Vitamin A: Is It a Risk Factor for Osteoporosis and Bone Fracture?

J Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, 711 Washington Street, Boston, MA 02111, USA.
Nutrition Reviews (Impact Factor: 6.08). 11/2007; 65(10):425-38. DOI: 10.1301/nr.2007.oct.425–438
Source: PubMed


Results from observational studies of the association between vitamin A intake or serum concentration and bone mineral density or fracture are mixed. The inconsistencies may be due, in part, to difficulties in obtaining an accurate assessment of vitamin A intake or status. Serum retinol is a poor measure of vitamin A status because it is subject to homeostatic control. Stable-isotope-dilution methodology gives a validated assessment of the total-body and liver vitamin A stores and is recommended in future studies on vitamin A status and osteoporosis. The potential for exacerbating an already serious public health problem with intakes of vitamin A currently considered safe indicates further research into this matter is warranted.

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Available from: Jeffrey B. Blumberg
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    • "Vitamin A (retinol, retinal, and retinoic acid), which is formed from carotenoids in animal and human, has been shown to have a role in the regulation of bone cells and it may have an anabolic effect on bone [14-16]. However, vitamin A is also known to have a detrimental effect on bone at high doses [17-20]. In laboratory animals, high levels of vitamin A lead to accelerated bone resorption, bone fractures, and osteoporotic bone lesions [17]. "
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    • "increases in vitamin A might promote skeletal abnormalities. Some studies have shown that increased vitamin A intake or elevated serum retinol levels [Michaelsson et al. 2003] are associated with an increased incidence of hip fracture or decreased bone mass [Melhaus et al. 1998, Feskanich et al. 2002, Promislow et al. 2002]; however, other studies have shown no deleterious effect on bone mass or fracture risk, and, in some instances, protection from bone loss because of increased vitamin A has been reported [Ribaya-Mercado and Blumberg 2007, Caire-Juvera et al. 2009]. In studies where vitamin A analogues have been evaluated, decreases in bone mass have been reported following isotretinoin and acitretin usage in some instances, but a recent, large scale, case-control study has found no increased risk of fracture with these agents [Vestergaard et al. 2010] "

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    • "An excess in serum vitamin A can lead to ataxia, alopecia, dry skin, hepatotoxia, hepatomegaly, and might have an effect on bone metabolism by increasing bone resorption [27, 28]. Furthermore, high serum levels of vitamin A can be harmful in pregnant women due to the teratogenic effects on the fetus [13, 29, 30]. The serum levels in our patients, however, did not exceed 4 μmol/L after 1 year. "
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