Research fellow at the Canadian Research and Development Centre for Probiotics, Lawson Health Research Institute, London, Ontario, Canada
2008年8月18日 | EN
Jonathan Wells is right to suggest that commercial interests drive rising obesity (see Obesity researchers must understand how capitalism works). The reach of highly profitable global companies has led to the 'Westernisation' of African diets, substituting products high in sugar and fat for home-made foods with balanced nutritional values.
Now, many people in developing countries are glorifying fast foods, which contain lots of preservatives and trans-fats, and help deplete the gut microbiota that preserve health (particularly Bacteroidetes). All humanity would be dead without these gut microorganisms that outnumber human cells. Their role includes immune modulation through prevention of colonization by pathogenic microbes and metabolic functions. They break down dietary toxins, synthesize micronutrients, ferment indigestible food substances and aid absorption of minerals.
Fermented food traditions, which actually foster such microbiota, are less diligently practised and are no longer passed from generation to generation. Instead we have rising obesity.
Obesity results from altering the body's regulation of energy intake, expenditure and storage.
Bacterial lipopolysaccharides, derived from the intestinal microbiota, may help regulate the onset of obesity and diabetes with the lipopolysaccharides binding at the surface of innate immune cells.
Energy regulation by the gut microbiota occurs through a number of interrelated microbial mechanisms such as fermentation of indigestible dietary polysaccharides into absorbable forms, intestinal absorption of monosaccharides and short-chain fatty acids with their subsequent conversion to fat within the liver, and regulation of host genes that promote deposition of fat in lipocytes.
Exposure to a high-fat diet and diet-induced obesity can simultanously lead to chronic inflammatory reactions known as "high-fat diet-induced metabolic syndrome"
The composition of gut microbiota differs significantly between obese and lean humans. Scientific research suggests that the metabolic activities of the gut microbiota help people extract calories from food and store them as fat for later use.
It may soon be possible to treat obesity by manipulating patients' microbial ecology. In contrast to the commercialisation and production of obsegenic foods, the production of microbe foods or probiotics could bring improvements in health.
This benefit came to light in 1907, when Eli Metchnokoff hypothesised that diminishing the number of 'putrefactive' bacteria in the gut by replacing them with lactic acid bacteria could improve bowel health and prolong life.
In the past 30 years, significant advances have been made in selecting and characterising specific probiotic cultures, and substantiating their health benefits.
Comparative genomics has already identified key genetic features responsible for the beneficial properties ascribed to probiotic lactic acid bacteria. Developed countries have incorporated the concept into their clinical and nutritional milieu to reduce the impact of fast foods, but many developing countries have yet to follow suit.
Probiotics are most often incorporated in yogurt and fermented milk, but other food lines are now available, and numerous products are sold in tablet, capsule and powder forms in the West.
The United Nations and World Health Organisation have called for probiotic products to be made more widely available for relief work and to populations at high risk of illness and death. But this message has yet to be heeded by multinational companies producing and marketing fast foods in developing countries. Much more should and can be done to market products that may reduce the obsegenic impact of the spread of fast food.