When humans eat, they do not only eat for themselves but for also for the future generations. According to findings by a study of several generations of mice, fiber intake does not only affect the microbiome of the individual but also of that individual's succeeding generations.
"This is a seminal study," microbial ecologist Jens Walter of Canada's University of Alberta explains. "The magnitude by which the low-[fiber] diet depletes the microbiome in the mouse experiments is startling."
Along with probiotics, much depend on fiber intake for the multitudes of microbes in the large intestine to thrive. When this supply decreases, survival of gut bacteria also declines. Although the early humans may have enjoyed much more fiber intake than today's official daily recommendations and current average daily consumption, this disparity may have been changing the landscape. Experts believe that this decline may be linked to the rise in such health disorders as obesity and such inflammatory bowel diseases as Crohn's disease and ulcerative colitis.
In the study, the research team confined the test mice in a sanitized, germ-free environment but gave them human gut bacteria through fecal consumption. As a result, for about 60% of the microbe population in the test subjects, the levels decreased to half. When these mice bred, their offsprings displayed much lower microbe diversity. This cycle went on for succeeding generations of the mice until not enough was left could be inherited or acquired through birth, nursing or, as a habit among mice, consumption of each other's waste.
The condition could not be altered for the later generations by simple reintroduction of fiber through high-fiber food. Instead, subjects from these generations actually required high-fiber diet to be paired with waste transplant from test subjects belonging to the high-fiber group.
"While we pass on relatively few changes in our human DNA for each generation, this study indicates that we are potentially passing on huge changes in our gut microbiome," Sonnenburg points out.
According to microbiologist Eric Martens of Ann Arbor's University of Michigan Medical School, "The surprise is that a proportion of organisms can actually be driven to extinction."
While other studies observed the low diversity of microbes in the guts of obese individuals compared to non-obese individuals, further study is needed to solidify the link of microbial decrease across generations in humans and the consequences to health.
"In these complex ecosystems it is very difficult to know the exact outcome of biodiversity loss," remarks Sonnenburg. She adds, however, that "it is likely these extinctions within the microbiota would have big effects."
In the meantime, a healthy diet with a sensible amount of food intake rich in nutrients and minerals should not go amiss. Beans and grains along with good probiotics are always winning choices for gut health.
