Dietary Fiber and Whole grains

Written by Dr Harold Gunatillake Health writer

When you think of a balanced nutritious diet for your health, gut microbial benefits, and longevity you need to give priority to foods that are conducive to good health, including dietary fibre. Next time you visit the grocery or super-market, purchase items and foods having high fibre and whole grains. This includes mainly green vegies, root veggies, fruits, unprocessed grains, excluding meat products. Avoid purchasing smoked foods prepared with meat, or fish as there is a correlation between the frequency of consumption of smoked foods and intestinal cancer.

There are many bio-active components in those ingredients, such as resistant starches in the grains, and green vegies, including vitamins, minerals, phytochemicals, antioxidants, and soluble fibre providing foods as prebiotics to the gut flora.

Such foods will prevent diabetes, obesity, and cardiovascular disease, cancer which includes mouth, throat, intestinal and breast, and other chronic non-communicable illnesses.

Dietary fibre is also a form of carbohydrate forming the skeleton of plants and when consumed are not digested by our gut enzymes and not absorbed in the small intestines. They have many fractions includes arabinoxylan, inulin, pectin, bran, cellulose, Beta-glucan and resistant starch, which plays an important role in our health.

Such fibrous components give bulk and viscosity to the digested food and help the intestinal muscles to move them towards the large gut. The fibrous components enter the large bowel and they get fermented by the gut bacteria to form short chain fatty acids. These fatty acids results in an increase in gut microbiota gene richness, and some of them increase the intestinal Bifidobacterium and lactic acid bacteria. They may have both metabolic and immune effects and further creates a healthy inner lining, decrease in inflammatory responses of the gut to prevent diseases like ulcerative colitis, Crohn’s disease and cancer, among others.

On the other hand people who eat less unprocessed grains and more proteinous foods like meat produce more harming microbes like acteroids, Alistipes, Bilophilia and Ruminococcus genera and reduce the good microbes like the Bifidobacterium and lactobacillus. This does not apply to plant proteins. The latter tends to increase Bifidobacterium and Lactobacillus, leading to an increase of short chain fatty acids (SCFAs)

Those harmful microbes mentioned produce trimethylamine-N-oxide (TMAO) a pro-atherogenic substrate that may increase the incidence of cardio-vascular disease.

New research from Finland suggests that higher blood levels of indolepropionic acid- a by-product of gut bacteria that is increased by a fibre-rich diet- helps to protect against type 2 diabetes. Also, diets rich in fibre and whole grain foods appear to increase levels of indole-propionic acid, which in turn raises the insulin production by the beta cells in the pancreas.
Knowing these biochemical mechanisms working in your gut, it is sensible to consume more vegetarian type of diets including high fibre grains.

WE are fortunate that green vegies, high fibre foods are within the reach of the average person in Sri Lanka, and meats are so expensive beyond the reach of average wage earners. Some of the high fibre vegies like cabbages, cauliflower, carrots, cucumber, leafy vegetables used for making ‘mallums’ are quite cheap in the markets, in Sri Lanka and abroad.

Unfortunately, Sri Lankans love white bread and white processed rice. They are more tasteful and easy to digest than the unprocessed and the latter is produced less and more expensive to the average person. White flour is bleached and it destroys the vitamin E. Extra refining of white flour pushes the price up. Indi-appams (string hoppers) cooked both with brown and white rice flour seems to be equally popular (personal observation). 20 string-hoppers cooked from brown flour cost only rupees hundred- less than an Australian dollar. That is how cheap the street foods could be.

Whole meal flour has its endosperm as in processed white flour, bran-which gives the brown colour, wheat germ and the whole kernel, and enriched with vitamins and minerals. They have insoluble cereal fibre which passively attracts water which helps to soften stool, increase the bulk and shorten pass over time through the intestine. The wheat germ in whole meal is rich in vitamin E and helps in reducing the blood cholesterol levels and hence reducing the risks of cardiovascular problems.

Coming back to dietary fibre, in addition to increasing faecal bulking and viscosity, there is less contact time between potential carcinogens and mucosal cells. Dietary fibre also increases the binding between bile acids and carcinogens. Also they increase the levels of antioxidants and increases the amount of oestrogen excrete in the faeces due to an inhibition of oestrogen absorption in the intestines (Ref: Effects of Dietary Fibre and its components on Metabolic Health- James M. Lattimer and Mark D. Haub)
Conclusions: Next visit to the super-market –think of purchasing whole meal foods with high dietary fibres and keep away from processed foods, for your good health, and longevity.