Colon cancer, gut microbes and your diet

A typical Western diet, rich in meat and fats and low in complex carbohydrates, is a recipe for colon cancer, Professor Stephen O’Keefe from the University of Pittsburgh, USA, told the Society for General Microbiology meeting at Harrogate today (Tuesday 31 March). He described an expanding body of evidence to show that the composition of the diet directly influences the diversity of the microbes in the gut, providing the link between diet, colonic disease and colon cancer.

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People eating a healthy diet containing high levels of complex carbohydrate (e.g., whole grains like wholewheat bread, brown rice, quinoa, millet, vegetables, fruit) had significant populations of micro-organisms in their gut called Firmicutes. These bacteria use the undigested residues of starch and proteins in the colon to manufacture short-chain fatty acids and vitamins such as folate and biotin that maintain colonic health. One of these fatty acids, butyrate, not only provides most of the energy to maintain a healthy gut wall, but it also regulates cell growth and differentiation. Both experimental and human studies support its role in reducing colon cancer risk.

However, gut microbes may also make toxic products from food residues. Diets high in meat will produce sulphur – this decreases the activity of ‘good’ bacteria that use methane and increases the production of hydrogen sulphide and other possible carcinogens by sulphur-reducing bacteria.

“Colon cancer is the second leading cause of cancer-related deaths in adults in Westernized communities.” said Professor O’Keefe, “Our results suggest that a diet that maintains the health of the colon wall is also one that maintains general body health and reduces heart disease”.

“A diet rich in fibre and resistant starch encourages the growth of good bacteria and increases production of short chain fatty acids which lessen the risk of cancer, while a high meat and fat diet reduces the numbers of these good bacteria.” Professor O’Keefe went on. “Our investigations to date have focused on a small number of bacterial species and have therefore revealed but the tip of the iceberg, our colons harbour over 800 bacterial species and 7,000 different strains. The characterization of their properties and metabolism can be expected to provide the key to colonic health and disease”

To learn more about which foods help to maintain the health of your gut and how to cook delicious recipes using them, please come along to a Cooking for Health course, held throughout the year in Somerset, UK.

Alzheimer’s Disease, metabolic disorders and the role of diet

Accumulating evidence for the role of metabolic disorders such as insulin resistance, diabetes, obesity and hypertension in increasing the risk of Alzheimer’s disease and vascular dementia, is reviewed in a new paper published this month in the Archives of Neurology.

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In the same journal, compelling evidence is presented that higher pre-diagnosis total cholesterol, low-density lipoprotein cholesterol, and diabetes are associated with faster cognitive decline in patients with incident Alzheimer’s disease.

A cohort of 156 patients with incident Alzheimer’s Disease (mean age 83 years) were followed for up to 10 years.  Changes in a composite score of cognitive ability were monitored from diagnosis onwards.

“These findings indicate that controlling vascular conditions may be one way to delay the course of Alzheimer’s, which would be a major development in the treatment of this devastating disease as currently there are few treatments available to slow its progression,”

said Yaakov Stern, Ph.D., a professor at the Taub Institute for the Research on Alzheimer’s Disease and the Aging Brain and director of the Cognitive Neuroscience Division of the Gertrude H. Sergievsky Center at Columbia University Medical Center, and senior author of the paper.

“Preventing heart disease, stroke and diabetes – or making sure these conditions are well managed in patients diagnosed with them – can potentially slow the disease progression of Alzheimer’s,” said Dr. Stern.

Diets high in fruit, vegetables, fibre and unsaturated fats, and low in sugar, salt and saturated fat are known to reduce the risk of a range of chronic conditions, such as diabetes, heart disease and stroke.  This means eating more plant-based foods and less processed and animal-based foods.

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Stabilising blood sugar is crucial.  This may be done by eating a diet with a low glycaemic load, that is, one that includes moderate quantities of complex carbohydrates which release glucose slowly into the bloodstream.  Whole grains, such as whole-wheat bread, brown rice, quinoa, millet and buckwheat are valuable for helping to ensure smooth regulation of blood sugar.  In contrast, highly refined carbohydrates, such as white bread, white rice, white pasta and table sugar, create a roller-coaster of blood sugar highs and lows, which if left unchecked, can ultimately give rise to insulin resistance and eventually to diabetes.  Potatoes release sugar into the bloodstream almost as fast as table sugar and thus should be eaten sparingly, unless you are lean and exercise regularly.  Consuming protein with carbohydrates at every meal has also been found to help regulation of blood sugar.

Increasing the quantity of vegetables and fruit in the diet is also vital.  Blood sugar levels are easier to maintain if vegetables are emphasized more than fruit, as some fruit contains a lot of sugar.  A minimum of 5 portions of fruit and vegetables per day is recommended.  For easy tips for increasing the amount of fruit and vegetables in your diet please click here.

Unsaturated fats found in plant oils, such as olive oil and the oils of nuts and seeds, and in oily fish, are beneficial for preventing heart disease and other vascular health conditions.  For practical suggestions for ways to incorporate more healthy unsaturated fats in your diet please click here.

For information and practical tuition in how to put all these recommendations together to create fabulous food that protects you from diabetes, heart disease and Alzheimer’s Disease, please come to a Cooking for Health course, run by nutrition expert, Dr Jane Philpott.