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Vitamin A may thwart the ability of vitamin D to reduce risk of osteoporosis – June 2010

Vitamin D deficiency and high serum levels of vitamin A increase the risk of osteoporosis evaluated by Quantitative Ultrasound Measurements (QUS) in postmenopausal Spanish women.

Clin Biochem. 2010 Jun 17.
Mata-Granados JM, Cuenca-Acevedo R, de Castro MD, Sosa M, Quesada-Gómez JM.
Unit of Investigation, Development and Initiatives, Sanyres, Córdoba, Spain; Mineral Metabolism Unit, Endocrinology Service. Hospital University Reina Sofía. Córdoba, Spain.

OBJECTIVES: Association between vitamin D deficiency and excess of vitamin A as a potential risk factor of osteoporosis and fracture has been evaluated.

DESIGN AND METHODS: 232 healthy postmenopausal women were studied. Serum parameters were analyzed by standard methods and fat soluble vitamins by an own HPLC method. QUS measurement of the calcaneal bone was carried out by Sahara.

RESULTS: 124 patients were considered non-osteoporotic and 101 (44.9%) were osteoporotic.
The prevalence of high serum levels of retinol was 36.4% and vitamin D deficiency was 70.1%.
60.4% of women with vitamin D deficiency have high serum levels of retinol.
In the whole population, the increased risk of osteoporosis was up to three times higher for the highest retinol quintile, as compared with the lowest retinol quintile.
Whereas in women with vitamin D deficiency the risk of osteoporosis increased was up 5 times higher than women in the lowest quintile of retinol.

CONCLUSIONS: Our results show that high retinol levels together with vitamin D deficiency are hitherto an overlooked risk factor for osteoporosis.

See also VitaminDWiki