Recommendations for daily vitamin D intake may be too low to
prevent deficiencies in some women, according to a recent study.

The study found that during the winter, many women in Canada had
insufficient blood levels of vitamin D despite consuming in their
milk or dietary supplements more than 200 international units
(IU) daily, the recommended intake for adults younger than 50
years of age.

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 latitudes means that
dietary intake becomes even more crucial to prevent rickets in
children and osteoporosis in adults.

During the winter, at least 20% of the 800 women in the study had
low blood concentrations of vitamin D, even if they had been
consuming 200 IU or more 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 that contained some vitamin D.

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, the researchers said.

Low vitamin D levels are a side effect of our modern lifestyle
because we spend most of our time indoors and often wear
protective clothing or sunscreen when we are outside, thus
shielding ourselves from the sunlight needed by our bodies to
produce vitamin D.

Vitamin D is a hormone-like substance that beneficially
influences numerous vital functions in your body. If your levels
are low, your health is at risk.

However, don’t consume mega-doses of vitamin D unless you are
under a doctor’s supervision. Vitamin D may be toxic in extremely
high doses or if your liver function is impaired.

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