Foods to Boost Gut Bacteria

Cold potatoes

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Cold potatoes—that is, taters that have been washed, cooked, and cooled—are one of the best sources of resistant starch. Resistant starch is a prebiotic, a type of indigestible carbohydrate that acts like food for gut bacteria, encouraging the good bugs to grow and flourish. While resistant starch has many health benefits, one of its most promising aspects is its ability to increase insulin sensitivity, helping people reduce diabetes risk and even lose weight.

Kefir

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Think of kefir as yogurt's tangier but more powerful cousin. The drink is made by seeding milk with kefir "grains," which are tiny bundles of yeast and bacteria, and letting it sit. Over time the grains ferment the milk, producing a tart drink full of probiotics, or healthy bacteria. A 2013 study found that kefir can help relieve gastrointestinal problems and allergies and may even have a positive effect on heart health. One caveat however: Many commercial kefir drinks contain very high amounts of added sugar, which feeds bad bacteria in your gut, so make sure you read the label and ingredient list. These are sneaky signs you might be eating too much sugar.

Green bananas

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Most people go out of their way to avoid green bananas but there's good news for people who just can't wait until they're fully ripe. Green bananas are a rich source of prebiotics, particularly resistant starch. They also have a healthy dose of both soluble and insoluble fiber, vitamins, and minerals. The combo provides a feast for good gut bacteria and helps protect your heart and bones. Can’t get past the taste? Try them boiled or fried or sub some green banana flour in place of regular flour. Here's how sniffing bananas could help you lose weight.

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Kimchi

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Don’t let the name throw you—this Korean dish is not only tasty but a health superstar. Kimchi is made by fermenting vegetables with probiotic lactic acid bacteria, which gives it the same boost of healthy bacteria as other fermented foods, like yogurt. Plus, since it’s made from cruciferous veggies like bok choy and cabbage along with healthy spices like garlic and peppers, it provides a mega dose of vitamins, fiber, and antioxidants. One study found that kimchi helps protect against cancer, obesity, and constipation while lowering cholesterol, boosting brain and immune function, and even providing some anti-aging benefits. Here are other proven cancer-fighting foods.

Sauerkraut

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Sauerkraut is kimchi’s German cousin, a lacto-fermented brine filled with cabbage, carrots, and spices—not to mention plenty of healthy bacteria for your gut. And not only does it have similar benefits as other fermented veggies but a study done by William & Mary college found that eating a daily serving of sauerkraut helped significantly reduce social anxiety. The researchers believe it’s because more than 80 percent of the calming hormone, serotonin, is manufactured in our guts (not our brains!) and the good bacteria boosted serotonin production.

Chocolate

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Yes, it's true! Chocolate can help encourage the growth of healthy gut bacteria. A study published in the International Journal of Food Biology found that combining chocolate with probiotics magnified the benefits of both. The chocolate protected the bacteria as it passed through the stomach, making sure it was absorbed in the small intestine while the bacteria helped the body properly digest the chocolate, enabling it to extract all the micronutrients and antioxidants. Talk about a win/win! Here are more healthy reasons to eat chocolate.

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Garlic

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Everyone’s favorite way to get bad breath also has powerful gut bacteria-boosting properties. Garlic is not only Americans’ number-one favorite spice (after salt) but is also beloved by bacteria thanks to its rich supply of prebiotics, their preferred food. Raw garlic is the best source but for those who don’t like the burn (or who feel like kissing someone later); cooked garlic also works well—so well in fact that a study published in Food Science and Human Wellness found that eating it is an effective way to prevent many gastrointestinal illnesses. Here are more surprising benefits of garlic. Feeling motivated? Try these seven other foods that also boost gut health.

 

Of the cancers that affect both men and women, colorectal cancer is the third most common cancer in the United States and the second leading cause of cancer-related death. New research - published in the journal Cancer Research - suggests a very common food additive might play a role in its development.

A common food additive may promote colon cancer, according to a new study.

According to the Centers for Disease Control and Prevention (CDC), 136,119 Americans were diagnosed with colorectal cancer in 2013.
Risk factors for developing the condition include inflammatory bowel diseases (IBDs), such as Crohn's disease or ulcerative colitis.
What IBD and colorectal cancer have in common is an alteration in the gut microbiota.
An overview of recent scientific literature shows that changes in the microbiota have become increasingly associated with colorectal cancer.
This is why Dr. Emilie Viennois, assistant professor at the Georgia State University Institute for Biomedical Sciences, Atlanta, believes there might be a connection between a common food additive that alters intestinal microbiota and colorectal cancer.

"The incidence of colorectal cancer has been markedly increasing since the mid-20th century. A key feature of this disease is the presence of an altered intestinal microbiota that creates a favorable niche for tumorigenesis."

Dr. Emilie Viennois

Dr. Viennois has led a team of researchers to examine the effect of certain dietary changes in mice and cancer tumor development.

The role of intestinal microbiota in colorectal cancer

There are over 100 trillion microorganisms living in the gut, including bacteria, viruses, and fungi. The microbiota is made of the physiological interaction between the host's microorganisms and the ones introduced from the environment.
The microbiota is acquired during the first stages of life and varies with every individual. Having a diverse and balanced microbiota is crucial in keeping a healthy immune system.
Severe changes in the microbiota, either as a result of changing one's diet, lifestyle, or because of an infection, can alter the symbiotic relationship between the host microorganisms and the environmental ones, leading to IBD.
IBD promotes the formation of tumors in the colon. Low-grade inflammation, which has been associated with changes in the microbiota and metabolic disease, has also been observed in many cases of colorectal cancer.

Emulsifiers and IBD

Previous studies have hypothesized that since the mid-20th century, dietary emulsifiers might have been responsible for IBD.
Research by the team at Georgia State University research labs showed that low concentrations of two common emulsifiers - carboxymethylcellulose and polysorbate-80 - induced low-grade inflammation and obesity/metabolic syndrome in mice.
Normally the intestine is protected from a variety of harmful bacteria via the mucus structures that cover the intestines, keeping the harmful bacteria away from the epithelial cells that line the intestine.
But emulsifiers seem to help transport bacteria across epithelial cells.
Emulsifiers are detergent-like molecules added to modern processed food, and they are used to help water and oil mix, giving processed food a smooth texture.

Assessing the effects of emulsifiers in mice

A new study - led by some of the same researchers at the Institute for Biomedical Sciences at Georgia State University - hypothesized that emulsifiers affect the gut microbiota in a way that promotes colorectal cancer.
"The dramatic increase in [colorectal cancer] has occurred amidst constant human genetics, suggesting a pivotal role for an environmental factor," says Benoit Chassaing, assistant professor at the Institute for Biomedical Sciences.
The team fed mice the two most common additives have also been linked to low-grade bowel inflammation and metabolic disease: polysorbate 80 and carboxymethylcellulose.
The doses were replicated so as to mirror the proportions these emulsifiers are commonly added to human processed food.

Emulsifiers alter gut bacteria composition

Researchers found that an intake of emulsifiers severely alters the composition of the gut microbiota, and it does so in a way that promotes inflammation and creates an environment favorable for the development of cancer.
After suffering emulsifier-induced alterations, the bacteria in the gut displayed more flagellin and lipopolysaccharide. These two substances activate pro-inflammatory gene expression in the immune system.
Not only did emulsifiers alter the microbiotic environment in a way that is pro-inflammatory, but it also changed the balance between cell proliferation and cell death, which enhances tumor development.
The negative effects of consuming emulsifiers disappeared completely in mice that had no germs and therefore no microbiota. Researchers also transplanted microbiota from mice that consumed emulsifiers to germ-free mice, and this was enough to change the balance in the intestine's epithelial cells.
This further reinforces the central role that the microbiota plays in tumor induction and development.
This study demonstrates that emulsifiers induce alterations in the microbiome. These alterations are both necessary and sufficient for changing the balance in the intestinal epithelial cells.
Changes in epithelial cells are thought to cause the appearance and development of tumors.

These findings support the notion that changing the composition of gut microbiota causes low-grade inflammation in a way that promotes colorectal cancer.
The researchers are now further investigating specifically which microbiota are responsible for this effect, as well as the precise mechanism that promotes cancer.
Learn how colorectal tumors might be worsened by mouth microbes.

Written by Ana Sandoiu