The environment likely impacts the gut microbiome more than genetics. From your surroundings (like the presence of pollutants) to lifestyle changes (such as an altered diet), you can influence your gut flora. Read on to learn about these variables, plus how you can make them work for you to boost your wellness.
Key sources of environmental influences on the gut.
Diet
Researchers consider diet to be the most important environmental factor influencing the gut microbiome—with effects noticeable within mere weeks. A higher intake of fiber, especially non-digestible carbohydrates (NDCs), is particularly beneficial. Greater consumption of NDCs is associated with a greater amount of microbiota diversity and a larger population of beneficial bacteria—both good things when it comes to gut health. This makes sense, as “good” bacteria feed on undigested nutrients, especially carbohydrates.
Accordingly, studies have shown that populations and individuals whose diets include more fiber tend to have healthier gut microbiomes. As an example, a 2010 study1 comparing the gut microbiomes of children from Italy and Burkina Faso (in Western Africa) revealed higher levels of a beneficial bacteria in the African children, which researchers believe is possibly due to the higher levels of complex starches in their diet.
Similarly, scientists studied 60 members of the Hutterite community in North America2, noticing significant shifts in gut microbiota between the summer (when more produce, rich in complex carbohydrates, is consumed) versus the winter. In the summer, their gut flora featured more of the health-promoting bacteria, Bacteroidetes.
Unfortunately, the Western diet—which is high in refined grains and low in fiber—is strongly linked to negative shifts in the microbiome, including a lower diversity of microorganisms. So, it stands to reason that if you reach for lots of white-flour cakes and pastries during the winter holidays (instead of foods with complex carbohydrates, like fresh produce and steel-cut oatmeal), you could negatively impact your gut microbiome.
Pollutants
Chemicals from personal care products and air pollution can also affect the composition of the gut microbiome. As evidence, studies of mice exposed to cadmium, lead, and arsenic show negative changes, including reduced species diversity.
Temperature changes
Studies of mice have demonstrated that cold and heat exposure can alter the gut microbiome. Cold exposure possibly shifts the amounts of specific microorganisms and decreases overall diversity. However, some researchers believe these changes might be beneficial, helping mice adapt to cold environments, for instance by promoting the browning of adipose tissue (body fat) to support the animal’s production of heat. Similarly, animal research has shown that heat stress also has an impact, possibly reducing microbiome diversity.
Socioeconomic level
In the U.S., a higher socioeconomic level is associated with a greater diversity of microbiota. As evidence, researchers discovered discernible differences between the gut microbiomes of low-income children in Bangladesh versus middle- and upper-class American children. These findings are not surprising: many factors characterizing lower income communities (like lower fiber diets and higher exposure to pollutants) are associated with reduced diversity in the gut microbiome.
Make your environment work for your gut
Of all the environmental factors, we likely have the most control over our exposure to pollutants and our intake of healthful fiber. Here are some ways to cut down on the former and boost the latter.
Improve air quality
If you live in an area of the country with high air pollution, keep your windows closed. Buy an air purifier, ideally one with a CADR of 240 or higher (and a minimum of 180).
If you live in an area with high air quality, open your windows often to ventilate your home. You can also invest in an air filter to purify the air in your home when your windows are shut.
Try to buy all-natural personal care and household products (like hairspray, cleaners, and insecticides) without pollutants. When painting your home, use low-VOC paint.
After installing carpeting, painting, or bringing home new furniture, try to keep windows open, in case any materials off-gas, releasing toxic fumes.
Up the fiber in your diet
Eat several servings of fresh fruits and vegetables a day.
When possible, buy organic and scrub well. Then, when it’s palatable, leave the (fiber-rich) peel on. For instance, try unpeeled apples, kiwi, delicata squash, potatoes, and carrots.
Instead of cereal, opt for oatmeal, like old-fashioned or steel-cut.
If buying bread, purchase 100% whole-grain products.
Keep refined grain foods, like most cakes, pastries, and cookies, to a minimum.
Resources:
1 Fillipo et al. (2010). [Study on diet and gut microbiota]. Pubmed.gov
2 Davenport et al. (2014). [Study on seasonal influence on gut microbiome]. National Library of Medicine
Karl et al. (2018). [Review article on effects of environment on gut microbiome]. Frontiersin.org
Ahn, J., Hayes, R. (2021). [Study on effects of environment on gut microbiome]. National Library of Medicine
[Guide to air purifiers]. (2022). Consumerreports.org
