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Canadian adults are at risk
of a vitamin D deficiency and therefore more prone to osteoporosis and
fractures.
The findings, coupled with
those of other recent reports, indicate that the recommended intake of
vitamin D should be higher than the current 200 international units (IUs)
for adults in Canada and the United States.
Blood levels of vitamin D and
hormones that help to synthesize the vitamin were measured, but calcium
intake was not assessed.
More than one third of the
group had blood levels of vitamin D that fell below optimum levels at
least once during the year, but the actual proportion of adults with insufficient
blood levels of vitamin D may be even higher. The study relied on a conservative
threshold for vitamin D in the blood and was conducted in a city with
one of the highest levels of sunlight exposure in Canada.
Regardless of season, blood
levels of vitamin D were lowest among elderly adults, who are at higher
risk of the brittle-bone disease osteoporosis.
The findings support those
of other studies on adults living in countries at higher latitudes, where
people may not get enough wintertime sunlight to trigger the conversion
of the vitamin D precursor in the skin.
The darker a person's skin,
the more difficult it is for him or her to obtain adequate vitamin D via
sunlight.
Canadian
Medical Association Journal June 11, 2002;166:1517-1524 (Free full-text
article)
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