Do high fat diets make us stupid and lazy?

babyeatingburgerinwombRats fed a high-fat diet show a stark reduction in their physical endurance and a decline in their cognitive ability after just nine days, a study by Oxford University researchers has shown.

The research, funded by the British Heart Foundation and published in the FASEB Journal, may have implications not only for those eating lots of high-fat foods, but also athletes looking for the optimal diet for training and patients with metabolic disorders.

‘We found that rats, when switched to a high-fat diet from their standard low-fat feed, showed a surprisingly quick reduction in their physical performance,’ says Dr Andrew Murray, who led the work at Oxford University and has now moved to the University of Cambridge. ‘After just nine days, they were only able to run 50 per cent as far on a treadmill as those that remained on the low-fat feed.’

High-fat diets, such as those that are prevalent in Western countries, are known to be harmful in the long term and can lead to problems such as obesity, diabetes and heart failure. They are also known to be associated with a decline in cognitive ability over long time spans. But little attention has been paid to the effect of high-fat diets in the short term.

Physical endurance – how long we can keep exercising – depends on how much oxygen can be supplied to our muscles and how efficiently our muscles release energy by burning up the fuel we get from the food we eat. In particular, using fat as a fuel is less efficient than using glucose from carbohydrates, but the metabolic changes induced by different diets are complex and it has been controversial whether high-fat feeding for a short time would increase or decrease physical performance.

The Oxford team set out to investigate whether rats fed a high-fat diet for just a few days showed any change in their physical and cognitive abilities.

All 42 rats were initially fed a standard feed with a low fat content of 7.5 per cent. Their physical endurance was measured by how long they could run on a treadmill and their short-term or ‘working’ memory was measured in a maze task. Half of the rats were then switched to a high-fat diet where 55 per cent of the calories came from fat. After four days of getting used to the new diet, the endurance and cognitive performance of the rats on the low- and high-fat diets was compared for another five days.

‘With the standard feed, 7.5 per cent of the calories come from fat. That’s a pretty low-fat diet, much like humans eating nothing but muesli,’ says Dr Murray. ‘The high-fat diet, in which 55 per cent of the calories came from fat, sounds high but it’s actually not extraordinarily high by human standards. A junk food diet would come close to that.

‘Some high-fat, low-carb diets for weight loss can even have fat contents as high as 60 per cent. However, it’s not clear how many direct conclusions can be drawn from our work for these diets, as the high-fat diet we used was not particularly low in carbs,’ he adds.

On the fifth day of the high-fat diet (the first day back on the treadmill), the rats were already running 30 per cent less far than those remaining on the low-fat diet. By the ninth day, the last of the experiment, they were running 50 per cent less far.

The rats on the high-fat diet were also making mistakes sooner in the maze task, suggesting that their cognitive abilities were also being affected by their diet. The number of correct decisions before making a mistake dropped from over six to an average of 5 to 5.5.

The researchers also investigated what metabolic changes the high-fat diet was inducing in the rats. They found increased levels of a specific protein called the ‘uncoupling protein’ in the muscle and heart cells of rats on the high-fat diet. This protein ‘uncouples’ the process of burning food stuffs for energy in the cells, reducing the efficiency of the heart and muscles. This could at least partly explain the reduction in treadmill running seen in the rats.

The rats that were fed a high fat diet and had to run on the treadmill also had a significantly bigger heart after nine days, suggesting the heart had to increase in size to pump more blood around the body and get more oxygen to the muscles.

While this research has been done in rats, the Oxford team and Andrew Murray’s new group in Cambridge are now carrying out similar studies in humans, looking at the effect of a short term high-fat diet on exercise and cognitive ability.

The results will be important not only in informing athletes of the best diets to help their training routine, but also in developing ideal diets for patients with metabolic disorders such as diabetes, insulin resistance or obesity. People with such conditions can have high levels of fat in the blood and show poor exercise tolerance, some cognitive decline, and can even develop dementia over time.

‘These are startling results,’ says Professor Kieran Clarke, head of the research team at Oxford University. ‘It shows that high-fat feeding even over short periods of time can markedly affect gene expression, metabolism and physical performance. By optimising diets appropriately we should be able to increase athletes’ endurance and help patients with metabolic abnormalities improve their ability to exercise and do more.’

‘In little more than a week, a change in diet appears to have made the rats’ hearts much less efficient,’ says Professor Jeremy Pearson, Associate Medical Director of the British Heart Foundation, who funded the research. ‘We look forward to the results of the equivalent studies in human volunteers, which should tell us more about the short-term effects of high-fat foods on our hearts. We already know that to protect our heart health in the long-term, we should cut down on foods high in saturated fat.’

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Journal reference:

Murray et al. Deterioration of physical performance and cognitive function in rats with short-term high-fat feeding. The FASEB Journal, 2009; DOI: 10.1096/fj.09-139691

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Oily fish may prevent dementia

57148013Experts estimate that over 24 million people worldwide suffer from dementia, and many of these people live in low- and middle-income countries. Recently, there has been growing interest in whether dietary factors, particularly oily fish and meat, might influence the onset and/or severity of dementia. Oily fish are rich in omega-3 long-chain polyunsaturated fatty acids, which some studies suggest are positively related to cognitive function in later life. 

Conversely, there is a suggestion from some studies that increased meat consumption may be related to cognitive decline. To examine this, a group of international researchers studied older people in 7 middle- to low-income countries. You can read the results of their study in the August 2009 issue of the American Journal of Clinical Nutrition

Data from 14,960 participants (≥65 y of age) living in China, India, Cuba, the Dominican Republic, Venezuela, Mexico, and Peru were analyzed. Dietary habits were assessed by using standard, culturally appropriate face-to-face interviews, and dementia was diagnosed by using validated culturally and educationally fair criteria. 

In each of the study countries, except India, there was an inverse association between fish consumption and dementia prevalence. These data extend to low- and middle-income countries previous conclusions from industrialized countries that increased fish consumption is associated with lower dementia prevalence in later life. 

The authors propose that this relation is not due to poor overall nutritional status in those with dementia, because meat consumption tended to be higher in this group. The relation between meat consumption and dementia remains unclear. 

To learn more about the effect of what we eat on the function of our brain, please come along to a Cooking for Health class on Food and Emotions, led by nutrition expert, Dr Jane Philpott

Preventing cancer through diet and physical activity

A new global policy report estimates that approximately 45 percent of colon cancer cases and 38 percent of breast cancer cases in the US are preventable through diet, physical activity and weight maintenance. The report also sets out recommendations for policies to reduce the global number of cancer cases.

 

policy_report_thumb1The overall message of the report, Policy and Action for Cancer Prevention, published yesterday by the World Cancer Research Fund (WCRF) and the American Institute for Cancer Research (AICR), is that all sections of society need to make public health, and cancer prevention in particular, a higher priority.

 

It includes estimates on the proportion of many different types of cancer that could be prevented through diet, physical activity and weight management. In the UK, akmost 40 per cent of the most common cancers could be prevented. That figure does not include smoking, which alone accounts for about a third of cancers.

 

Percentage of cancers that could be prevented via healthy diet, healthy weight and physical activity

 

US

UK

Brazil

China

Endometrium
(lining of the uterus)

70

56

52

34

Esophagus

69

75

60

44

Mouth, pharynx & larynx

63

67

63

44

Stomach

47

45

41

33

Colon

45

43

37

17

Pancreas

39

41

34

14

Breast

38

42

28

20

Lung

36

33

36

38

Kidney

24

19

13

8

Gallbladder

21

16

10

6

Liver

15

17

6

6

Prostate

11

20

n/a

n/a

These 12 cancers combined

34

39

30

27

 

Different Policy Recommendations For Different Groups

As part of the evidence-based report, thought to be the most comprehensive ever published on the subject, two independent teams of scientists systematically examined the evidence for how policy changes can influence the behaviours that affect cancer risk.  Following this, a panel of 23 world-renowned experts made a total of 48 recommendations, divided between nine different but often overlapping sectors of society – called “actor groups” in the report. These actor groups are: multinational bodies; civil society organizations; government; industry; media; schools; workplaces and institutions; health and other professionals; and people.

 

Among the recommendations:

  • Governments should require widespread walking and cycling routes to encourage physical activity.
  • Industry should give a higher priority for goods and services that encourage people to be active, particularly young people.
  • The food and drinks industry should make public health an explicit priority at all stages of production.
  • Schools should actively encourage physical activity and provide healthy food for children.
  • Schools, workplaces and institutions should not have unhealthy foods available in vending machines.
  • Health professionals should take a lead in giving the public information about public health, including cancer prevention.
  • People should use independent nutrition guides and food labels to make sure the food they buy for their family is healthy.

Professor Sir Michael Marmot, Chair of the WCRF/AICR Panel, said,

When people think of policy reports, they often think they only speak to governments. But the evidence shows that when it comes to cancer prevention, all groups in society have a vital role to play.

Panel member Tim Byers, MD, MPH of the University of Colorado Denver said,

Estimating cancer preventability is a very complex prospect that involves making a number of assumptions. Having said that, the figures in this report are as good an estimate it is possible to achieve about the proportion of cancer cases that could be prevented through healthy diet, regular physical activity and maintaining a healthy weight. On a global level every year, there are millions of cancer cases that could have been prevented. This is why we need to act now before the situation gets even worse.

The report also includes preventability estimates for the UK (which, like the US, is considered a high-income country), as well as for China and Brazil, which respectively represent low and middle-income countries.

 

Policy Report Represents the Next Step

The new WCRF/AICR Policy Report is a companion document to the expert report Food, Nutrition, Physical Activity and the Prevention of Cancer: A Global Perspective, which was published by AICR and WCRF in November of 2007. That expert report evaluated the scientific evidence from over 7000 studies and came away with 10 recommendations for lowering cancer risk.

The 2007 expert report identified the specific choices that people can make to protect themselves against cancer, but actually making those healthy choices remains difficult for many people,” said policy report panel member Shiriki Kumanyika, PhD, MPH, of the University of Pennsylvania School of Medicine. The policy report takes the next step – it identifies opportunities for us as a society to make those choices easier.

More information, including video interviews with panel members, Q and A documents, and other background materials, is available at: http://www.aicr.org/policy

Learn how to cook delicious food to boost your immune system and protect yourself and your family from cancer and other chronic diseases at Cooking for Health courses held throughout the year in Somerset, UK.

Fruit, vegetables and nuts may reduce onset of eye disease by 20 per cent

University of Liverpool scientists claim that the degeneration of sight, caused by a common eye disease, could be reduced by up to 20% by increasing the amount of fruit, vegetables and nuts in the diet. 

 

fruitsveggies

 

Age-related Macular Degeneration (AMD) is the leading cause of blindness in the UK, with 45% of those registered as blind suffering from the disease.  The condition results in a gradual loss of central vision, due to the failure of cells in the macular – the light sensitive membrane at the centre of the retina. There is currently no cure for the more common ‘dry’ form of the disease, which is suffered by 90% of AMD patients.  

 

Professor Ian Grierson, Head of Ophthalmology at the University, has produced a comprehensive cooking guide called ‘Fruit for Vision’, designed to add fruit and vegetables into everyday meals (published by Indigo Creative Marketing and the Macular Disease Society). The recipes will help AMD sufferers slow down the degeneration process by increasing micronutrient, vitamin and antioxidant intake in the diet. Non-sufferers can also use the book to add fruit, nuts and vegetables into each meal to protect against the disease. 

 

Layout 1

 

Professor Grierson said:

 

Poor eating habits have a huge impact on health in general and the health of your eyes is no exception. Eye problems such as AMD, cataract and even glaucoma can all be affected by what we eat. But a relatively minor change in diet – adding a little more fruit into our meals – can make a profound difference and can keep eye diseases like AMD at bay for up to 20% longer.   There are of course other risk factors related to AMD such as age, light exposure, smoking and being overweight. But if we can improve the kind of food that we eat, we could dramatically reduce the number of people who may suffer from eye diseases in the future.

To learn how to incorporate more fruit and vegetables in your diet and create imaginative and mouthwatering recipes for all the family, come along to a Cooking for Health class, held throughout the year in Somerset, UK. 

 

If you run a catering business, you can obtain valuable information and suggestions on how to increase fruit and vegetables in your menus at Healthier Catering courses, run by the nutrition expert, Jane Philpott, MA (Oxon), MSc, PhD.

 

 

Green and black tea may reduce stroke risk

Drinking at least three cups of green or black tea a day can significantly reduce the risk of stroke, a new University of California LA study has found. And the more you drink, the better your odds of staving off a stroke.

 

green-tea

 

The study results, published in the online edition of Stroke: Journal of the American Heart Association, were presented on 19 February at the American Heart Association’s annual International Stroke Conference in San Diego, California.

 

The UCLA researchers conducted an evidence-based review of all human observational studies on stroke and tea consumption found in the PubMed and Web of Science archives. They found nine studies describing 4,378 strokes among nearly 195,000 individuals, according to lead author Lenore Arab, a professor of medicine in the division of general internal medicine and health services research at the David Geffen School of Medicine at UCLA.

 

“What we saw was that there was a consistency of effect of appreciable magnitude,” said Arab, who is also a professor of biological chemistry. “By drinking three cups of tea a day, the risk of a stroke was reduced by 21 percent. It didn’t matter if it was green or black tea.”

 

And extrapolating from the data, the effect appears to be linear, Arab said. For instance, if one drinks three cups a day, the risk falls by 21 percent; follow that with another three cups and the risk drops another 21 percent.

 

This effect was found in tea made from the plant Camellia sinensis, not from herbal teas.

 

There are very few known ways to reduce the risk of stroke, Arab said. And developing medications for stroke victims is particularly challenging, given that the drug has to get to the stroke-damaged site quickly because damage occurs so fast. Arab said that by the time a stroke victim gets medical care, it’s nearly too late to impede the damage.

 

“That’s why these findings are so exciting,” she said. “If we can find a way to prevent the stroke, or prevent the damage, that is simple and not toxic, that would be a great advance.”

 

Though no one is certain which compounds in tea are responsible for this effect, researchers have speculated that the antioxidant epigallocatechin gallate (EGCG) or the amino acid theanine may be what helps. Antioxidants are believed to help prevent coronary artery disease.

 

“And we do know that theanine is nearly 100-percent absorbed,” Arab said. “It gets across the blood-brain barrier and it looks a lot like a molecule that’s very similar to glutamate, and glutamate release is associated with stroke.

 

“It could be that theanine and glutamate compete for the glutamate receptor in the brain,” she added.

 

Although a randomized clinical trial is needed to confirm this effect, the findings suggest that drinking three cups of green or black tea a day could help prevent an ischaemic stroke.

 

Whilst drinking a moderate amount of green and black tea clearly has benefits, excessive consumption can upset blood sugar regulation due to the relatively high caffeine content of the leaves of Camellia sinensis.  If blood sugar is not well-regulated in the body, it can lead to symptoms of fatigue, cravings for sugar and a heightened stress response.  If you like regular hot drinks throughout the day, why not try some herbal teas which also contain powerful antioxidants.  Many people enjoy drinking Rooibos (or redbush) tea, made famous by the heroine of The No. 1 Ladies Detective Agency, Precious Ramotswe (Alexander McCall-Smith).  Rooibos is naturally caffeine free and contains high levels of the antioxidants aspalathin and nothofagin.  Aspalathin also has anti-mutagenic properties.

 

rooibos_aspalathus_linearispict2814_

 

To learn more about green tea and herbal teas and their health benefits, why not come to a Cooking for Health course, held throughout the year in Somerset, UK.

 

 

 

References

A. Von Gadow, E. Joubert and C. F. Hansmann.  Comparison of the antioxidant activity of rooibos tea (Aspalathus linearis) with green, oolong and black tea Food Chemistry, Volume 60, Issue 1, September 1997, Pages 73-77

 

 

 

Salt in popular restaurant meals twice the amount a child should have in a day

New research published on 2 February 2009 by Consensus Action on Salt and Health (CASH) shows that many popular meals eaten in UK high-street restaurants can contain large amounts of salt, in some cases more than twice the daily maximum limit for an adult in a single meal.

CASH worked with Trading Standards officers around the country to measure the salt content of 96 popular menu items from 16 high street restaurant chains.  Samples were purchased from the restaurants and analysed for their salt content by the Public Analyst.

Nearly three quarters (72%) of the main course dishes contained 3g of salt or more, the maximum daily limit for a six year-old and half the adult daily limit, and seven of these contained 6g of salt or more, the maximum daily limit for an adult.  The saltiest dishes were not confined to one or two restaurants – six out of the sixteen (over one third, 38%) restaurants surveyed served a popular main course dish containing 6g of salt or more.

The saltiest main course surveyed was Old Orleans Chicken Fajitas, with 8.8g of salt per serving.  Old Orleans also serves Wings and Ribs with 7.6g of salt per portion.  A Pizza Express American Hot Pizza contains 7.5g of salt per portion and a Wagamama Ramen contains 7.2g of salt per serving.  By comparison, a popular main meal at Beefeater of Sirloin Steak, grilled tomato, flat mushroom and chips contains only 0.4g of salt.

American Hot Pizza

American Hot Pizza

Starters and side dishes were also surveyed, with Old Orleans Chicken Wings with spicy BBQ sauce and blue cheese dressing containing almost 5g of salt per portion. Strada Aglio Garlic Bread contains 3.3g of salt per portion, over half the adult recommended daily limit.

Restaurant

Dish

Salt per Portion (g)

Old Orleans

Chicken Fajitas

8.84

Old Orleans

Wings and Ribs (with fries)

7.59

Pizza Express

American Hot Classic Pizza

7.5

Wagamamas

Wagamama ramen

7.2

Zizzi

Pizza Sofia

6.7

ASK

Fiesta Di Carne Pizza

6.55

Frankie and Benny’s

Chicken Penne Romana

6.0

 

Professor Graham MacGregor, Professor of Cardiovascular Medicine at St George’s Hospital in London said:

“Keeping our salt consumption below the recommended maximum levels is vital.  If we are to reduce the numbers of people needlessly dying from heart attacks and strokes, then we all need to keep a check on our salt intake.  The food industry in this country is leading the world in reducing the amount of salt it adds to the foods we buy in shops and supermarkets, and labelling those foods clearly so that we can make informed decisions about the products we buy.  Unfortunately the same cannot be said for foods we eat in restaurants.  It simply beggars belief that almost five years after the Food Standards Agency launched its salt reduction programme, and with all the publicity there has been about the 6g a day target, some high street restaurants have done nothing to reduce the amount of salt they add to their meals.  If they had even considered this issue then we wouldn’t be finding meals containing more than a day’s salt limit in a single course.  By comparison, ready meals sold in supermarkets have had their salt content reduced considerably over the last few years, and when we last surveyed them, we found only a very few with salt contents over 3g salt per serving.”

Raymond Blanc, Chef Patron of the Manoir Au Quat’ Saisons said,

“I believe that good food does not need more than the very lightest of seasoning – there is no reason for good chefs to mask the flavour of their ingredients by adding too much salt. Remember herby, sour, bitter and acid are also wonderful catalysts of flavour.”

For information about a two-day course in Somerset, UK, tailored to equip caterers, and those involved in encouraging healthier catering practices, with information and practical tools to achieve healthier eating in the population, please click here.