Vitamin D sales soar as studies link a deficiency to a host of conditions

Amy McDonald, 34 weeks into her second pregnancy with gestational diabetes, was in for a routine checkup in Bala Cynwyd: blood pressure (fine), fetal heartbeat (loud), review of home blood-sugar monitoring (time-consuming).

A lab test for Vitamin D had come back low on a previous visit, and McDonald was now taking supplements.

"Any problems with the Vitamin D?" asked her doctor, Daphne M. Goldberg, who had recommended at least 10 times the dosage in federal guidelines. (No problems.)

Most women don't hear about Vitamin D during prenatal visits. Indeed, studies linking widespread deficiency of the "sunshine vitamin" to a host of seemingly unrelated conditions - among them heart disease, arthritis, depression, psoriasis, influenza, and several types of cancer - have been coming so fast and furious that government guidelines can't keep up. No one even knows what a "normal" level should be.

Many people aren't waiting. Sales of the supplement in the United States were an estimated $425 million in 2009, up 82 percent from the previous year and 10 times what was spent in 2001, according to the Nutrition Business Journal.

An authoritative federal review due next month is expected to raise recommended amounts. But scientists on the panel, whose guidelines will affect medical practices, fortified foods, and everyday consumer purchases, are likely to be cautious. Most major research findings on Vitamin D are recent, and the amount required to overdose has not been definitively shown.

Some prominent scientists argue that such thinking is backward. Vitamin D, which is naturally produced in the skin in reaction to sunlight, is far more benign than a pharmaceutical. And with Americans spending more time on computers indoors and less time without sunscreen outside, surveys show that at least half - and up to 90 percent - do not have enough.

"We have this vast experiment going on," said Carol L. Wagner, a neonatologist at the Medical University of South Carolina in Charleston. "We are looking at the rampant Vitamin D deficiency throughout the country."

Continuing the status quo, she said, will harm far more people than would higher doses of a vitamin that her research has shown to be safe.

Wagner cowrote American Academy of Pediatrics guidelines that two years ago doubled the recommended Vitamin D intake for children to 400 IU (international units) a day and said obstetricians should consider screening all pregnant women for deficiency.