Vitamin D guidelines may be too low for women

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Vitamin D guidelines may be too low for women

By Suzanne Rostler

NEW YORK, Dec 11 (Reuters Health) - Recommendations for daily vitamin D

intake may be too low to prevent deficiencies in some women, researchers

report.

Their study found that during the winter, many women in Canada had

insufficient blood levels of vitamin D despite consuming more than 5

micrograms (mcg) or 200 international units (IU) daily, the recommended

intake for adults younger than 50 years of age, in milk or dietary

supplements. Vitamin D, which helps the body to absorb calcium, is added

to milk and is also made by the body when skin is exposed to sunlight.

But a lack of sunlight in northern countries such as Canada means that

dietary intake becomes even more crucial to prevent rickets in children

and osteoporosis in adults, explain Dr. R. Vieth from Mount Sinai

Hospital in Toronto, Ontario, and colleagues.

" Nutritional laws have been grossly wrong about adult needs for vitamin

D, " Vieth told Reuters Health, citing a previous study showing that

adults need at least 1,000 IU to ensure adequate blood levels of vitamin

D.

The current report is published in the December issue of the European

Journal of Clinical Nutrition.

The researchers measured blood levels of vitamin D in nearly 800 women

aged 18 to 35 over the course of a year, and surveyed them about their

food and multivitamin intake.

During the winter, low blood concentrations of vitamin D were not

related to low vitamin D intake, results show. For instance, 21% of

women who consumed no vitamin D were found to have insufficient blood

levels of the vitamin, compared with 26% of women who reported some

vitamin D intake and 20% of women who said they consumed more than 5 mcg

of vitamin D daily.

During the summer, however, women who took multivitamins had higher

blood concentrations of vitamin D. The researchers explain that women

who were physically active and engaged in outdoor activities where they

were exposed to sunlight were also more likely to take multivitamins.

A woman's race did not affect her vitamin D levels in wintertime but

during the summer, fewer white women had insufficient blood levels of

the vitamin.

People with darker skin are at greater risk of vitamin D deficiency

because they need more sunlight to trigger the reaction in the skin that

makes vitamin D. However, all women could benefit from more vitamin D in

the diet regardless of their skin tone or country of residence, Vieth

said.

" Low vitamin D levels are simply a side effect of the modern lifestyle

in most countries, whether people live in sunny places or not, " the

researcher added.

SOURCE: European Journal of Clinical Nutrition 2001;55:1091-1097.