Gut bacteria in Hadza diet different from ours study finds

Probiotics are one of the fastest growing areas for research as well as one of the valued members in the food industry. These are healthy bacteria or friendly bacteria that are added to yogurts, drinks, and baby food in order to colonize out gut when we are taking antibiotics or are down with an intestinal infection.

A new study in the journal Science has revealed that gut bacteria of hunter-gatherers in Africa did not actually contain any of these bacteria that are considered healthy.

An unidentified Hadza bushman with bow and arrow during hunting on February 18, 2013 in Tanzania. Image Credit: erichon / Shutterstock
An unidentified Hadza bushman with bow and arrow during hunting on February 18, 2013 in Tanzania. Image Credit: erichon / Shutterstock

The researchers also found that these original hunter gatherers did not get the common gut ailments that plague today’s mankind such as inflammatory bowel disease or Crohn’s disease, ulcerative colitis and colon cancer. This new study is the first of its kind that reports the gut bacteria composition of hunter-gatherers who used to forage or hunt for most of their foods.

These hunter gatherers mimic our ancestors before the invention of agriculture 10,000 years ago. Up until now the study of gut flora was restricted to persons living in industrial areas who eat processed foods rich in salts, sugars and trans fats. This study reveals that these processed diets have changed the composition of the gut bacteria or microbiome from the early cavemen.

An international team led by researchers at the Stanford University School of Medicine, came together to work on this study. The fecal samples of persons of one of the last remaining hunting and gathering communities in the world, the Hadza people of Tanzania were gathered for the study.

Justin Sonnenburg, PhD, associate professor of microbiology and immunology at Stanford and senior author of the multi-institution study called the Hazda population the closest available “proxy” to a time machine that researchers can climb onto in order to look at the eating habits of our ancestors.

There are around 1,000 Hazda existing of which only around 200 follow the old diet. Their diet comprises of five items that include meat, berries, baobab (a fruit), tubers and honey. The diet varies with season since storage of food and its availability throughout the year is not an option in the Rift Valley.

During dry seasons, meat, baobab and tubers are consumed more while berries, tubers, honey and baobabs are taken more during wet seasons. These 200 people would be lost soon said Sonnenburg and it is now that their guts and their ecosystem could be studied.

The team collected samples from 350 samples from 188 Hadza, aged 8 to 70 years over a roughly one-year period that were analyzed in University of Bologna in Italy, where extraction and sequencing of DNA from bacteria was done to identify their exact types. The fecal matter revealed the kind of foods the Hazda ate and the components of their microbial gut flora. The metabolites or fatty acids that are used by the microbes in their gut for energy, were also found in the samples. This was then compared with samples from Italians who ate normal western diet.

Results revealed that the Hazda had a more diverse gut microbial system. Further, two groups of farmers from Africa were also studied. The Hazda still came out to be different. Their samples did not show the presence of a type of bacteria commonly added to probiotic drinks—known as Bifidobacterium. This bacterium is usually present in milk.

Since the Hazda did not consume milk, they did not have these bacteria speculate researchers. The Hazda population was found to be free from several diseases including obesity, diabetes, autoimmune diseases etc. which are all thought to occur due to imbalances of the gut microbiome.

Alyssa Crittenden, a nutritional anthropologist at the University of Nevada, Las Vegas, and lead author of the study, said that this study changes the definitions of what is considered to be healthy and what is not. Healthy and unhealthy clearly depend on the diet. Hadza men and women also differed in their gut microbial environment found the study.  

This pointed towards the fact that diet was different for men and women. Hadza men hunt and eat meat and honey while women ear tubers that they have dug up. This difference has never been noted in the western population.  Paleobiologist Amanda Henry of the Max Planck said that women had bacteria that are better suited to digest the excess fibres that they were taking.

The study was funded by the National Institute of Diabetes and Digestive and Kidney Diseases, the Emch Family Foundation, the Forrest & Frances Lattner Foundation, the C&D Research Fund and the Discovery Innovation Fund.

Dr. Ananya Mandal

Written by

Dr. Ananya Mandal

Dr. Ananya Mandal is a doctor by profession, lecturer by vocation and a medical writer by passion. She specialized in Clinical Pharmacology after her bachelor's (MBBS). For her, health communication is not just writing complicated reviews for professionals but making medical knowledge understandable and available to the general public as well.


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