Body–Mouth Connection

We are what our microbes eat. The intimate relationship between diet, the gut microbiome and overall health

Do we have any control over our microbes?

All our bodily systems are connected, and we can’t look at one part of the body without considering others. In fact, the microbiome plays an important part in regulating our immune system, metabolism, mood, and preventing inflammation and diseases throughout the body. 

Dr. Daniela Weiler, oncologist at the Lucerne Hospital and specialist of nutritional medicine, told us in a Curaden Academy webinar on the microbiome and nutrition how a balanced, diverse and rich microbiome is a wonderful ally for our health. 

But do we have any control over our microbiomes? Can we in any way shape our ally to be as helpful as possible for us? To some extent, yes – we have a powerful key for influencing our gut microbiome: nutrition. As Dr. Daniela Weiler stated: the saying “we are what we eat” should definitely be revised. We are also what our microbes eat!

Different foods bring different microbes

Since the late 70s scientists have been observing that the way we eat has a clear influence on which microbes populate our gut. Experiments showed that a change in diet can induce large, temporary shifts in our microbiota within 24 hours. More stable alterations happen in one week. Here, we’ll look at some examples.

Researchers from the University of California comprehensively described, in a paper published in the Journal of Translational Medicine, how people following a diet rich in plant proteins and fibres have a diverse and increased number of bacteria, with some of those microbes being very helpful for the functions of our whole body. Bifidobacterium and Lactobacillus bacteria, for example, are able to digest – through fermentation – fibres and complex carbohydrates that end up in our big gut as our small gut cannot absorb them. In return, these microbes manufacture the short chain fatty acids.

Would you like to find out more about the connection between nutrition and microbiota? Watch the Curaden Academy webinar with Dr. Daniela Weiler.

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Short chain fatty acids like acetate, propionate and butyrate are incredibly beneficial: they trigger the formation of cells that suppress inflammatory responses, stabilising our immune system and promoting homeostasis. Essentially, they balance the whole system. 

The same research paper by the University of California described how, conversely, a diet high in animal protein and fat increases the number of bacteria that are bad for us – like the Bacteroides and Enterobacteria. These bacteria spark the inflammatory responses of our immune system and consequently raise the risk of diseases such as inflammatory bowel disease, obesity and autoimmune diseases. Micro-organisms linked to this type of nutrition are also lower in number and diversity, thus leaving space for opportunistic and pathogenic microbes to settle.

Which microbiome do you want with you?

In short, there are different types of microbiome that live in symbiosis with us, many of which help us in staying healthier. However, others do not – to the point of them even representing a threat to us. The good news is that, to some extent, we have the power to shape the composition of our microbiome.

Mediterranean diet

According to Dr. Daniela Weiler, foods that are particularly beneficial for our microbiome – ergo for us – are those of the Mediterranean diet. Olive oil, various fruits and vegetables, cereals, legumes, nuts, moderate consumption of fish and red wine, and a lower intake of dairy products, red meat, processed meat and sweets. This is the menu that promotes a vibrant and diverse community of microbes in our gut – which leads to improved overall health.

Oral health: one more key to the shaping of our gut microbiome?

The community of micro-organisms living in our mouth – the oral microbiome – counts about 700 different kinds of microbes, and is one of the most complex microbial communities in the human body. We already know that some of our oral-health habits can impact the composition of this community. For example, toothpastes containing enzymes and proteins can augment natural salivary defenses and increase the bacteria associated with gum health. 

Can oral health have an impact on the gut microbiome too? Scientists are investigating in this direction as recent studies have shown how bacteria populating our mouth are linked to the intestinal microbiome: they can colonise the intestines and persist there while other bacteria involved in gum disease are associated with both colon and pancreatic cancer.

Can I just have a quick look in your stomach?

Since the close relationship between diet, the microbiome and our overall health has become clearer, it has become increasingly important to know which microbes populate our gut. What are they? How many are they? And how do they vary according to our habits? 

To answer that, two interesting citizen science projects were created: the American gut and the British gut projects. Samples sent by volunteers are sequenced by researchers, and the data is then anonymously aggregated. The aim is to uncover the microbial content within the guts of the American and British populations – precious information that will tell us how lifestyle choices and diet influence our microbiome.

The two projects are still ongoing, but among the results to date, there is already a surprising one: eating about 30 different plants a week significantly boosts the diversity of your microbiome. Would you accept the challenge?

This article is part of a series about microbiota and its connection to all aspects of the human body, including oral health. If you would like to learn more about this topic, have a look at other articles from the series: