Prebiotics and the bioavailability of minerals and trace elements

Promising evidence exists for a stimulatory influence of prebiotic carbohydrates (non-digestible oligosaccharides (NDO) and lactulose) on the bioavailability of minerals and trace elements, although most information is available from rat experiments. Because the number of human studies is limited, additional research is needed, especially studies that focus on the long-term effects of prebiotics on bone metabolism. The hypothesized mechanisms suggest that prebiotics that result in a strong pH reduction, a pronounced osmotic effect, a stimulation of the exchange of protons, an increased level of butyrate and calbindin, and an enlarged surface area in the colon may be promising candidates for increasing the absorption of minerals and trace elements. Because the place of colonic fermentation seems to be of influence in these mechanisms, the use of mixtures of different types of prebiotics is of special interest. Probiotics are involved in most prebiotic-related mechanisms, possibly mediated in part by the production of polyamines. Therefore, the combined use of pre- and probiotics may yield promising results. More detailed information on the present state-of-the-art concerning the effects of prebiotics on the bioavailability of minerals and trace elements in different life stages, discussed by study design and its underlying mechanisms, can be found in this review.