This fermented cabbage Korean staple is rich in two classes of good bacteria associated with better gut health (they're called Lactobacillus and Bifidobacterium if you want to get technical). Early research suggests fermented kimchi alters the bacterial environment of the gut, potentially reducing the risk of insulin resistance, obesity, and blood pressure. Not a fan of kimchi? Try other fermented foods like sauerkraut, kombucha, or tempeh.

Like kimchi, yogurt is a naturally fermented food that can offer some serious probiotic power. Research found that women who ate a probiotic-rich yogurt for four weeks reported better gastrointestinal health, digestive comfort, and an overall improvement in quality of life.

While most yogurts contain bacteria, sometimes the strains used aren’t super beneficial or the heat-processing protocol kill off the good stuff. For that reason, you’ll want to look for a yogurt that has at least 1 billion live or active colony-forming units (CFUs) on the label. Sick of yogurt? Try kefir instead.

Also known as a sunchoke, the Jerusalem artichoke is a tasty tuber packed full of the prebiotic fiber inulin. Early research suggests that inulin from the sunchoke increases the good bacteria in the gut, suppresses the bad pathogenic bacteria, and helps promote regularity.

But a word to the wise—inulin in excess has been known to cause some serious gas. Hey, there’s a reason these babies are affectionately nicknamed “fart chokes.” We suggest introducing them to your diet slowly in small amounts until your gut adjusts. If you can’t find these nutty-sweet tubers, other great sources of inulin fiber include chicory root, asparagus, dandelion root, onions, and garlic.

In addition to providing inulin fiber, garlic is also rich in the natural prebiotic fructooligosaccharides (FOS). Early in vitro research has found that garlic increases the good Bifidobacteria in the gut, which may help prevent some gastrointestinal diseases and irregularity. If you want to double down on those FOS fibers, other rich sources include leeks, asparagus, and onions.

Unripe bananas are loaded with prebiotic fiber-resistant starch, which is broken down by gut bacteria to develop those SCFAs (like butyrate) we discussed. Findings from a meta-analysis and systematic review of randomized control trials suggest that supplementing the diet with resistant starch significantly improved bowel movements and the overall function of the gut.

Research suggests you’ll likely want to aim for at least 6 grams of resistant starch per meal to reap the most benefits. So in addition to eating green bananas, you’ll also want to up your root veggies, legumes, and grains. And not just any grains—believe it or not, cooling off your starch (a.k.a. eating leftover cooked rice right from the fridge) can significantly increase the resistant starch content.

Barley is loaded with the prebiotic fiber beta-glucan, which research has found can increase the growth and probiotic benefits of four different good Lactobacillus strains. A randomized control trial also found similar outcomes for the good Bifidobacteria when volunteers supplemented their diets with fiber-rich barley. Not a fan of the grain? Try whole oats to get the same effect.

We know that too much alcohol isn’t a good thing for our health overall, but it turns out it's really not good for our guts. Early research looking at alcoholics suggests that chronic alcohol intake is associated with changes in the bacterial microbiome, which may play a role in alcohol-induced tissue injury and liver disease. 

The health of non-nutritive sweeteners has been a hot topic of debate for years, but with increasing interest in gut health, we may see a clearer story emerge. Rat research dating back to the 1980s had linked the use of artificial sweeteners to shifts in the bacterial populations in the animal microbiome. Follow-up studies have even found an association between the use of artificial sweeteners and glucose intolerance, an outcome affiliated with the shift in gut bacteria. This has led to research on humans that also has noted an association between artificial sweeteners, metabolic outcomes, and changes in our gut microflora. Maybe it’s time to try to cut back on the fake stuff in favor of smaller amounts of real sugar.

Despite the popularity of high-fat diets, early research suggests that a diet rich in saturated and trans fat may not be so good for the gut. Studies in both animal and human populations have shown that a diet rich in saturated fat (like from butter or fatty cuts of meat) may increase the “bad” gut bacteria population and decrease the “good” bacteria. In contrast, enjoying more unsaturated fats such as olive oil, avocado, and nuts may help your gut.

Research has linked animal products, especially red meat, to an unfavorable microbiome. Studies suggest that red meat may reduce the beneficial short-chain fatty acids that help feed the bacterial community, promote the growth of “bad” bacteria, and potentially increase the risk of irritable bowel disease. We believe everything fits in moderation, so you don't need to quit meat cold turkey (pun intended), but we can all likely benefit from eating less of it.

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