title: Vitamin D bioavailability: state of the art.
abstract: There has been renewed interest in vitamin D since numerous recent studies have suggested that besides its well-established roles in bone metabolism and immunity, vitamin D status is inversely associated with the incidence of several diseases, e.g., cancers, cardio-vascular diseases, and neurodegenerative diseases. Surprisingly, there is very little data on factors that affect absorption of this fat-soluble vitamin, although it is acknowledged that dietary vitamin D could help to fight against the subdeficient vitamin D status that is common in several populations. This review describes the state of the art concerning the fate of vitamin D in the human upper gastrointestinal tract and on the factors assumed to affect its absorption efficiency. The main conclusions are: (i) ergocalciferol (vitamin D2), the form mostly used in supplements and fortified foods, is apparently absorbed with similar efficiency to cholecalciferol (vitamin D3, the main dietary form), (ii) 25-hydroxyvitamin D (25OHD), the metabolite produced in the liver, and which can be found in foods, is better absorbed than the nonhydroxy vitamin D forms cholecalciferol and ergocalciferol, (iii) the amount of fat with which vitamin D is ingested does not seem to significantly modify the bioavailability of vitamin D3, (iv) the food matrix has apparently little effect on vitamin D bioavailability, (v) sucrose polyesters (Olestra) and tetrahydrolipstatin (orlistat) probably diminish vitamin D absorption, and (vi) there is apparently no effect of aging on vitamin D absorption efficiency. We also find that there is insufficient, or even no data on the following factors suspected of affecting vitamin D bioavailability: (i) effect of type and amount of dietary fiber, (ii) effect of vitamin D status, and (iii) effect of genetic variation in proteins involved in its intestinal absorption. In conclusion, further studies are needed to improve our knowledge of factors affecting vitamin D absorption efficiency. Clinical studies with labeled vitamin D, e.g., deuterated or (13)C, are needed to accurately and definitively assess the effect of various factors on its bioavailability.
authors.affiliation: a INSERM, UMR1062, Nutrition, Obesity and Risk of Thrombosis , Marseille , France.
authors.forename: P
authors.initials: P
authors.lastname: Borel
authors.forename: D
authors.initials: D
authors.lastname: Caillaud
authors.forename: N J
authors.initials: NJ
authors.lastname: Cano
mesh_terms: D000375:Aging / Q000378:metabolism; D001682:Biological Availability; D002762:Cholecalciferol / Q000493:pharmacokinetics; D019587:Dietary Supplements / Q000032:analysis; D004872:Ergocalciferols / Q000493:pharmacokinetics; D005227:Fatty Acids / Q000378:metabolism; D005527:Food, Fortified / Q000032:analysis; D006801:Humans; D007408:Intestinal Absorption; D007783:Lactones / Q000378:metabolism; D000077403:Orlistat; D012307:Risk Factors; D013395:Sucrose / Q000031:analogs & derivatives / Q000378:metabolism; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000378:metabolism / Q000493:pharmacokinetics*
chemical_list: D004872:Ergocalciferols; D005227:Fatty Acids; D007783:Lactones; D014807:Vitamin D; D002762:Cholecalciferol; D013395:Sucrose; C013692:sucrose polyester; D000077403:Orlistat; C104450:25-hydroxyvitamin D
keywords: 25-hydroxyvitamin D; Cholecalciferol; absorption; bioaccessibility; ergocalciferol; intestine