Dietary supplements contain not only macro- and microelements, but also elements which affect human metabolism. Many products available on the market contain chromium compounds together with chitosan used as a dietary supplement enhancing the digestionof lipids. The studies involved natural chitosan from krill available on the market, with the deacetylation degree of 85 to 95%, and dietary supplements containing chitosan (Vitana®, Hitec Nutrition®) as well as a product containing ionic chromium with niacin and several aminoacids – Chromdiet®). The study has determined the capability of binding fatty andbile acids by dietary supplements containing chitosan and chromium. The process of lipidsand bile acids adsorption was investigated by means of a dynamic method in a biopharmaceutical model imitating in vitro conditions. The findings prove that extracts of fatty acids and bile acids undergo adsorption by various kinds of adjuvant substances found in dietary supplements, which confirms a significant effect of these polymers on the bioavailability of fatty and bile acids in a human organism. The addition of chromium to a supplement does not effect the capability of chitosan to bind fatty and bile acids. Mean adsorption of bile acids by 1 g of the polymer (chitosan, inulin, fibre) ranges from 0.9 g to 1.79 g dependingon the pH (which decreases the bioavailability of lipids by 15-30%).