Vitamin D NIH Conference Experts Support Raising Upper Limit

Supplement trade groups support NIH conference experts' recommendations to increase vitamin D research for identifying an increased Tolerable Upper Intake Level and urge the scientific community not to delay in taking active steps to increase the UL.

"Nearly all of the world's leading vitamin D experts believe the current UL is too low - there is near complete consensus there," Dr. Andrew Shao, the Council for Responsible Nutrition's VP-scientific and regulatory affairs, said.

"Vitamin D and Health in the 21st Century," sponsored by the National Institutes of Health's Office of Dietary supplements and other health organizations, was held at NIH's Bethesda, Md. campus Sept. 5-6.

The current Tolerable Upper Intake Level for vitamin D, as set by the Institute of Medicine, is 2,000 IU, an amount that limits research into a possible revision of the UL and potential additional benefits from higher doses of the vitamin, experts say.

Research is limited while the UL is restricted to 2,000 IU because institutional review boards are reluctant to approve trials of higher amounts due to safety concerns, according to Dr. Daniel Fabricant, VP of scientific and regulatory affairs for the Natural Products Association and several experts at the conference.

"The policy has to be in place to where science can test new ground. [The current UL] is restrictive and that's unfortunate," Fabricant said.

CRN's Shao agreed, stating, "Science is an evolving process, but when you have the kind of consistent positive results that we've seen for vitamin D over the last several years, combined with a safety profile that shows no toxicity or adverse events at levels more than five-fold above the current IOM recommendations, you have to question why some are so conservative in their approach."

In addition to limits on vitamin D research, Shao also pointed out some other ramifications of the limited UL.

"The current UL is restrictively low - not only for research, but commercial development as well," he said.

Experts' recommendations to increase the daily reference intake from 400 IU "to something closer to 1000 IU/day is moot until/unless the UL is revised higher, the reason being that many companies refuse to add more vitamin D to their formula until that happens. It's not a safety issue, but a liability issue for them," he said.

"The expectation of 100 percent safety or zero risk is impossible for any substance, but it's as if that is what some [members of the scientific community] are looking for. In the meantime, others are suffering from inadequate vitamin D intake," Shao stated.

Although both trade groups' scientific execs were encouraged by the positive feedback from the conference on vitamin D's benefits on bone strength and the need for a higher UL, they expressed disappointment at the lack of attention to emerging research on the vitamin's positive effects against cancer (see ¹ (Also see "Report Links Vitamin D3 To Cancer Prevention, Calls For Replacing D2" - Pink Sheet, 10 Sep, 2007.)).

"There was a gap in the conference as we would have very much liked to have seen discussion go beyond bone health to include discussion of the emerging research on vitamin D and cancer," Shao stated.

However, both were quick to point out consumers should recognize vitamin D's benefits and not be confused by the conference's scientific debate.

"Let's be very clear: Vitamin D, especially when coupled with calcium, is a very good thing for the 25 million Americans suffering from or at risk of developing osteoporosis," Fabricant said in a Sept. 5 release.

"The myriad of remaining questions and research gaps listed by many speakers should not be construed by the public to mean the link between vitamin D (along with calcium) intake and bone health is somehow in question," Shao concurred.

To increase the UL and DRI for vitamin D, the Institute of Medicine's Food and Nutrition Board has to go through another round of review for the nutrient.

However, funding to continue the nutrient review process is "very difficult" due in part to budget constraints, so the time of the next round is yet to be determined, Shao said.

- Jessica Lake ([email protected])