Keep your gut bacteria happy by eating more of these 5 food groups

In 2020, comfort foods came to the rescue: Faced with crisis, people used nostalgic foods and familiar food cravings to soothe their anxieties. As the pandemic progressed, we consumed more pizza, hamburgers, ice cream, french fries, and macaroni, according to one survey conducted in July.

New research suggests sticking to these eating patterns may not bode well for our gut health, and may correspond with an increase in dangerous, inflammatory bacteria. As a result, if 2020 was the year of chronic comfort eating, then 2021 could be the year of chronic inflammation. But there is a way out: By avoiding certain food groups now, the billions of gut bacteria that live inside of you could flourish and safeguard your health long term.

In a new study published in the journal Gut, researchers evaluated the gut microbiomes of 1425 people. They found that people who ate more of certain foods had more markers of inflammation and that these patterns were consistent across groups with intestinal diseases. Other food groups, however, were linked to higher levels of protective and anti-inflammatory bacteria.

Among other patterns, the study identifies vegetables, plant-based foods, and fish as being linked to beneficial, “commensal” bacteria. These kinds of bacteria, in turn, are tied to lower levels of inflammation and nutrient metabolism. Conversely, people whose diets were rich in animal-based foods, processed foods, and sugar had more markers of inflammation and higher levels of problematic bacteria that can cause disease.

Laura Bolte is one of the lead authors of the study and a researcher at the University of Groningen in the Netherlands. She tells Inverse that her study ties the digestive system to our health as a whole.

“Our study suggests that the gut microbiome could be one potential link between diet and disease risk,” she says.

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HOW THIS AFFECTS LONGEVITY — Inflammation is a broad term that encompasses many different reactions in the body. Generally, inflammation occurs as a physiological response to threats, like pathogens, invasive objects, or even sunburn. We might feel feverish or tired, experience redness and swelling, or feel pain as our immune system tackles the threat.

But these inflammatory immune cells can overreact and fight the body’s own cells. This is what happens in conditions like arthritis, psoriasis, and intestinal problems like Crohn’s disease and ulcerative colitis.

Over a long period of time, chronic inflammation may be related to many of the conditions that lead to serious health issues and often, death — cardiovascular problems, for example.

The new study suggests that by adjusting our diet, we might be able to minimize the presence of microbes related to inflammation and increase beneficial bacteria, even if our gut microbiome is unhealthy to begin with.

“[This] may be relevant to other diseases in which inflammation, gut microbial changes, and nutrition are a common thread,” Bolte says.

She said that in cancer, obesity, and liver cirrhosis, for example, there’s a decrease in bacteria with anti-inflammatory properties. If we could boost the good bacteria while also minimizing the bad, then that is good news for our health overall, and for minimizing the toll that inflammation can take on us in old age when our bodies’ systems become more vulnerable.

SCIENCE IN ACTION — Scientists analyzed 1,425 stool samples collected from people in the northern Netherlands. The participants were divided into four groups: “healthy controls,” people with irritable bowel syndrome, people with Crohn’s disease, and people with ulcerative colitis. All three of these conditions are associated with inflammation in the digestive system.

All of the participants completed a detailed questionnaire about their eating habits over the month prior to the study. The researchers analyzed the stool samples using DNA extraction to find the microorganisms, and then identified and determined how abundant certain microbes were in each sample using specialized software.

The researchers identified patterns of bacterial species in the samples and then compared these patterns to the foods the participants had reported eating, as well as the gut composition between groups.

WHY IT'S A HACK — This study adds to what was already known about the links between chronic inflammation, gut health, and diet. For example, Western diets were already associated with inflammation underlying certain diseases, including type-2 diabetes and liver disease. Mediterranean diets, or diets high in legumes, fish, vegetables, and nuts meanwhile, are linked to a lower risk of irritable bowel syndrome, and many people follow this kind of diet to reduce symptoms of Crohn’s disease.

This study draws direct, clear connections — or at least, strong associations — between certain foods and bacteria populations with known roles in our health. Some of the most compelling links were these:

• Processed foods and animal-derived foods were linked to more pro-inflammatory bacteria known as “opportunists.” These bacteria can cause disease under certain conditions.
• Meat, mayonnaise, french fries, and soft drinks were consistently linked with a group of “unfriendly” bacteria. These bacteria can erode the mucus membrane of the gut lining if they don’t have enough fiber to feed on.
• Nuts, fruit, fish, vegetables, cereals, and red wine were linked to higher numbers of gut-friendly bacteria that create “short-chain fatty acids.” These acids help reduce inflammation and protect the gut lining.
• Coffee was strongly associated with a bacterium known as Oscillibacter — a kind of probiotic with anti-inflammatory properties.
• Low fat, fermented dairy products were linked with higher populations of lactic acid bacteria, which also have well-established health benefits.

The patterns were consistent and applied not just “healthy” people, but also to those living with some of the most difficult to treat digestive problems.

“What was surprising was to see such a clear association between what we consider a healthy diet and a healthy gut microbiota composition,” Bolte says.

Ultimately, eating more of these five food groups may be the key to safeguarding gut health and combating harmful inflammation:

1. Nuts
2. Whole grains
3. Fish
4. Vegetables and other plants
5. Fermented dairy

What this study does not establish is how long one would have to sustain a certain diet for their gut composition to transform, Bolte says. And what might be beneficial for people in the northern Netherlands may not be exactly what works for everyone else.

But the results do provide yet more evidence to suggest diets higher in legumes, nuts, grains, fish, and vegetables could boost longevity and prevent the kinds of inflammation that characterize myriad chronic diseases.

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