Teenage girls and young women who are overweight have a higher chance of being
deficient in vitamin D, scientists have found in research that strengthens the
case for wider use of supplements.
The research shows that even in a sunshine-rich climate similar to Sydney's it
is possible for young people to lack the essential vitamin, which the body
usually produces from sun exposure.
Using scans to measure the women's body fat - not just their weight - the
scientists, from the University of Southern California in Los Angeles, found a
strong link between excessive body fat and low vitamin D levels.
It was possible low vitamin D could cause weight gain, lead researcher Richard
Kremer wrote in the Journal Of Clinical Endocrinology And Metabolism. It was
also possible that "body fat may contribute to low … levels by trapping vitamin
D in fat tissues".
Low vitamin D has been linked to serious health problems, including cancer,
diabetes and the bone disorder osteoporosis. But the Californian study found
bone growth was the same whether the women (all of whom were white and aged 16
to 22) were vitamin D-deficient or not.
Louise Baur, a pediatrician at the Children's Hospital, Westmead, said some
Australians were more at risk of vitamin D deficiency, particularly people with
darker skin or who wore a lot of clothing. She said evidence linking body fat
and vitamin D depletion was becoming stronger but warned: "There's nothing to
say that vitamin D supplementation will decrease your body fatness."
Rebecca Mason, a professor of endocrine physiology at Sydney University's Bosch
Institute, said in prehistoric times vitamin D stored in summer - when people
carried more body fat - might have been released into the blood during winter -
when the body used fat stores. But today, people who put on weight rarely lost
it again, meaning vitamin D might never be released.
Professor Mason said many people had low vitamin D levels and it was reasonable
for concerned individuals to take vitamin D pills.
