Grandpa's food makes our intestinal flora poor

The diet of our grandparents and parents also influences our microbiome

If our intestinal flora is depleted, this can also be a result of fiber-poor diet of our parents and grandparents. © thinkstock
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Inherited Shortcomings: If our gut flora is depleted, it may not be because of our own diet - we may have inherited the deficiency from our parents and grandparents. This is indicated by a study with mice. The fatal thing about it: The shortcomings in the important microbial community are partly irreversible. Eating rich in fiber alone is no longer enough to make up for this, according to the researchers in the journal "Nature".

Our intestinal flora is immensely important to us. Because it not only controls our appetite, it also protects against asthma and autoimmune diseases and even strengthens the immune system of our brain.

Only one tenth of the fiber

The prerequisite for this, however, is that the bacteria in our digestive tract get enough food in the form of fiber-rich fiber. Exactly those are however with our today's eating habits mostly in short supply. Thanks to ready meals and fast food, we only consume a maximum of one-tenth of the fiber that our hunter-gatherer ancestors still ate.

How this affects the intestinal flora, Erica Sonnenburg from Stanford University and her colleagues now in a trial with mice examined. These came from a sterile reared mouse strain without its own intestinal flora, but received shortly after birth, the bacteria of a human donor. One group of mice then got normal, fiber-rich food, while the second received extremely low-fiber food.

Fast foods and ready meals do not provide enough fiber to our intestinal flora. bhofack2 / thinkstock

"Scars" on the microbiome

As expected, the effect was clear: "Within a few weeks, we saw massive changes, " reports Sonnenburg. "The poorly-fed mice harbor fewer and fewer bacteria in their intestines." Several microbial species had disappeared completely, many others had lost three-quarters. display

In addition, this depletion of the intestinal flora was only partially reversible, as the researchers noted: even when the mice were again fed on fiber, their microbial community remained impoverished compared to the control animals. Around one third of the bacteria species did not reach the original amount and variety even after several weeks of fiber treatment. "The low-fiber diet left 'scars' on the microbiome, " said Sonnenburg and her colleagues.

Passed on to the great-grandchildren

But that's not all: this impoverishment of the intestinal flora even transcends future generations, as the experiment proved. To do this, the researchers intersected the poorly-fed mice and fed their offspring again with the "Civilization diet". Here they also tested whether the intestinal flora can recover through a dietary regimen.

The result: With time and with each generation, the microbial diversity in the intestine of the mouse continued to decrease das and that very clearly: The great-grandchildren of the original experimental mice were already missing nearly three quarters of the bacterial species. as the researchers report. Because the intestinal flora is transmitted to the offspring during pregnancy and birth and then further thinned out during their lifetime.

Irreversible loss

However, the unfortunate surprise came when the researchers examined whether and how well the dietary fiber treatment in these mice struck: as it turned out, the losses in microbial diversity in the subsequent generations were almost irreversible, Even with fiber-rich nutrition, two-thirds of the bacterial species disappeared permanently from their intestines - this part of the microbiome had finally died out over the generations.

Fruit, vegetables, cereal products USDA

Transferred to humans, this means: Our intestinal flora could already be irreversibly impoverished. "In the course of our history, we humans have changed our food several times - from farmers and collectors over the first farmers to today's industrially produced food, " said Sonnenburg and her colleagues. "And every change was probably associated with a corresponding adaptation of the intestinal flora."

Healthy food may not be enough

The low-fiber diet, which has increasingly established itself with us since the beginning of the 20th century, could have left unexplainable "scars" in our microbiome. We have already inherited a gut flora from our grandparents and parents, which is less species-rich than our ancestors.

And that has consequences: It may not be enough if we eat healthy and rich in fiber. If our parents and grandparents were unhealthy, we still have to bear the consequences. "There are only a few ecosystems in which a low biodiversity is a good thing - and we have no reason to assume that our gut is an exception here, " says Sonnenburg.

Help from outside bacteria

However, there is a way out, as the mouse experiment showed: Transmitted the researchers, the healthy, species-rich intestinal flora of the control animals via a faecal transplantation to the great-grandchildren of the impoverished line, then developed after two weeks, the full range of microbial diversity. Such fecal transmission would certainly be the last method of choice for us.

But according to the researchers could help, for example, if we would comply with a less rigid hygiene and quiet times after gardening or dog caressing the hand washing leave out. Because that gives useful bacteria from the earth or the dog the chance to supplement our impoverished microbiome. (Nature, 2016; doi: 10.1038 / nature16504)

(Stanford University Medical Center, 14.01.2016 - NPO)