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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    • "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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    ABSTRACT: Bone homeostasis is maintained through a balance between osteoblastic bone formation and osteoclastic bone resorption. Aging induces bone loss due to decreased osteoblastic bone formation and increased osteoclastic bone resorption. Osteoporosis with its accompanying decrease in bone mass is widely recognized as a major public health problem. Nutritional factors may play a role in the prevention of bone loss with aging. Among various carotenoids (carotene and xanthophylls including beta (β)-cryptoxanthin, lutein, lycopene, β-carotene, astaxanthin, and rutin), β-cryptoxanthin, which is abundant in Satsuma mandarin orange (Citrus unshiu MARC.), has been found to have a stimulatory effect on bone calcification in vitro. β-cryptoxanthin has stimulatory effects on osteoblastic bone formation and inhibitory effects on osteoclastic bone resorption in vitro, thereby increasing bone mass. β-cryptoxanthin has an effect on the gene expression of various proteins that are related osteoblastic bone formation and osteoclastic bone resororption in vitro. The intake of β-cryptoxanthin may have a preventive effect on bone loss in animal models for osteoporosis and in healthy human or postmenopausal women. Epidemiological studies suggest a potential role of β-cryptoxanthin as a sustainable nutritional approach to improving bone health of human subjects. β-Cryptoxanthin may be an osteogenic factor in preventing osteoporosis in human subjects.
    Journal of Biomedical Science 04/2012; 19(1):36. DOI:10.1186/1423-0127-19-36 · 2.76 Impact Factor
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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] "
    Contemporary Aspects of Endocrinology, 11/2011; , ISBN: 978-953-307-357-6
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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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    ABSTRACT: Recently, the laparoscopic sleeve gastrectomy (LSG) has become popular as a single-stage procedure for the treatment of morbid obesity and its co-morbidities. However, the incidence of micronutrient deficiencies after LSG have hardly been researched. From January 2005 to October 2008, 60 patients underwent LSG. All patients were instructed to take daily vitamin supplements. Patients were tested for micronutrient deficiencies 6 and 12 months after surgery. Anemia was diagnosed in 14 (26%) patients. Iron, folic acid, and vitamin B12 deficiency was found in 23 (43%), eight (15%), and five (9%) patients, respectively. Vitamin D and albumin deficiency was diagnosed in 21 (39%) and eight (15%) patients. Hypervitaminosis A, B1, and B6 were diagnosed in 26 (48%), 17 (31%), and 13 (30%) patients, respectively. Due to inadequate intake and uptake of micronutrients, patients who underwent LSG are at serious risk for developing micronutrient deficiencies. Moreover, some vitamins seem to increase to chronic elevated levels with possible complications in the long-term. Multivitamins and calcium tablets should be regarded only as a minimum and supplements especially for iron, vitamin B12, vitamin D, and calcium should be added to this regimen based on regular blood testing.
    Obesity Surgery 11/2010; 21(2):207-11. DOI:10.1007/s11695-010-0316-7 · 3.75 Impact Factor
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