Hampshire).

Guru Kabir, a great Master from Northern India, loved by Sufis, Sikhs, Jains, and Hindus alike, said:

The man who eats meat is a demon in human form. Keep away from him – his company will ruin your meditation.

(Kabir: the Weaver of God’s Name, Radha Soami Satsang Beas).

According to these teachers, the bad karma and other negative effects of flesh-eating apparently to some degree darkens one’s inner vision, interfering with the quality of one’s meditation, making it more difficult to reach the required deep levels of tranquility, clarity and concentration.

The concept of diet affecting spiritual awareness is not confined to Eastern mystics.

Many early Christians were vegetarian; also Clement of Alexandria, Origen, John Chrysostom, and Basil the Great. In some early church writings, Matthew, Peter and James (brother of Jesus and first leader of the Aramaic-speaking Jerusalem Church) were said to be vegetarian. According to the historian Eusebius, the Apostle “Matthew partook of seeds, nuts and vegetables, without flesh.” Many monasteries in ancient times practised vegetarianism and continue to do so.

clement of alexandriaClement of Alexandria wrote,

It is far better to be happy than to have your bodies act as graveyards for animals.

Modern day Seventh Day Adventists, for example, advocate a vegetarian diet.

Most conventional world religions in the West condone flesh-eating, but many esoteric traditions which have practised various forms of mysticism, are consistent in their agreement about the need for contemplative mystics to abstain from the flesh. The list of Western vegetarian paths includes: the Pythagoreans, followers of the Hermetic philosophy of Egypt, the Sethians, Theraputae, Essenes, the original Jewish Christians called Ebionites, the Gnostic religions, Manichaeans, some Catholic monasteries, some monasteries associated with the Orthodox Church – including the great mystery school on Mount Athos in Greece – and the Sufi mystics of Islam.

It may be no coincidence that the predominantly plant-based diet of Daniel and spiritual masters of many traditions, is virtually identical to that advocated by modern science. A diet which is believed to enhance spiritual openness also protects against cancer, heart-disease, stroke, diabetes, dementia, arthritis and the general ravages of aging.

Pope Francis’s simple diet may not only have helped to deepen his spiritual practice but also given him the physical strength to take on this monumental role at the age of 76. May he prove to be as wise, knowledgeable and visionary as Daniel.

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Plant-based diet for treating heart disease

Coronary artery before and after plant-based diet (C. Esselstyn 2001)

Coronary artery before (left) and after (right) plant-based diet (Esselstyn CB Jr: Preventive Cardiology 2001;4: 171-177)

Few people realise that a plant-based diet not only prevents heart disease but can also reverse it. Choosing whole grains, fruits and vegetables and avoiding simple sugars, and saturated and trans fats, as in meat and dairy products, has been shown to result in regression of coronary atherosclerosis after 1 and 5 years in some studies (1) (2) and to continue for over 12 years in other studies (3).

In contrast, standard medical interventions for cardiac patients, such as coronary artery bypass, bypass grafts, atherectomy, angioplasty or stenting, treat only the symptoms, not the disease.  It is therefore not surprising that patients who receive these interventions alone often experience progressive disease, graft shutdown, restenosis, more procedures, progressive disability, and ultimately death from disease (4).

Caldwell Esselstyn MD persuaded 18 cardiac patients to continue with a plant-based diet for over 12 years. Adherent patients experienced no extension of clinical disease, no coronary events, and no interventions. This finding is all the more compelling when we consider that the original compliant 18 participants experienced 49 coronary events in the 8 years before the study (4).

Some patients believe that there is no need to change their diet if they have had heart surgery, stents inserted and/or are taking drugs like statins and aspirin.

A recently published international study (5) indicated that individuals (more than 31,000 men and women of an average age of 66 in this study) who chose whole grains, fruits, vegetables, nuts, and fish over meat, eggs and refined carbohydrates had a 35% reduction in cardiac death rates over 5 years. That’s a 35% reduction in addition to the decrease from surgery and optimal medical management. And these men and women were older, where you’d expect diet to be able to reverse less.

So it is never too late to make simple changes to your diet and lifestyle to improve your long-term health, whether you have medically-managed heart disease or not.

If you have heart disease, you can eat a wonderful variety of delicious, nutrient-dense foods:

  • All vegetables except avocado. Leafy green vegetables, root vegetables, vegetables that are red, green, purple, orange, and yellow – every colour of the rainbow
  • All legumes—beans, peas, and lentils of all varieties.
  • All whole grains and products, bread and pasta, that are made from them—as long as they do not contain added fats.
  • All fruits

You need to avoid:

  • Red meat, poultry and fish
  • Dairy products
  • Oils of all kinds (even olive oil)


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(1) Ornish, D. et al (1998). Intensive lifestyle changes for reversal of coronary heart disease. JAMA, Vol 280, No. 23, 2001-2007

(2) Ornish, D. et al (1990). Can lifestyle changes reverse coronary heart disease?  The Lancet, 21 July 1990, Vol 336, No. 8708, 129-133

(3) Esselstyn, C. (2001).  Resolving the coronary artery disease epidemic through plant-based nutrition.  Preventive Cardiology, 4, 171-177

(4) Esselstyn, C.  Updating a 12-Year Experience With Arrest and Reversal Therapy for Coronary Heart Disease (An Overdue Requiem for Palliative Cardiology).  Article on Caldwell Esselstyn’s website.

(5) Dehghan, M. et al. Relationship Between Healthy Diet and Risk of Cardiovascular Disease Among Patients on Drug Therapies for Secondary Prevention: A Prospective Cohort Study of 31 546 High-Risk Individuals From 40 Countries. Circulation, 4 December 2012, 126: 2705-2712

Towards a new paradigm for public health

Food-Vegetables-01In 1990, physician and health economist Christopher Murray at Harvard University and medical demographer Alan Lopez at the World Health Organisation embarked on the first ever attempt to measure the global burden of disease and developed the now-famous Disability Adjusted Life Year (DALY) metric that made it possible to combine estimates of mortality and morbidity burden around the world. DALY is the sum of years lived with disability [YLD] and years of life lost [YLL].

Since then, there have been estimates in 1999 to 2002 and 2004. But the latest iteration of the project, Global Burden of Disease 2010, has been on a different scale, involving nearly 500 researchers from more than 300 institutions in 50 countries. It is the largest ever systematic effort to describe the global distribution and causes of a wide array of major diseases, injuries, and health risk factors.

Twenty years ago, the project assessed the burden of 107 diseases and injuries and ten selected risk factors for the world and eight major regions over one calendar year. Now, thanks to advances in technology, the availability of data, and the participation of experts around the world, as well as the leadership of a core group of researchers, the scope has increased to 291 diseases and injuries in 21 regions, for 20 age groups, and an estimation of trends from 1990 to 2010. Global Burden of Disease 2010 also includes an assessment of 67 risk factors.

The results, published yesterday in seven articles in The Lancet, are set to shake up health priorities across the world.

In summary, the analysis shows that infectious diseases, maternal and child illness, and malnutrition now cause fewer deaths and less illness than they did twenty years ago. As a result, fewer children are dying every year, but more young and middle-aged adults are dying and suffering from disease and injury, as non-communicable diseases, such as cancer and heart disease, become the dominant causes of death and disability worldwide. Since 1970, men and women worldwide have gained slightly more than ten years of life expectancy overall, but they spend more years living with injury and illness.

There were 52.8 million deaths in 2010 compared with 46.5 million deaths in 1990. Of these, 12.9 million were from ischaemic heart disease and stroke, or one in four deaths worldwide, compared with one in five in 1990. Cancer claimed 8 million lives in 2010 compared with 5.8 million in 1990; trachea, bronchus and lung cancer accounted for 20% of these. Twice as many people died of diabetes in 2010 – 1.3. million – than in 1990, which is higher than deaths from tuberculosis or malaria (1.2 million each). Deaths from HIV/AIDS increased from 0.30 million in 1990 to 1.5 million in 2010, reaching a peak of 1.7 million in 2006. The fraction of global deaths due to injuries (5.1 million deaths) was marginally higher in 2010 (9.6%) compared with two decades earlier (8.8%). This was driven by a 46% rise in deaths worldwide due to road traffic accidents (1.3 million in 2010) and a rise in deaths from falls.

The contributions of risk factors to regional and global burden of diseases and injuries has shifted substantially between 1990 and 2010, from risk factors that mainly cause communicable diseases in children to risk factors that mainly cause non-communicable diseases in adults.

The proportion of overall disease burden attributable to childhood underweight – the leading risk factor worldwide in 1990 – had more than halved by 2010, making childhood underweight the eighth risk worldwide, behind six behavioural and physiological risks, and household air pollution from solid fuels. Other risks for child mortality, such as non-exclusive and discontinued breastfeeding, micronutrient deficiencies, and unimproved water and sanitation, have also fallen. However, child and maternal undernutrition risks collectively still account for almost 7% of disease burden in 2010, with unimproved water and sanitation accounting for almost 1%.

Of the non-communicable disease risks, high blood pressure, high body-mass index, high fasting plasma glucose, alcohol use, and dietary risks have increased in relative importance. This overall shift has arisen from a combination of the ageing population, substantial achievements in lowering mortality of children aged younger than 5 years, and changes in risk factor exposure.

These broad global patterns mask enormous regional variation in risks to health. In sub-Saharan Africa, risks such as childhood underweight, household air pollution from solid fuels, and suboptimal breastfeeding continue to cause a disproportionate amount of health burden, despite decreasing. The shift to risk factors for non-communicable disease was clear in east Asia, North Africa and Middle East, and Latin America.

For people aged 15 to 49 years, the leading risk factor worldwide was alcohol use, followed by tobacco smoking including second-hand smoke, high blood pressure, high body-mass index, diet low in fruits, drug use, and occupational risk factors for injuries. Risk factor rankings in this age group stayed broadly similar between 1990, and 2010, with the exception of iron deficiency, which dropped from the fourth leading risk factor in 1990, to ninth in 2010.

High blood pressure, tobacco smoking including second-hand smoke, alcohol use, and diet low in fruits were all in the top five risk factors for adults aged 50 to 69 years and adults older than 70 years, in both 1990, and 2010, accounting for a large proportion of disease burden in both age groups. Globally, high blood pressure accounted for more than 20% of all health loss in adults aged 70 years and older in 2010, and around 15% in those aged 50 to 69 years. Tobacco smoking including second-hand smoke accounted for more than 10% of global disease burden in each of these age groups in 2010.

Globally, the sum of years lived with disability and years of life lost (DALY), was influenced most by dietary risk factors and physical inactivity – together these were responsible for 10% of the global disease burden in 2010.

Of the individual dietary risk factors, the largest attributable burden in 2010 was associated with diets low in fruits (4.9 million deaths), followed by diets high in sodium (4.0 million deaths), low in nuts and seeds (2.5 million deaths), low in whole grains (1.7 million), low in vegetables (1.8 million deaths), and low in seafood omega-3 fatty acids (1.4 million deaths). Physical inactivity and low physical activity accounted for 3.2 million deaths.

This impressive analysis of global health issues by Christopher Murray and colleagues provides much reason for hope but also challenges the current medical paradigm and global healthcare system.

It shows clearly that the focus of global health authorities in recent decades on reducing infection and malnutrition has paid off – life expectancy has increased almost everywhere. This focus needs to continue to minimise incidence of diseases like tuberculosis, malaria and HIV/AIDs.

It also reveals, however, that the leading causes of death in the modern developed world are conditions which cannot be controlled by vaccinations, antibiotics, improved sanitation or insecticides. The data provide evidence that the risk factors for non-communicable diseases like heart disease, cancer and diabetes, are predominantly related to poor diet and lifestyle.

The large attributable burden for dietary risk factors such as diets low in fruits, vegetables, whole grains, nuts and seeds, and seafood omega-3 fatty acids might come as a surprise to some. The large burden is caused by both high exposure, e.g., low intake of fruits and vegetables in many regions – and large effect sizes.

Given the crucial role of dietary and lifestyle factors in determining long-term health, the answer to alleviating the suffering created by these chronic non-communicable diseases does not lie in the current medical model, with its preoccupation with drugs and surgery. Our doctors are trained to relieve symptoms not to address the underlying causes of chronic disease. Powerful commercial interests in the food, pharmaceutical and health sectors drown out the voices of those who can see that the solution is really very simple.

Widespread consumption of plant-based diets, rich in vegetables, fruit, whole grains, beans, nuts and seeds, together with not smoking and more physical activity, would transform people’s lives and radically reduce healthcare costs. It is not rocket science.

Dr Murray, I salute you and your colleagues for a first rate piece of work. May the truths you have exposed become part of mainstream understanding as quickly as possible and lead to a sea change in our approach to health and well-being.

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Murray et al (2012). Global Burden of Disease 2010. The Lancet, 13 December 2012.

Diet and your eye sight

Recently one of my clients was diagnosed with age-related macular degeneration and was advised by a health professional to take supplements of the carotenoids lutein and zeaxanthin to prevent progression of this condition. Given that these supplements are expensive, she wanted to know if her investment would pay off.

As discussed below, the bottom line is that, to date, there is little scientific evidence to support the use of antioxidant supplements either to prevent or delay the progression of age-related macular degeneration. Indeed, there is evidence that such supplements may be harmful.

In contrast, there is scientific evidence that consumption of a plant-based diet with a variety of whole grains, vegetables and fruit has many benefits with regard to preventing and treating diseases like macular degeneration, and does no harm.  Further research is required in this area.

The best way to protect the health of your eyes is to eat plenty of different coloured vegetables and fruit; for example, broccoli, cabbage, kale, collard greens, green peas, spinach, courgettes, red and yellow peppers, winter squash, kiwi fruit, blueberries, oranges and mango.

What is age-related macular degeneration?

Age-related macular degeneration is an eye condition affecting older people, and involves the loss of the person’s central field of vision. It occurs when the macular (or central) retina in the eye develops degenerative lesions. The retina is the light-detecting membrane at the back of the eye. The macula contains a particularly high density of light receptors, especially cones (the receptors that detect colour) and so the macula is particularly important for seeing fine detail and objects directly in front of us. It plays a vital role in helping people to read, write, drive and perform other detailed tasks. It also enables us to recognise faces and see colour.

According to the World Health Organisation (1), globally, age-related macular degeneration ranks third as a cause of blindness after cataract and glaucoma; it is the primary cause in industrialized countries. Several forms of age-related macular degeneration exist.

Carotenoid pigments in the eye – lutein, zeaxanthin and meso-zeaxanthin

Pigments known as carotenoids are found within the eye. There are over 600 known carotenoids in nature but in the human eye, just three of these pigments – lutein, zeaxanthin and meso-zeaxanthin – form a concentrated ‘yellow spot’ in the macula, known as the macular pigment. This pigment has two main functions: it acts as an antioxidant and it filters light.

As short wavelength (blue) light passes through the retina to the photoreceptors and pigmented epithelial cells, reactive oxygen species are generated. The conversion of the light energy into a nerve impulse by the photoreceptors generates free radicals – unstable molecules which damage a variety 
of tissues – resulting in many of the diseases and conditions associated with ageing. Antioxidants in the eye are able to quench these free radicals, thereby protecting the eye from oxidative damage. Lutein, zeaxanthin and particularly meso- zeaxanthin are very effective antioxidants.

The pigments lutein and zeaxanthin can be found naturally in a number of food sources (2). For example, lutein can be found in yellow peppers, mango, bilberries and green leafy vegetables such as kale, spinach, chard and broccoli. Zeaxanthin can be found in winter squash, orange sweet peppers, broccoli, corn, lettuce, spinach, tangerines, oranges and eggs.

Blue light, because of its relatively high photon energy, more readily damages the retina than yellow or red light, which is less energetic. The macular pigment acts as a filter, particularly to blue light, and therefore protects against this damaging effect.

Given that the development of age-related macular degeneration is likely to involve a complex interaction of cellular and vascular factors, which may be promoted by light damage, oxidative stress, and inflammation, it is biologically plausible that a number of dietary components may be protective.

Effect of diet on age-related macular degeneration

The results of several epidemiological studies and clinical trials in the peer-reviewed scientific literature suggest that diets high in antioxidant nutrients (vitamins C and E, carotenoids such as lutein and zeaxanthin, fruit and vegetables that contain these nutrients, and non-nutritive antioxidants) or zinc are associated with a decreased occurrence of early or late age-related macular degeneration (3) (4). A high dietary intake of fat was associated with a higher prevalence or incidence of early or late age-related macular degeneration in numerous studies (5), whereas higher intakes of fish or omega 3 fatty acids were associated with lower rates of age-related macular degeneration (5).

Despite nutritional advice being available, awareness of the link between diet and eye health is poor. A survey conducted by the Eyecare Trust (6) found that Britons are oblivious to the fact that unhealthy lifestyles and obesity can substantially increase the risk of macular degeneration and ultimately blindness.

Efficacy of nutrient supplements for age-related macular degeneration

Some clinicians argue that it is difficult to obtain adequate amounts of the protective nutrients required for the eyes from a ‘normal’ diet. They thus prescribe high doses of nutrient supplements. But are these nutritional supplements effective?

A recently published Cochrane Review (7) identified four large, high-quality randomised controlled trials which included 62,520 people. The trials were conducted in Australia, Finland and the USA and investigated the effects of vitamin E and beta-carotene supplementation. These trials provide evidence that taking vitamin E and beta-carotene supplements is unlikely to prevent the onset of age-related macular degeneration. There was no evidence for other antioxidant supplements and commonly marketed combinations.

Another Cochrane Review (8) investigated whether progression of age-related macular degeneration may be slowed down in people who take antioxidant supplements (carotenoids, vitamins C and E) or minerals (selenium and zinc). The authors identified 13 randomised controlled trials which included 6150 participants; five trials based in the USA, two in the UK, two trials in Austria, and one trial in each of a further four countries (Australia, China, Italy and Switzerland). The review of trials found that supplementation with antioxidants and zinc may be of modest benefit in people with age-related macular degeneration. This was seen mainly in one large trial that followed up participants for an average of six years. The other smaller trials with shorter follow-up do not provide evidence of any benefit. Large well-conducted trials in a range of populations and with different nutritional status are required.

Safety of antioxidant nutrient supplements

Although generally regarded as safe, there is evidence that antioxidant supplements may have harmful effects. A Cochrane Review in 2008 (9) demonstrated that antioxidant supplements seem to increase mortality in sufferers of cancer and cardiovascular disease. This review was updated in 2012 (10) and found no evidence to support antioxidant supplements for primary or secondary prevention. Beta-carotene and vitamin E seem to increase mortality, and so may higher doses of vitamin A. The authors concluded that current evidence does not support the use of antioxidant supplements in the general population or in patients with various diseases in a stable phase, including gastrointestinal, cardiovascular, neurological, ocular, dermatological, rheumatoid, renal, endocrinological, or unspecified diseases.


The bottom line from all of this work is that, to date, there is little evidence to support the use of antioxidant supplements either to prevent or delay the progression of macular degeneration. Indeed, there is evidence that such supplements may be harmful.

In contrast, consumption of a plant-based diet with a variety of whole grains, vegetables and fruit has many benefits with regard to preventing and treating disease, and none of the disadvantages associated with nutritional supplements.  Further research and analysis of the literature is required in this area.

Further information and help

If you are suffering from a specific health problem or would just like to improve your general health and well-being, you will benefit from a personal nutrition consultation. Simple changes to diet and lifestyle can lead to significant improvements in the way you feel.  For a delicious recipe full of the carotenoids lutein and zeaxanthin, please click here.












How to lose weight

Many people resolve to go on a diet and adopt a healthier lifestyle, only to give up a few weeks later. Good intentions are often hard to put into practice and sustain. Here are a few suggestions to help you move towards and maintain a healthier weight:

1. Be realistic

Many people set themselves goals they find hard to achieve, such as fitting into a size 8 dress or a dinner jacket from 25 years ago. It is far better to begin by aiming to reduce your weight by 5 to 10 percent of your current weight. This may not turn you into a glamour model in a hurry, but it can lead to important improvements in weight-related conditions such as high blood pressure and diabetes. Once you have achieved this goal, you can always continue and aim to lose another 5 to 10 per cent until you are happy with your weight. Breaking the target down into manageable stages increases your chance of success.

2. Be gentle on yourself

Crash diets may work in the short-term but typically people regain all the weight they have lost and even add some more. Crash diets can also be dangerous. Not only this, but it is usually miserable being on a diet. Depriving yourself of food and feeling hungry sets up cravings which can lead to binge-eating followed by feelings of guilt. Neither deprivation nor hunger are necessary to lose weight if you are willing to take time and do the right things. If you cut out just 100 calories per day, the equivalent of a single can of fizzy drink or a bedtime snack, you could lose about 10 lb (4.5 kg) in a year. If you also added a brisk walk for half an hour a day five days per week, the weight loss could increase to 20 lb (9 Kg) in a year.

3. Keep moving

Next to not smoking, regular physical activity is arguably the best thing you can do for your health. It lowers the risk of heart disease, diabetes, stroke, high blood pressure, osteoporosis, and certain cancers, and can help to control stress and boost mood. Contrary to popular belief, the evidence for a simple relationship between physical activity and weight loss is equivocal, with some studies showing that exercise helps and others suggesting that it does not, possibly due to complex interactions between physical activity, diet and genes. If moderate to vigorous over an extended period, physical activity can help to maintain a healthy weight, provided you do not compensate by eating more as a self-reward. You would have to walk for 98 minutes to burn off the calories in one Mars Bar or swim for 45 minutes to burn off one slice of a pepperoni pizza, for example. For general health, any amount of exercise is better than none. The more you do, though, the better. This does not have to mean joining a gym or jogging. Many activities count as exercise: dancing, skating, gardening, cycling, scrubbing floors, washing the car by hand, or playing with children. Incorporate activity into your day by taking the stairs rather than the escalator, getting off the bus one stop before your destination and walking the rest, cycling to do errands rather than taking the car, and cutting back on watching television, playing computer games and other sedentary activities. Start slowly and gradually build up to more vigorous activity when your fitness increases.

4. Keep track

Many of us eat without thinking and have no idea how much we have consumed. Such lack of awareness can result in us eating and drinking more than we plan to. Try keeping a daily food diary for a while. List everything that you eat or drink, no matter how insignificant it seems. The calories can really add up, even just with drinks – one can of Coca Cola contains 142 calories, for example.

5. Eat food as nature intended

Research shows that people who eat at fast-food restaurants more than twice a week are more likely to gain weight and show early signs of diabetes than those who only occasionally eat fast food.

Our bodies were designed to consume food in the form that nature provides, with nothing added and nothing taken away.

Vegetables, fruit, nuts, seeds and whole grains all contain protein, carbohydrates, essential fats, vitamins, minerals and fibre. Fibre makes the food bulkier and less nutrient dense than highly processed food. This means that you have to eat a greater quantity of unprocessed food, like vegetables, to obtain the same amount of calories as highly processed foods, such as ice cream.

In the stomach and the gut, there are stretch receptors and nutrient receptors which signal to the body that it has enough food and to stop eating. If you eat highly processed foods, which are rich in calories but poor in vitamins, minerals and essential fats, such as white sugar and white bread, your body’s mechanism for signaling that it is full does not work properly – the gut is neither fully stretched nor receives the nutrients the body needs – so you carry on eating. This increases the chance of you consuming too many calories and becoming overweight, whilst not obtaining enough vitamins, minerals and essential fats.

The more unprocessed foods, like whole grains, vegetables, nuts and seeds, you include in your diet, the easier it is for your body to obtain the nutrients it needs without over-eating. Even if all you do is have porridge for breakfast instead of eating a sugary cereal or drinking strong coffee, you will find it easier to lose weight.

6. Keep your blood sugar stable

Another advantage of a food like porridge is that it has a gentle effect on blood sugar, or what’s called a low glycaemic index. When you eat porridge, glucose is released slowly and steadily into the bloodstream which helps to maintain energy levels over a longer period of time. This reduces hunger and cravings, so you tend to eat less. Other examples include whole grains such as brown rice (especially basmati), quinoa and whole-grain breads and pasta, as well as beans, nuts, fruits, and vegetables.

Eating foods that make your blood sugar and insulin levels shoot up and then crash may contribute to weight gain. Insulin tells the body to store surplus glucose as fat, so constantly excessive levels of glucose and insulin in the blood lead to weight gain. Such foods include white bread, white rice, and other highly processed grain products. So this is another good reason to increase the amount of unprocessed whole foods in your diet and reduce the amount of processed foods rich in calories.

7. Do not be afraid of good fats

Fat in a meal or in snacks such as nuts gives the food taste and helps you to feel full. Good fats, such as olive oil, have many benefits for health, including helping to improve your cholesterol levels when you eat them in place of saturated or trans fats or highly processed carbohydrates, like sugar and white flour products.

8. Drink water rather than fizzy drinks

Drinking juice or cans of sugary drinks can give you several hundred calories a day without even realising it. Several studies show that children and adults who consume sugar-sweetened beverages are more likely to gain weight than those who don’t, and that switching from these to water can reduce weight.

Using artificial sweeteners in soft drinks instead of sugar or high-fructose corn syrup seems like it would sidestep any problems with weight or diabetes. Artificial sweeteners deliver zero carbohydrates, fat, and protein, so they can’t directly influence calorie intake or blood sugar. Over the short term, switching from sugar-sweetened soft drinks to diet drinks cuts calories and leads to weight loss. Long-term use, though, may be a different story.

Some long-term studies show that regular consumption of artificially sweetened beverages reduces the intake of calories and promotes weight loss or maintenance. Others show no effect, while some show weight gain.

One concern about artificial sweeteners is that they uncouple sweetness and energy. Until recently, sweet taste meant sugar, and thus energy. Glucose is critical for the human brain to function, so the body has delicate feedback mechanisms involving the brain, stomach, nerves and hormones, to ensure that there is always a steady supply. When we eat something sweet, the human brain responds with signals – first with signals to eat more, and then with signals to slow down and stop eating. By providing a sweet taste without any calories, artificial sweeteners could confuse these intricate feedback loops. This could potentially throw off the body’s ability accurately to gauge how many calories are being taken in. Studies in rats support this idea. Researchers at Purdue University have shown that rats eating food sweetened with saccharin took in more calories and gained more weight than rats fed sugar-sweetened food. In addition, a long-term study of nearly 3,700 residents of San Antonio, Texas, showed that those who averaged three or more artificially sweetened beverages a day were more likely to have gained weight over an eight-year period than those who didn’t drink artificially sweetened beverages. At present, research findings are mixed, but there is a possibility that diet drinks may lead to weight gain in the longer term.

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Clinical guidelines on the identification, evaluation, and treatment of overweight and obesity in adults: the evidence report. National Institutes of Health, National Heart, Lung, and Blood Institute, Obesity Education Initiative

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Pereira MA, Kartashov AI, Ebbeling CB, et al. Fast–food habits, weight gain, and insulin resistance (the CARDIA study): 15-year prospective analysis. Lancet. 2005; 365:36–42

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Frank GK, Oberndorfer TA, Simmons AN, et al. Sucrose activates human taste pathways differently from artificial sweetener. Neuroimage. 2008; 39:1559-1569

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