food, human conditions, medicine, microbes

What is a “Healthy” Gut Microbiome?

Which types of microbes are good to have in our guts — belonging to our gut microbiome — and which microbes shouldn’t be there for us to be healthy? It turns out that this is a very complicated question. Over the past couple of years, the gut microbiome has been found to be related to aging, as well as obesity, autoimmune diseases, infections, and other medical conditions. It’s clearly a crucial health-related factor.

hunter gatherers Hadza health
People of the Hadza hunter-gatherer community, which was recently found to have a unique, and diverse, gut microbiome. (Image credit: Idobi)

However, studies in humans have mostly only investigated correlations, making it difficult to figure out whether observed microbiome differences are the cause or the effect of certain medical conditions. Complicating matters even further, a study published last week suggests that microbe species we’ve thought are key to have to be healthy might not actually be necessary, and others we thought to be detrimental may, in fact, be harmless.

In the study, a community of hunter-gatherers in Africa had their gut microbiomes analyzed and compared to the gut microbiomes of urban dwellers (in Italy) as well as rural farmers (in Africa). The researchers found that the hunter-gatherers’ gut microbiomes were distinctly different from — and clearly more diverse than — both the urban dwellers’ and the rural farmers’ gut microbiomes. Of particular note, although they were in good physical shape, the hunter-gatherers didn’t have Bifidobacterium, a type of bacteria thought to be important for people to be healthy. (For example, when you eat chocolate, you may be feeding Bifidobacterium — they’re thought to make anti-inflammatory molecules, which may improve heart health and consequently reduce stroke risk.) Additionally, the healthy hunter-gatherers had relatively high levels of Treponema, a group of bacteria that’s thought to cause certain diseases, such as syphilis.

Clearly we have much to learn about our gut microbiomes and how they may affect our health. The authors of this recent study suggest that when assessing the health of a given gut microbiome, it may be more important to look at its level of diversity instead of specific species. A possible explanation for why the hunter-gatherers had the most diverse gut microbiomes is that they may be consuming a greater variety and/or number of unprocessed, raw foods — foods that are still rich in microbes. (This ties into another recent study that looked at the importance of city dwellers being exposed to rural microbes to promote a healthy immune system.)

So while it’s quick and easy to eat pre-packaged, processed foods, it may turn out that, for the sake of our gut microbiomes and our health overall, we may want to find more time to prepare salads and other meals that incorporate raw foods.

Check out the resources below for previous gut microbiome-related Bytes!

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