How our day-to-day food intake shapes our gut microbiota

Diet is a major modulator of changes in gut microbiota composition, especially at an individual level. Other than diet, however, food metabolism and lifestyle variations (from levels of physical activity to sleep patterns) can all affect gut microbial communities. Most studies currently investigating diet’s relationship with gut microbiota rely on subjective responses from food questionnaires to assess what people eat.

A varied diet is an effective way to ensure good health for our gut microbiota

The study under focus in this post, which was led by Dan Knights at the University of Minnesota, aimed to explore how the gut microbiota responds to diet every single day.

For 17 consecutive days, 34 healthy participants were asked to self-record their food consumption using a food report. The team, meanwhile, collected fecal samples from participants on a daily basis, in order to analyze the gut microbiota.

After seeing the results, the researchers explained that gut microbiota variations correlate with food items when food is considered as a whole, but do not correlate when the food items are broken down by nutrient. Let’s take a simple example of a green leafy vegetable such as spinach, which is rich in iron. In addition to iron, spinach contains a multitude of nutrients, such as fiber, minerals and carbohydrates. All of these elements—the whole—therefore strengthen spinach’s relationship with the microbiome and have an impact on gut microbiota composition.

With this in mind, nutritional advice should focus more on recommending people combine fruit and vegetables in their daily diet instead of prioritizing specific fibers.

In a second part, the researchers confirmed that the microbiome’s response to food varies between individuals (previous studies in 2016 and 2018).

Tailored dietary advice may be the future for nutrition as we try to find a way of developing a healthy gut

The authors explain this result in several ways. For instance, our intestinal morphology (size of the intestines, quantity of secreted molecules) varies, resulting in a change in the way our body metabolizes food and elicits different responses from the gut microbiota. For example, if your body easily absorbs a large amount of protein from meat, less residual protein is accessible for your gut bacteria, which, in turn, will not be able to develop. Inversely, if your body does not absorb protein, bacteria feeding off residual protein will grow.

These findings therefore highlight the importance of moving from a “one-size-fits-all” dietary approach to an approach based on personalized gut microbiome treatments that will improve not only gut wellbeing, but also overall health.

In a further observation, in two participants, the consumption of “shakes” with the same nutritional composition for 17 days did not lead to a stable gut microbiota. This infers that gut microbiota stability is accentuated by the consumption of a varied diet. And if stability, richness and diversity are the three main characteristics of a healthy microbiome, having a diverse diet is a positive way of ensuring your gut microbiota is in good shape.

In conclusion, a diverse diet helps maintain a stable microbiome, while also giving your body all the nutrients it needs to stay healthy. Furthermore, tailored dietary advice (instead of a universal diet for everyone) may well be the future for nutrition as we try to find a way of developing a healthy gut.

Reference:

 Johnson AJ, Vangay P, Al-Ghalith GA, et al. Daily sampling reveals personalized diet-microbiome associations in humans. Cell Host Microbe. 2019; 25(6):789-802. doi: 10.1016/j.chom.2019.05.005.