Gut response. These Hadza women have intestinal bacteria that Hadza men, probably because they eat a lot of rich tuberous root vegetable fibers.
Max Planck Institute for Evolutionary Biology
After taking an antibiotic or catching an intestinal bug, many of our belts down probiotic drinks restore the "natural balance" of bodies in the intestines. Probiotics are one of the food industry's most dynamic products now added to yoghurts, drinks and baby food. Still, not everyone needs to stay healthy. A new study of the gut bacteria of hunter-gatherers in Africa found that they completely lack a bacterium that is a key ingredient in most probiotics and considered healthy food. In addition, the Hadza are not suffering from colon cancer, colitis, Crohn's disease, or other diseases of the colon that are found in humans eating modern diets in western countries.
The new study is the first to report on the gut bacteria of hunter-gatherers who hunt and forage for most of their food, just as our ancestors did before invention of agriculture 10,000 years ago. So far, studies on intestinal bacteria have focused on people living in industrialized countries, many eat diets rich in sugar, salt and fat. These regimes have changed the type of bacteria in our guts, known as the microbiome. Gut bacteria react quickly to changes in the diet of their hosts, and humans who live in rural areas and eating less processed foods have more diverse microbiomes. Conversely, the researchers also found an association between less diversity in the microbiome and disease of the colon, such as Crohn's disease and colon cancer.
In the new study, an international team worked together to collect and analyze bacteria in stool samples from one of the last hunter-gatherers of the remaining communities in the world, the Hadza of Tanzania. As part of his thesis project, Stephanie Schnorr, a graduate student at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, had the unenviable task of asking the Hadza for fecal samples. But when the interpreter explained what she wanted, she got lucky when one elder, named Panda, said: "We normally give ground. We will give him instead. "
Once Schnorr had samples of 27 Hadza, aged 8 to 70, she sent them in frozen or dried at the University of Bologna in Italy, where a specialized team and extraction sequencing the DNA of bacteria. the team identified the bacteria using the DNA of the Hadza and also analyzed the type of nutrients in feces, including microbial metabolites, which are fatty acids that microbes use in the gut to get their energy. when they compared the DNA from the Hadza with those of the Italians, the team found that the Hadza have an intestinal ecosystem more diverse microbe. in addition, when they also examined these bacteria in two groups of farmers in Africa, they found that the Hadza were the only people who did not have a type of bacteria commonly added to probiotic drinks known as Bifidobacterium - Perhaps because it is associated with dairy products, the Hadza do not consume. The Hadza also had high levels of bacteria as Treponema , which is considered a sign of disease in Western populations because different types are associated with systemic lupus and periodontitis, and the syphilis. Yet Hadza experience almost no autoimmune diseases, obesity or diabetes, which are associated with imbalances in the various types of intestinal bacteria.
"We must redefine our notions of what is considered healthy and unhealthy, since these distinctions are clearly addicted to food," says Alyssa Crittenden, nutritional anthropologist at the University of Nevada, Las Vegas, and lead author of the study, which appears online today in Nature Communications .
other surprise is that Hadza men and women had significant differences in the type and amount of intestinal bacteria a sex difference ever observed before. the disparity reflects the sexual division of male Hadza hunting work and eat meat and honey, while women primarily dig tuberous plants. both sexes eat more what they see, and women eat more fibrous tubers. "We think that bacteria women are particularly good at digesting fiber," said Amanda Henry palaeobiologist of Max Planck. The team is currently testing the Hadza intestinal bacteria in laboratory studies to see if they are more efficient to break the fiber that Westerners of gut bacteria.
Other researchers also note that previous studies suggested that humans had less diversity in their gut microbiome on average than other primates. But this may be partly because researchers have not collected stool samples of human subjects eating different diets and living in a wide range of habitats. "This is a really important study because it helps us to find the range of variation in the microbiome in humans," says Steven Leigh biological anthropologist at the University of Colorado, Boulder.
This information will help researchers understand how our ancestors adapted to new habitats and diets that spread around the world because their intestinal bacteria co-evolved with them as their diet has changed. and it can be essential to understand that the spectrum diversity and how different species of bacteria interact with each other (and, perhaps, resist antibiotics) before consuming probiotic products on an "industrial scale", as if a single type, Leigh said.
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