Guidelines clarify controversies surrounding vitamin D

Miami Beach, Fla. - Vitamin D has been in and out of favor with physicians and their patients over the years. Even today, the controversies over the embattled vitamin still continue regarding its safe and beneficial daily allowance. According to the recent research, however, and guidelines from the Institute of Medicine (IOM), the majority of Americans are taking enough vitamin D.

These guidelines advise that a sufficient vitamin D level is at or above 20 ng/mL, which is in contrast to older guidelines that put it above 30 ng/mL.

The investigatory panel also set new guidelines regarding the recommended daily allowance of vitamin D and found that 400 IU for infants under 12 months old, 600 international units (IU) for children and adults younger than 70, and 800 IU for those older than 70 are not only safe, but beneficial in maintaining musculoskeletal health.

“Many people can benefit from supplements. According to the IOM report, a vitamin D supplement dosed at 600 IU a day is safe, and I think the data is pretty strong to support that,” says Martin A. Weinstock, M.D., department of dermatology, Rhode Island Hospital, Brown University, Providence, R.I.

Fulfilling daily intake

The three sources of vitamin D include synthesis in the skin after exposure to ultraviolet light, certain foods, and supplements.

The official recommended daily intake of 600 IU of vitamin D could be achieved through fortified food sources, particularly milk, but, according to Dr. Weinstock, most people today do not get anywhere near the recommended daily allowance this way.

“The main source of vitamin D is via ultraviolet light exposure from the sun. Clearly, we do not recommend for people to increasingly expose themselves to the sun for the sake of vitamin D synthesis because of the increased risk of developing skin cancer,” Dr. Weinstock says. “However, under normal circumstances, people are not completely protected from the ultraviolet rays of the sun and they do get a certain amount of sun during normal activities, boosting vitamin D synthesis and vitamin D levels.”

In those patients who are concerned about their vitamin D levels, Dr. Weinstock advises that vitamin D dietary supplements could be taken according to the new IOM guidelines, or vitamin D-fortified foods could be added and/or increased in their diet.

Patients who are concerned about potentially low levels of vitamin D have the option of taking a blood test to check their serum levels of 25-hydroxyvitamin D, the common measure of vitamin D status. Accordingly, the clinician can recommend dietary supplements or other methods to achieve normal levels of the vitamin.

Excess risk undefined

The main risk related to vitamin D excess would be supplementing with doses well above the recommended daily requirement, Dr. Weinstock says.

According to the new IOM guidelines, the “upper limit” for safe daily vitamin D intake is 4,000 IU. Some of the concerns regarding excess could include hypercalcemia and hypercalcuria, the possibility of renal stones, an increased risk of cancer or perhaps other adverse health outcomes, he says.

“Unfortunately, the risks of taking too much vitamin D are not very well defined. We need to better understand what those risks are and at what levels of vitamin D they start to apply in each patient,” he says.

The primary known benefit of taking vitamin D supplements is musculoskeletal health. Supplementation reduces the risk of falls and fractures, particularly among the elderly, he says. In concurrence with the latest IOM research, however, Dr. Weinstock says there is no strong evidence associating low vitamin D with various cancers, heart disease, diabetes and other conditions.

“This is an ever-changing field and I would suggest that physicians remain attentive regarding the newest literature on vitamin D. Given the amount of continued research regarding the effects of vitamin D, it is certainly plausible that these recommendations may change over time,” Dr. Weinstock says.

Disclosures: Dr. Weinstock reports no relevant financial interests.