How the food you eat affects your gut – Shilpa Ravella
Trillions of bacteria, viruses, and fungilive on or inside of us,and maintaining a good, balanced relationship with themis to our advantage. Together, they form the gut microbiome,a rich ecosystem that performs a varietyof functions in our bodies. The bacteria in our gutscan break down food the body can’t digest,produce important nutrients,regulate the immune system,and protect against harmful germs. We don’t yet have the blueprintfor exactly which good bacteria a robust gut needs,but we do know that it’s importantfor a healthy microbiometo have a variety of bacterial species. Many factors affect our microbiomes,including our environment,medications like antibiotics,and even whether we were deliveredby C-section or not. Diet, too, is emerging as one of the leading influenceson the health of our guts. And while we can’t control all these factors,we can manipulate the balanceof our microbesby paying attention to what we eat. Dietary fiber from foods like fruits, vegetables, nuts, legumes, and whole grainsis the best fuel for gut bacteria. When bacteria digest fiber,they produce short chain fatty acidsthat nourish the gut barrier,improve immune function,and can help prevent inflammation,which reduces the risk of cancer. And the more fiber you ingest,the more fiber-digesting bacteriacolonize your gut. In a recent study, scientists exchangedthe regular high-fiber dietsof a group of rural South Africanswith the high-fat, meat-heavy dietsof a group of African-Americans. After just two weeks on the high-fat,low-fiber, Western-style diet,the rural African group showedincreased inflammation of the colon,as well as a decrease of butyrate. That’s a short chain fatty acid thoughtto lower risk of colon cancer. Meanwhile, the group that switchedto a high-fiber, low-fat diethad the opposite result. So what goes wrong with our gut bacteria when we eat low-fiber processed foods?Lower fiber means less fuelfor the gut bacteria,essentially starving them until they die off. This results in less diversityand hungry bacteria. In fact, some can even start to feedon the mucus lining. We also know that specific foods can affect gut bacteria. In one recent microbiome study,scientists found that fruits,vegetables,tea,coffee,red wine,and dark chocolatewere correlated with increased bacterial diversity. These foods contain polyphenols,which are naturally occurring antioxidant compounds. On the other hand,foods high in dairy fat,like whole milk, and sugar-sweetened sodaswere correlated with decreased diversity. How food is prepared also matters. Minimally processed, fresh foodsgenerally have more fiberand provide better fuel. So lightly steamed,sautéed,or raw vegetablesare typically more beneficialthan fried dishes. There are also ways of preparing foodthat can actually introduce good bacteria,also known as probiotics,into your gut. Fermented foods are teemingwith helpful probiotic bacteria,like lactobacillusand bifidobacteria. Originally used as a way of preserving foodsbefore the invention of refrigeration,fermentation remains a traditionalpractice all over the world. Foods like kimchi,sauerkraut,tempeh,and kombuchaprovide variety and vitalityto our diets. Yogurt is another fermented food that canintroduce helpful bacteria into our guts. That doesn’t necessarily mean thatall yogurt is good for us, though. Brands with too much sugarand not enough bacteriamay not actually help. These are just general guidelines. More research is needed before we fully understandexactly how any of these foodsinteract with our microbiomes. We see positive correlations,but the insides of our guts are difficultplaces to make direct observations. For instance, we don’t currently knowwhether these foods are directlyresponsible for the changes in diversity,or if something more complicatedis happening. While we’re only beginning to explorethe vast wilderness inside our guts,we already have a glimpse of how crucialour microbiomes are for digestive health. The great news is we have the powerto fire up the bacteria in our bellies. Fill up on fibers,fresh and fermented foods,and you can trust your gutto keep you going strong.