Supporting Human Health: Riboflavin as a Novel Prebiotic Candidate
Prebiotics: a long history
The association between gut microbiota and human health was first proposed over 100 years ago. Since then, there have been extensive studies into the importance of diet in modulating the composition of gut microbiota. First introduced in 1995, the concept of the prebiotic is defined as “a non-digestible food ingredient that beneficially affects the host by selectively stimulating the growth and/or activity of one or a limited number of bacteria in the colon, and thus improves host health”.
There is, however, an ongoing debate about which food ingredients qualify as ‘true’ prebiotics, as only a small number of non-digestible carbohydrates meet the criteria. Prebiotic food research has also been limited in recent years, following a ruling from the European regulatory bodies that does not allow the word ‘prebiotic’ to appear on food products because its definition contains an inherent health claim.
In addition to non-digestible carbohydrates, several non-carbohydrate structures, such as polyphenols, minerals or vitamins have also been found to have a beneficial effect on the modulation of gut microbiota. Research has focused on riboflavin (vitamin B2) in particular, as it is a water-soluble vitamin that is readily taken up in the small intestine. Riboflavin can be obtained via a healthy diet, with a recommended daily allowance of 1.3 mg. However, there are doubts that dietary riboflavin in this concentration can reach the colon. Absorption mostly takes place in the proximal small intestine through an active, carrier-mediated, saturable transport process that is reported to be linear up to approximately 30 mg riboflavin in a meal. It can therefore be assumed that riboflavin is more likely to reach the colon when taken in high doses.
One study was recently carried out to determine whether a high concentration of riboflavin can limit the growth of Faecalibacterium prausnitzii, one of the most abundant and important bacteria in gut microbiota. A small group of adult volunteers were supplemented with 100 mg riboflavin for 14 days. The results showed that the number of F. prausnitzii per gram of feces increased during supplementation, while the number dropped again after a one-week washout period. It was also found that there was an increase in another group of anaerobes and a decrease in E. coli – indicative of an improvement of anaerobic conditions and redox state in the gut.
Although riboflavin does not provide a direct substrate for microbial fermentation, the findings show that it may beneficially modulate the composition of the gut microbiota by being metabolized and changing the gastrointestinal redox state. This research is leading the way for an increased role of nutritional intervention in supporting human health – particularly thanks to the anti-inflammatory effects of F. prausnitzii. Since irritable bowel disease (IBD) and Crohn’s disease are characterized by low levels of F. prausnitzii,6 these studies suggest riboflavin could be used as a therapeutic or a supportive agent in their treatment.
For more information on the use of micronutrients in higher doses beyond currently recognized health effects, read our whitepaper ‘Micronutrients for pharmaceutical applications’ here.