The most exciting field of study in nutrition over the past ten years concerns the microbiome, vast populations of microorganisms living inside and on the outside of our bodies. Researchers are beginning to understand the extent to which our health depends upon the health of microbes dwelling in and upon us and that the types of foods we ingest have profound effects upon the health of these microorganisms. Foods that stimulate beneficial bacteria to flourish in the gastrointestinal system strengthen the immune system, improve mental function, reduce chronic inflammatory diseases, help reduce body fat, and have many other healthful effects. Conversely, foods that damage tissue of the gastrointestinal tract, raise blood sugar levels, or stimulate detrimental bacteria to proliferate, weaken the immune system, increase risks for chronic inflammatory diseases, and cause excessive body fat accumulation.
A brief review of the effects of foods upon two common types of bacteria in our microbial armies illustrates why the standard american diet, high in processed foods—especially grain-based foodstuffs—causes us to become obese. Bacteriodetes and Firmicutes constitute 90% of the bacteria populating the human gut. Acting on foods we eat, Firmicutes extract many more calories per gram than do Bacteriodetes. Scientists compare ratios of bacteria in different groups of people with markedly different diets by analyzing the composition of their feces. People with microbiomes dominated by Firmicutes have much higher rates of obesity and diabetes than those with GI tracts dominated by Bacteriodetes.
How do we apply this research to our everyday lives?
Simple: feed our troops well; eat foods that nourish beneficial microbes in our gut; avoid foods that damage our GI tract, allow harmful microbes to proliferate, or cause us to store excessive body fat. In short, become internal environmentalists. It would be hypocritical to pledge collectively, as international citizens, to take care of our external environment—to stop polluting skies, oceans, and forests—but, simultaneously, to continue pouring toxic foods down our throats, foods that contaminate our internal environments, especially our microbiomes.
To feed our microbial troops well, we should first of all become Vegetabletarians, eaters of abundant amounts of vegetables. Whether we eat animal products or not, at every meal we should eat vegetables in some form. Most vegetables have a low glycemic index and, therefore, do not cause an insulin reaction, the hormonal trigger for storing body fat. A salad of raw vegetables, especially scallions, garlic, and dandelion greens, supplies our microbial troops with prebiotics, the type of fiber that our beneficial microbial defenders love to digest. Fermented vegetables, such as sauerkraut or kimchi, are probiotics, that is, contain large amounts of the microbes themselves. By eating fermented vegetables, we are sending in reinforcement troops to keep our armies strong. Steamed or sautéed vegetables or soups contain some nutrients that are more easily digested and assimilated than raw vegetables. Vegetables make our microbiomes happy and make us healthy. To protect our microbial soldiers, we must avoid foods that damage the cells of the GI tract, that raise blood sugar levels, that we cannot digest completely, or that allow pathogenic bacteria to proliferate. Lunchmeat and fast-food burgers might come to mind first. However, grain-based foodstuffs are the most important irritants to our microbiomes. More than 50% of the calories consumed in the U.S. are from grains, the seeds of grass. We cannot eat grass seeds at all unless they are highly processed—bread, bagels, crackers, etc. All grains have high glycemic indexes, raise blood sugar levels, trigger insulin secretion and fat storage, damage the cell walls of the small intestine, and inflame our nervous and cardiovascular systems. We can burn them for energy in our bodies, but they leave severely toxic residual cellular debris, called advanced glycation end products (AGEs)— similar to creosote from a wood stove. Grains are the fossil fuels of the American diet.
To summarize what nutritional research now tells us: Eat Greens Not Grains. The best thing each of us can do to become leaner and healthier is to gradually replace grain-based foodstuffs in our diets with raw, fermented, and cooked greens. The American Diet Revolution has begun