A study from Stanford shows that eating fermented foods such as yogurt, kefir, fermented cottage cheese, kimchi, fermented vegetables, vegetable brine drinks, and kombucha increases the diversity of colon bacteria, which decreases inflammation associated with many different diseases (Cell, Jul 6, 2021;S0092-8674(21)00754-6). The more fermented foods you eat, the greater the gain in bacterial diversity. Low microbiome diversity is associated with increased risk for heart attacks, certain cancers, obesity and diabetes.
Your immune system is supposed to be good for you, helping to attack and kill germs and prevent them from multiplying in your body. However, if your immune system stays active all the time, it can use the same chemicals and cells to attack you to cause disease. To a large degree, your immune system is controlled by the bacteria in your colon. Healthful bacteria stay in your colon and do not try to invade your colon cells, while the harmful types of bacteria try to get into your colon cells, turning on your immune system to cause inflammation and increase your risk for many diseases.
You have more than a thousand different types of bacteria in your colon. The foods that you eat determine whether you grow healthful or harmful bacteria in your colon because colon bacteria eat the same foods that you do. Some foods, such as mammal meat, processed meats, sugar added foods, and fried foods, are known to foster growth of harmful bacteria in your colon. These inflammation-producing foods decrease the diversity of colon bacteria by reducing healthful bacteria and increasing harmful bacteria. Anything that increases bacterial diversity decreases inflammation and promotes health, while anything that increases inflammation is associated with increased risk for disease.
The Study on Fermented Foods
Researchers at Stanford followed 36 healthy adults for a 10-week diet that included either fermented foods or high-fiber foods. The researchers analyzed blood and stool samples collected during a three-week pre-trial period, the 10 weeks of diet, and a four-week period after the diet when the participants ate their usual diets. The results showed that after just three weeks, the fermented foods reduced inflammation by decreasing:
• activation of four types of immune cells, and
• blood levels of 19 inflammatory proteins, including interleukin 6 (IL6) that is linked to rheumatoid arthritis, type II diabetes, and chronic stress.
Other studies also show that fermented foods decease inflammation by changing colon bacteria (Microbiome, Feb 11, 2020;8(1):15). The high-fiber diet did not decrease any of the 19 inflammatory proteins and did not change gut microbial diversity in this short study period, but would be expected to do so over a longer period of time (Science, Aug 11, 2017:357(6351):548-549).
You already know that I recommend a high-fiber diet that includes plenty of fruits, vegetables, whole grains, beans, nuts and other seeds, and I have frequently suggested that you include fermented foods such as yogurt or kefir. Many other studies have found that fermented foods and soluble fiber are associated with reduced risk for weight gain, diabetes, certain cancers, and heart attacks. Increasing your intake of fermented foods can quickly improve your colon bacteria to help reduce inflammation and disease.