The new insight stems from Australia and it centers on the availability of intestinal nitrogen to the microbes found in the gut. Nitrogen regulates the interactions between these microorganisms and the human host. Nitrogen availability can be affected by the different diets that people adopt.
Factors that shape this include food composition, eating pattern and genetic background. The research team, from the University of Sydney’s Charles Perkins Center, are closer to understanding the causality between various types of diet and their effect on the host’s microbiome. The microbiome refers to the totality of microorganisms within a given niche (in this case the human intestinal system).
This was the outcome of a study conducted using mice. Here 858 mice were subjected to 25 different diets. The diets varied in terms of protein, carbohydrate and fat content. With these diets, the levels of different microbial species either increased or decreased. Where fat was not significant, the proportions of carbohydrates and proteins were, and ratio between the two was influential.
The reason for this is because carbohydrates contain no nitrogen but protein does, so variations in food affect the microbial composition. The general finding is that a good level of carbohydrate is helpful for promoting gut bacterial diversity and this correlates with a healthier metabolism. One important point the researchers note is that diet and the benefits are likely to be host dependent (that is effects of different diets will differ for different people).
The new study lays out the foundation for future modelling so that the effect of different diets on the ecology of the gut can be tracked. This is important since the microbiome of the human gut is related to different health outcomes, such obesity and various metabolic diseases. The term “metabolic” means the biochemical processes involved in the body’s normal functioning.
For example, it has been established there is a type of diet more strongly associated with a higher risk of heart disease. This diet is one made up of red meat, eggs and high-fat dairy products. Here when foods rich in animal fats are digested in the gut a harmful chemical called TMAO (trimethylamine N-oxide) is formed as a by-product of the process.
It is hoped, in the long term, those dietary combinations that promote the best outcomes for each of our gut microbiomes will be identified. Thus the inference from the research is, according to Professor Andrew Holmes who was in charge of the research team, “there are many different diet strategies that claim to promote gut health, and until now it has been very difficult to establish clear causality. Such findings could be significant in relation to people recovering from major surgery or who are seriously ill. Some research studies suggest that the right balance with the microbial composition of gastrointestinal system is important for the recovery rate of patients.
The new research is published in the journal Cell Metabolism. The research paper is headed “Diet-Microbiome Interactions in Health Are Controlled by Intestinal Nitrogen Source Constraints.”
In related news, to explore the cause and effect in relation to the microbiome, so that different variables can be manipulated, researchers based at the University of Luxembourg have been exploring the use of an artificial gut to allow different experiments to be run.
This article is part of Digital Journal’s regular Essential Science columns. Each week Tim Sandle explores a topical and important scientific issue. Last week we profiled how nanotechnology can help with the introduction of safer cosmetics. The week before we discussed whether fungi become more pathogenic in space, and if this phenomenon poses a risk to astronauts.
