The Microbiome and the Hadza Diet
‘We are what we eat’. An oft uses phrase but it is appears to be true – literally.
Over recent years, scientists have been gathering evidence that our modern western diets are causing us to lose an important part of ourselves. According to research our microbiome – the huge collection of bacteria living on our intestines is becoming less diverse. This is important since our intestinal bacteria has such a great effect on our physical health and emotional well-being. The microbiome has a great influence on everything from your metabolism and immune system to your behavior and mood.
An Endangered Species
When we think of endangered species, we are more likely to think of large, exotic animals like pandas, rhinos or Siberian tigers. But there is an extinction event taking place much closer to home. So close in fact that you need not move an inch to witness it.
According to research done over the past few years, much of the bacteria that used to thrive in our ancestor’s bodies has already disappeared. It is apparent that modern Western diets as well as modern hygiene and medications have have already caused the loss of dozens of microbes from the digestive tract making our gut microflora less diverse and possibly far less healthy.
One of these missing microbes helped us to properly metabolize carbohydrates. Other bacteria lost to us acted as prebiotics while helped bolster our immune system health.
Back in 2009, a team of researchers led by Gloria Dominguez Bello – a microbiologist at New York University’s School of Medicine – set out to investigate just how much we have lost by analyzing the microbiome of a remote tribe in Venezuela.
Her team flew by helicopter to a very remote area of the country near its border with Brazil. Here they spent time with the Yanomami tribe whose hunter-gatherer lifestyles closely resemble the way our ancestors would have lived. The members of this tribe have lived in the same way for thousands of years far from the intrusions of modern life as we know it. In fact, the visit by the research team was the first time that this tribe had ever made contact with outsiders from the modern world.
The researchers took a fecal sample from 12 members of the tribe and returned to new York to analyze its contents – specifically to find it which species inhabited the guts of these indigenous people.
Although they were expecting a difference, the actual results surprised Domingues-Bello and her colleagues. They were shocked at just how diverse the content of the microbiome was and just how many differing species were present. According to the researchers, this remote tribe had around 50% greater ecological diversity compared with an average American.
The Hadza Diet and the Microbiome
The research carried out in South America paced the way for more studies culminating in a report published in July of this year. This time, the researchers led by Stanford University microbiologist – Justin Sonneberg, spent a year in Tanzania to analyze the microbiome of a tribe called the Hadza.
Like the Yanomami tribe from Venezuela, the Hadza are a tribe of hunter-gatherers with a lifestyle from a bygone age. Their diet is made up almost exclusively of food that they forage on the forest and includes fiber rich and highly nutritious berries, bananas and honey while any meat they eat is hunted and caught wild.
They eat none of the processed food so common in the modern Western diets neither do they eat food which came from a farm.
“They are a special group of people” says Sonnenburg. Only some 2,200 of the tribe remain and of that number even fewer – around 200 or so adhere exclusively to the hunter-gatherer lifestyle.
For around a year, the research team led by Sonnenburg analyzed 350 or so stool samples provided by the Hadza people. After that, they compared the bacterial species present in the Hadza with other bacteria taken from 17 distinct cultures in various parts of the world. These included the hunter-gatherers in Venezuela as well as other similar communities in Peru and subsistence farming communities in Cameroon and Malawi.
The trend that they found was crystal clear. The farther away a person’s diet gets from a modern Westerner’s diet, the more diverse the range of microbes that they have in their intestines. This includes number of bacteria that are completely missing from the modern American gut.
It does not matter where in the world that you live. What matters, is the diet and the traditional lifestyle. Whether you live in Africa, South America or Papua New Guinea, those people who retain their traditional lifestyle and diet have very similar gut microbes. Not only that, but their microbiome contains microbes that everybody in the modern, industrialized world is lacking.
What do the Findings Mean?
Clearly, a person’s diet plays a major role in which microscopic creatures will inhabit our digestive tract. These people from indigenous tribes do not sit down several times a day and eat large meals in the same way that we do. According to Dominguesz-Bello they eat small amounts throughout the day. When they feel like eating, they just grab some berries and bananas or fill up on fish soup and plantain.
The modern western diet is is largely deficient in fiber and high in processed junk, refined sugars and refined carbohydrates. The research strongly suggests that this diet is effectively wiping out many bacterial species from our digestive tracts.
This was the conclusion reached by Sonnenburg and his colleagues after they had finished analyzing the microbiome of the Hadza people. However, when they went back to examine more stool samples later in the year, they uncovered something they were not expecting to find.
The composition of the Hadza microbiome actually fluctuated over the course of the year depending upon the specific season and what the people were consuming during those seasons. Even more surprisingly, they found that at one time of year, the microbiome’s composition looked very similar to that of a Westerner.
Why the Microbiome Changes
As the seasons change, so does the diet of the Hadza. During the long dry periods, the Hadza people eat considerably more meat much like a Westerner. Their microbiome fluctuates as their diets change. Some species of bacteria prevalent during the wet seasons actually disappeared or their numbers fell to an undetectable level similar to that seen when analyzing the Western microbiome.
During the wet seasons, the Hadza’s diet changes considerably and they eat far more honey and fruit like berries. Eating these foods brings back the missing bacteria but the researchers remain uncertain of what exactly it is about these foods which brings back the missing microbes.
What Can We Do to Bring Back our Missing Microbes?
Lawrence David , a scientist studying the microbiome at Duke finds the research very exciting. According to David, the finding suggest that the changes in the gut microbiome may not actually be permananent and could be reversed through dietary choices.
So what dietary changes could help bring back our missing bacteria?
Lawrence David believes cutting the amount of fat in the diet may be key. The major shift between the Hadza’s wet season diet and the dry season was whether they were foraging for honey and berries or hunting for game.
Sonnenburg on the other hand thinks the key factor is fiber since fiber is vital for a persons microbiome.
According to Sonnenburg, researchers are beginning to understand that people that have a diet rich in fiber are feeding the microbiome.
The Hadza consume an enormous amount of fiber far in excess of the average Western diet. Their staple includes fiber rich fruit and tubers from the baobab trees which provide them with over 100 grams of dietary fiber each day. It is actually the equivalent of some 50 bowls full of Cheerios and some 10 times greater than most Americans consume each day.
According to Dominguez-Bello, as our diets become even more western and further removed from our ancestors, we lose many bacterial species. We are also starting to see a higher incidence of chronic illness related to our immune systems like Crohn’s disease, allergies and autoimmune disorders.
These studies are teaching us a lot and future planned research is likely to tell us more about ourselves and what we can do to prevent these illnesses and live a long and healthy life.