Vitamin D boosts calcium potency

• Main Author: Janet Raloff
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Gunnar; Iceland
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.582.6452; http://www.direct-ms.org/pdf/VitDPopularArticles/Rayloff Vitamin D Boosts Calcium Potency.pdf

Many older adults, especially women, face a constant battle to preserve their bones ' density. They pop dietary supplements and try to stick to menus with foods rich in calcium. Nevertheless, they can still develop osteoporosis, a condition characterized by brittle bones and a high risk of fractures. A new study shows that how much calcium a woman needs to keep bones strong depends largely on an individual's daily intake of vitamin D, the sunshine vitamin that's also in many fortified foods. Indeed, the new study finds that in a country where vitamin D intakes are high, women can reduce their daily calcium intake to about one-third of the officially recommended daily amount without compromising their bones' health, says Gunnar Sigurdsson, an endocrinologist at University Hospital in Reykjavik, Iceland, and a study coauthor. The rub: Few women in North America come close to getting the 400 to 600 international units (IU) of vitamin D per day needed to achieve this calcium-sparing effect (see Understanding Vitamin D Deficiency). Many women in Iceland do, Sigurdsson's team found, but largely because these people tend to subscribe to the age-old local practice of fortifying their diets with a daily dose of cod-liver oil. This oil is a rarity: a food naturally rich in vitamin D. The new study supports a trend seen in earlier studies: that as people consume more vitamin D, the efficiency with which their bodies absorb calcium from food improves, notes Boston University endocrinologist Michael F. Holick. However, he's skeptical about the applicability of numerical data from the new study to populations outside Iceland. Fortified milk is a primary source of vitamin D for many people in the