on January 13th, 2016 No Comments
A study conducted in mice raises suspicions that we humans may be halfway down the road to the permanent loss of friendly gut-dwelling bacteria who’ve been our constant companions for hundreds of millennia. That’s probably not good.
Virtually all health experts agree that low-fiber diets are sub-optimal. One big reason: Fiber, which can’t be digested by human enzymes, is the main food source for the friendly bacteria that colonize our colons. Thousands of distinct bacterial species thrive within every healthy mammal’s large intestine. Far from being victimized by these colonic cohabitants, we’d be hard put to live without them. They fend off pathogens, train our immune systems, help us digest food we’d otherwise be unable to use and even guide the development of our tissues.
From a news release I wrote about the new study, which was spearheaded by Stanford microbiology/nutrition explorers (and husband/wife team) Justin Sonnenburg, PhD, and Erica Sonnenburg, PhD, and published in Nature:
[Previous] surveys of humans’ gut-dwelling microbes have shown that the diversity of bacterial species inhabiting the intestines of individual members of hunter-gatherer and rural agrarian populations greatly exceeds that of individuals living in modern industrialized societies. … In fact, these studies indicate the complete absence, throughout industrialized populations, of numerous bacterial species that are shared among many of the hunter-gatherer and rural agrarian populations surveyed, despite those groups’ being dispersed across vast geographic expanses ranging from Africa to South America to Papua New Guinea.
Another piece of information: The proliferation of nearly fiber-free, processed convenience foods since the mid-20th century has resulted in average-per-capita fiber consumption in industrialized societies of about 15 grams per day. That’s as little as one-tenth of the intake among the world’s dwindling hunter-gatherer and rural agrarian populations, whose living conditions and dietary intake presumably most closely resemble those of our common human ancestors.
Perhaps the most significant sources of our intestinal bacterial populations is our immediate family, especially our mothers during childbirth and infancy. So, if our low-fiber diets are depleting our intestinal ecosystems, could that depletion get passed down from one generation to the next?