Over the last 10 to 15 years, the understanding of the composition and functions of the human gut microbiota has increased exponentially. More importantly the research has discovered that there is a relation between the gut microbiota and human health. Our gut microbiota contain tens of trillions of microorganisms, including at least 1000 different species. One third of our gut microbiota is common to most people, while two thirds are specific to each one of us. That raises questions about what determines the composition and which composition is more beneficial for health. It also led to research trying to influence the composition of the gut microbiota towards more healthier profiles.
Obesity has been associated with altered gut microbiota and there is data implicating gut microbiota dysbiosis (=imbalance) in the pathology of diseases. In addition there is evidence showing the capacity of gut microbiota to extract energy from the diet and to influence host energy metabolism, stressing the role they may play in obesity. The researchers in this study hypnotized that the consumption of natural compounds might lead to a reshaping of the obesity-associated bacterial dysregulation and dysbiosis and as a result improve health. They selected pterostilbene as compound to try to induce such change.
In the experiment they fed rats with a standard diet supplemented with pterostilbene at a dose of 15 mg/kg body weight per day over a period of 6 weeks. Fecal samples at the beginning and at the end of the 6 week period were analysed as well as body parameters and tissue analyses. The research demonstrated that pterostilbene showed protective anti-obesity effects, improved metabolic function (insulin sensitivity) and induced structural changes in gut microbiota composition. A decrease in the levels of Firmicutes bacteria and an increase in Verrucomicrobia phyla was observed in the pterostilbene-treated group. Bacterial species belonging to genera Akkermansia and Odoribacter were also increased. In addition a strong inverse correlation between Akkermansia muciniphila and body-weight was found. The Odoribacter showed a negative correlation with adiposity.
The researchers concluded that the results demonstrate that pterostilbene modifies the intestinal bacteria composition towards a healthier microbial profile and suggest that the anti-obesity effects induced in the rats are associated with an enrichment of the mucin-degrading bacterial members, namely Akkermansia and Odoribacter genus.
While not part of this research it is interesting to note that the changed gut microbiota might also support in the production of Urolithin A, which was recently in the news when researchers discovered that it aids with the elimination of damaged mitochondria and as result leads to more energy production. Urolithin’s are produced by selected gut bacteria from ellagitannins which are part of nuts, berries etc. In this study it was observed that individuals with strong urolithin production had developed much higher amounts of Verrucomicrobia (Akkermansia muciniphila) compared to non-producers. In the study above pterostilbene supplemenation led to an increase in Akkermansia and one could therefore speculate it supports urolithin production.
Finally lets convert the rat dose to the Human Equivalent Dose (HED) using the FDA specified guidelines. The pterostilbene dose of 15mg/kg translates into a HED of approx. 2.4mg/kg. That means a dose of approximately 170mg pterostilbene per day for a person weighing 70kg. This is within dosing considered to be safe. Typical serving sizes of supplements on the market are 50mg.