Under Your Skin and Into Your Gut
By BETH HARPAZ
If something gets “under your skin” — in other words, if you’re bothered by something — does it also get into your gut?
The question was posed by researchers looking at the “social epidemiology” of the human microbiome, meaning the trillions of microbes and their genes inhabiting the human body. “The mechanisms through which social and demographic factors shape the microbiome over the life course are not well understood,” according to the study published in Current Epidemiology Reports. Differences in microbiomes related to race, ethnicity, and socioeconomic status have been observed, but how those differences relate to health disparities deserves more attention.
The paper was co-authored by Professor Jennifer B. Dowd (Graduate School of Public Health & Health Policy) and Audrey Renson (University of North Carolina, Chapel Hill). They surveyed “nascent research … linking social factors to the microbiome including early life exposures, psychosocial stress, social relationships, the built environment, health behaviors, and socioeconomic status.”
Babies delivered by C-section, for example, acquire micriobiota found on skin surfaces and in the environment, rather than developing bacterial communities similar to their mother’s vaginal microbiota the way vaginally delivered babies do. C-section rates for white Americans have been decreasing, but for black Americans, they’ve been increasing. And breastfed babies have better gut bacteria than formula-fed babies, but African-American children are less likely to be breastfed.
Alcohol and drugs also impact microbiomes. Antibiotics are more likely to be prescribed to white children than other groups, and that can have a lasting negative effect on gut bacteria.
Diet is a known determinant of gut microbiomes, with animal fat and protein promoting bad gut bacteria, while fiber, fruits, vegetables, seeds, tea, cocoa, and wine promote good gut bacteria. Fiber intake is lower among black Americans and the poor than other groups.
People who share households often exhibit similar microbiomes. But in what might be the report’s ickiest finding, eating the same food isn’t the only reason your gut is like your partner’s or your parents’. Physical interactions and even household surfaces promote shared skin, oral, and fecal microbiota among families and others who live together.
Stress is a known disruptor of microbiomes, but more research is needed on the impact of adversity and economic inequality on what’s in our guts.