The numerous different bacteria that inhabit the human body are often referred to as our gut flora, gut microbiota, and also as our gastrointestinal microbiota. The composition of our gut flora is unique to each of us, kind of like our fingerprints. These bacteria found all throughout our digestive tract have some really important functions that have a direct impact on our health.

What are the functions of gut flora?

Of course, one of the functions of our gut microbiota is to ensure our body has good digestion overall. But there are also certain types of food that would be impossible to even digest if there were no bacteria in our gut. These food types would pass undigested through the stomach and small intestine; it is the job of gut bacteria to help us digest these foods in order to extract their nutrients. Another function of gut bacteria is to help the body produce vitamin B and vitamin K.

Gastrointestinal bacteria are also responsible for maintaining the intestinal mucosa that might be under attack from time to time by other microorganisms that inhabit our digestive tract. And our gut flora plays an important role in keeping our immune system ready to fight off any diseases.

The Diversity of Gut Flora

Our gut flora is made of complex bacterial communities made up of a great many completely different bacteria. One recent study confirmed that numerous cultural factors, especially diet, are critical in shaping the composition of our gut flora. Different diets result in completely different gut flora; even the continent you live on can affect the makeup of your gut microbiota.

Did you know that everything you eat and drink has an effect on gut flora?

Another recent study confirmed that everything we eat has an effect on our gut bacteria. One of the aspects of this large-scale study was to determine the exact effects of different foods on the human gut bacteria. Some of the findings are very interesting.

For instance, a diet that regularly includes buttermilk and yogurt increases the diversity of gut flora. The same goes for coffee and wine. The opposite is true of diets that include whole milk, or which are high in calories and fats; all of these can have deleterious effects on the diversity and number of our gut flora.

This study helped researchers identify over 50 food types that have a direct impact on gut flora diversity. Researchers refrained for drawing specific conclusions from the results, but the first author of this research, Alexandra Zhernakova, did say: "…there is a good correlation between diversity of gut flora and health: greater diversity is better."

What are the effects on our health when we are on a diet without a diversity of nutrients?

A study published in Molecular Metabolism reveals that health is compromised when we are on a diet that doesn’t contain all of the different nutrients that our body needs. They say that reduced diversity of nutrients has an effect on the diversity of our gut flora, thus also affecting our health. Numerous studies have proven that people with type 2 diabetes, obesity, or inflammatory bowel disease all have a reduced diversity of bacteria

Are restrictive diets bad for health?

Some of the bacteria inhabiting our intestines require specific nutrients in order to survive in their habitat. By going on a restrictive diet, we may inadvertently eliminate from our diet a food that is a primary source of nutrition for some of the bacteria in our gut flora. This will end up starving that bacteria, to the point they may die out altogether in our gut.

Studies have shown that temporarily excluding some nutrients does indeed result in a reduction of gut flora diversity. Worse, these studies also discovered that prolonged restrictive diets can result in great losses of gut flora, and sometimes in such a way that the losses cannot easily be reversed.

This study has also found that intermittent fasting may cause our gut flora to use nutrients found in protective layers of our intestines, which leads to colitis and metabolic syndrome. This is why it is important to always work with a professional nutritionist before going on a diet. The same goes with dietary supplements, which are often used rather haphazardly by many.

While a restrictive diet – such as keto, Atkins, paleo – may be tempting to try if you are looking to lose weight, the negative impact to your gut isn’t worth it given how important a healthy gut is to our overall health. Any diet which requires you to severely restrict what you eat is potentially robbing your gut microbiota of the nutrients it needs to stay alive and healthy.

 

Resources:

Diversity, stability and resilience of the human gut microbiota: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3577372/

Diverse diets enrich gut microbes:  http://www.medicalnewstoday.com/articles/308017.php

A healthy gastrointestinal microbiome is dependent on dietary diversity: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4837298/

Lifestyle has a strong impact on intestinal bacteria, which has a strong impact on health: https://www.sciencedaily.com/releases/2016/04/160428151853.htm