The microbiome refers to all the viruses, parasites and bacteria living in and on the human body. It includes 37 trillion microscopic organisms, weighing three pounds. There is a microbiome on your skin, in your mouth, in your nose and sinuses, in your vagina if you\u2019re a woman, and in your gastrointestinal system. The microbiome is one of the body\u2019s five defense systems Dr. William Li talks about in his book \u201cEat to Beat Disease, The New Science of How Your Body Can Heal Itself.\u201d This column is specifically about the gut microbiome, which starts in the fetus when health-promoting bacteria are transferred from the mother via the placenta, and continues in the newborn when bacteria are transmitted in breast milk.<\/p>\n
In medicine we used to consider bacteria only as disease-causing agents. Now we know that \u2014 as Dr. Li puts it \u2014 \u201cthe majority of bacteria within our body work in highly sophisticated ways to defend our health and even influence our behavior.\u201d Here are some examples of what various gut bacteria can do:<\/p>\n
\u2022 produce brain neurotransmitters that influence our mood<\/p>\n
\u2022 release metabolites that can protect against diabetes<\/p>\n
\u2022 control the amount of abdominal fat we have<\/p>\n
\u2022 reduce stress and anxiety<\/p>\n
\u2022 influence the growth of new blood vessels, stem cells and immunity<\/p>\n
\u2022 reduce or increase harmful inflammation<\/p>\n
\u2022 lower cholesterol and protect against atherosclerotic plaque in the arteries<\/p>\n
\u2022 produce leptin, which suppresses hunger<\/p>\n
\u2022 produce substances the suppress the development of breast cancer<\/p>\n
\u2022 influence how patients respond to cancer immunotherapy<\/p>\n
A healthy gut microbiome is a diverse microbiome \u2014 with several species of bacteria. Disturbance of the microbiome, called dysbiosis, is linked to several diseases: Alzheimer\u2019s, atherosclerosis, autism, bipolar disorder, breast cancer, celiac disease, chronic fatigue syndrome, colorectal cancer, depression, diabetes, esophageal cancer, food allergies, gallbladder cancer, heart failure, IBS, leaky gut, liver disease, metabolic syndrome (pre-diabetes), multiple sclerosis, obesity, pancreatic cancer, Parkinson\u2019s disease, psoriasis, rheumatoid arthritis, schizophrenia, stomach cancer and ulcerative colitis.<\/p>\n
How do we encourage a health-promoting gut microbiome? The bacteria in our gut thrive on fiber. Dr. Li notes that \u201csince the dawn of Homo sapiens three hundred thousand years ago, fiber was the core of human sustenance,\u201d from ancient grains, nuts, legumes and fruits. The food eaten by primitive humans was also laden with bacteria. He goes on to say that \u201cthe modern dietary pattern of eating industrialized food has been around for only 0.02 percent of human existence.\u201d Most of the chronic diseases that make Americans sick and kill them \u2014 such as obesity, cardiovascular disease, diabetes and many forms of cancer \u2014 are related to the fact that we and the bacteria in our gut are being fed foods that are contrary to what we are genetically and historically meant to be eating.<\/p>\n
What foods contain fiber? Only plant foods \u2014 fruit, vegetables, whole grains, nuts and seeds. Animal products have none, and Dr. Li recommends avoiding them if you want to have a health-promoting microbiome.<\/p>\n
Antibiotics can cause dysbiosis for up to a year, so avoid them unless absolutely necessary. If you do take antibiotics, then fermented foods such as kimchi, sauerkraut and sourdough bread can give you needed probiotics, which can also be found as supplements. If you are on a plant-based diet and aren\u2019t taking antibiotics, you don\u2019t need probiotics.<\/p>\n
In summary, Dr. Li points out that \u201cwe should all make \u2026 better choices when we sit down to feed ourselves, because we are never eating for just one, or even two [in the case of a pregnant woman], but for 39 trillion. \u2026 Treat your bacteria well, and they will return the favor by defending your health.\u201d <\/p>\n
Greg Feinsinger, M.D. is a retired family physician who has a nonprofit: Prevention and Treatment of Disease Through Nutrition. He is available by appointment for free consultations (379-5718).<\/p>\n