Healthnotes Newswire (August 9, 2001)—The prevalence of vitamin D deficiency in healthy postmenopausal women is extremely high, according to a study published this month in the Journal of Bone and Mineral Research.¹

In this study, vitamin D nutritional status (as assessed by blood levels of 25-hydroxy vitamin D—a standard laboratory test) was determined in 161 postmenopausal Spanish women (average age, 61 years) who were referred for osteoporosis screening. Vitamin D levels were found to be below normal in 39.1% of the women. In women with osteoporosis, vitamin D levels were approximately 25% lower than in those with normal or marginally low bone density. Furthermore, women with vitamin D deficiency were more than four times more likely to have osteoporosis than were women with normal vitamin D levels. This study demonstrates that vitamin D deficiency is present in epidemic proportions among Spanish women, and is a risk factor for osteoporosis.

The high prevalence of vitamin deficiency in this study is surprising, considering that there is an ample amount of sunlight in Spain (sunlight exposure triggers the production of vitamin D by the skin). It should be pointed out that this study was conducted from November to April, a time during which sunlight exposure is comparatively low. Had the study been performed during the summer months, it is likely that fewer women would have been found to be vitamin D-deficient. Nevertheless, the apparent epidemic of vitamin D deficiency is disturbing, even if it is present during only half of the year.

Vitamin D is produced in the skin upon exposure to sunlight. It is also found in some foods, including fish, liver, and fortified milk. In many countries, fortified milk is probably the main dietary source of vitamin D. However, since vitamin D fortification of milk has not been mandated in Spain, sunlight is presumably the main source of this vitamin for Spanish women. In the United States and other countries where vitamin D is added to milk, the prevalence of vitamin D deficiency is lower, but is still present in up to 12.6% of elderly women living in the community and in more than half of patients hospitalized on a general medical ward.^{2 3}

Risk factors for developing vitamin D deficiency include lack of sunlight exposure, avoidance of vitamin D-containing foods (e.g., milk, liver, and fish), and diseases that cause malabsorption.

References:

1. Mezquita-Raya P, Munoz-Torres M, De Dios Luna J, et al. Relation between vitamin D insufficiency, bone density, and bone metabolism in healthy postmenopausal women. J Bone Miner Res 2001;16:1408–15.
2. Semba RD, Garrett E, Johnson BA, et al. Vitamin D deficiency among older women with and without disability. Am J Clin Nutr 2000;72:1529–34.
3. Thomas MK, Lloyd-Jones DM, Thadhani RI, et al. Hypovitaminosis D in medical inpatients. N Engl J Med 1998;338:777–83.

Matt Brignall, ND, is in practice at the Seattle Cancer Treatment and Wellness Center and at the Evergreen Integrative Medicine Clinic in Kirkland, WA. He specializes in integrative treatment of cancer. He is a contributor to Healthnotes Online and Healthnotes Newswire.