The sun shining in the blue sky.

Study raises questions about the best way to assess vitamin D status

									Charlie Plain |
																			October 13, 2015

Aside from a good excuse to lay in the sun, adequate vitamin D intake is important for everyone’s health. It not only regulates calcium and phosphorus absorption, promoting healthy bones and teeth, it helps protect against multiple diseases.

The sun shining in the blue sky.
Credit: Stanley Zimny

“You’re constantly hearing about the potential health benefits of vitamin D in the news. This has caused a dramatic increase in vitamin D supplement use,” says School of Public Health epidemiologist and assistant professor, Pam Lutsey. “Thirty-six percent of U.S. adults report taking a vitamin D supplement either as a prescription or in a multivitamin.”

The increase in vitamin D supplement use is due to the chronically low levels of blood vitamin D concentrations in Americans. Previous studies show roughly 28 percent of caucasian Americans have vitamin D deficiency and black Americans at an alarming rate of 81 percent.

Prior research findings in the New England Journal of Medicine suggested blacks and whites have the same amount of bioavailable vitamin D (the portion of 25(OH)D that is not bound to vitamin D binding protein), which occurred due to blacks having lower levels of both vitamin D binding protein and 25(OH)D.

However, new research, published in Clinical Chemistry and the New England Journal of Medicine, co-authored by Lutsey and John Eckfeldt, professor in Laboratory Medicine and Pathology, contradicts the hypothesis of the previous NEJM study, using a new method for measuring the binding protein of vitamin D, developed by co-author, Andy Hoofnagle, at the University of Washington.

“The Powe paper was really transformative in the way everyone was thinking about vitamin D,” says Lutsey. “It offered an explanation — a beautiful explanation — for why we’re seeing these unexpected race interactions — but it was wrong.”

In their new studies, the authors demonstrate that vitamin D binding protein levels do not vary by race. The research provides experts with some clarity regarding vitamin D binding protein but also leaves many questions.

“So much is yet unknown. People are being prescribed vitamin D widely, yet at this point in time it’s not clear what biomarker is best for assessing vitamin D status, or what is the right blood concentration for optimal health — we need to figure that out,” says Lutsey.

~ Post originally published by Aliki Vrohidis on AHC’s “Health Talk

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