Vitamin D routine supplementation recommended by Harvard researchers -- NEJM study.

VITAMIN D ROUTINE SUPPLEMENTATION "SHOULD BE CONSIDERED" because deficiency is widespread, linked to adverse effects and difficult to predict, Melissa Thomas, MD/PhD, Harvard Medical School, et al., conclude in a study on vitamin D deficiency in general medical inpatients. The researchers measured vitamin D intake, ultraviolet light exposure and risk factors for vitamin D deficiency in nearly 300 patients on a general medical ward at Massachusetts General Hospital and found that more than half were vitamin D deficient. The study, funded by grants from the National Institutes of Health and the American Kidney Fund, was published in the March 19 New England Journal of Medicine.

"Hypovitaminosis D is common in general medical inpatients, including those with vitamin D intakes exceeding the recommended daily amount and those without apparent risk factors for vitamin D deficiency," Thomas and colleagues state. "Maintaining vitamin D intake at the level of the current recommended daily amount or using multivitamins may not be sufficient to ensure adequate vitamin D stores," they continue. "Because of the potential adverse effects of vitamin D deficiency on the skeleton and other organ systems, widespread screening for vitamin D deficiency or routine vitamin D supplementation should be considered."

The researchers found 164 of the total 290 patients evaluated in 1994 were vitamin D deficient (57%), and 65 were "severely" deficient (22%). "Lower vitamin D intake, less exposure to ultraviolet light, anticonvulsant drug therapy, renal dialysis, nephrotic syndrome, hypertension, diabetes mellitus, winter season, higher serum concentrations of parathyroid hormone and alkaline phosphatase, and lower serum concentrations of ionized calcium and albumin were significant univariate predictors of hypovitaminosis D," Thomas et al. explain.

Even some patients who said they ingested the suggested amount of vitamin D were found to have low levels, possibly because they overestimated their intake. Thirty-seven percent of those ingesting more than the recommended daily intake were found to be vitamin D deficient; 66% of the patients who consumed less than the recommended level were deficient. Moreover, in a subgroup of 77 patients under age 65 (mean age 44) with no known risk factors for vitamin D deficiency, 42% were found to be deficient.

"A large number of patients with vitamin D intakes above the recommended daily amount were vitamin D deficient. Because milk products contain variable amounts of vitamin D, vitamin D intake may have been overestimated," Thomas et al. state.

"Previous estimates of the prevalence of hypovitaminosis D in outpatients were substantially lower than in our study," Thomas et al. note. "The higher prevalence of vitamin D deficiency in this study may be related in part to the relatively low solar intensity in New England or to the nature of our patients. Medical inpatients are more likely than outpatients to have conditions associated with vitamin D deficiency," they add. "However, 42% of our healthy subgroup were vitamin D deficient, providing evidence that these results are not attributable to severity of illness."

"Our data support the conclusion that the current recommended daily intakes of vitamin D, which were recently revised upward, may be insufficient," the researchers theorize. Recommended daily intake has been raised from 5 mcg for adults over age 51 to 10 mcg for those 51-70 and 15 mcg for those over 70 ("The Tan Sheet" Aug. 18, 1997, pp. 14-16).

"For example, a daily intake of 5 mcg of vitamin D was less effective in preventing bone loss than a daily intake of 20 mcg in postmenopausal women. Moreover, daily administration of 10 mcg of vitamin D in patients with high dietary calcium intakes did not protect against fractures, whereas 20 mcg of vitamin D per day plus calcium decreased the risk of fractures in elderly women with lower dietary calcium intakes."

A three-year Tufts University study published in the Sept. 4, 1997 New England Journal of Medicine found the combination of calcium and vitamin D supplementation reduced bone loss and fractures in older people ("The Tan Sheet" Sept. 8, 1997, p. 16).

In an editorial on the new study, Robert Utiger, MD, says "several steps should be taken to increase vitamin D intake. The recommended adequate intake should be increased further, encouraging nutritionists who advise people and plan meals in clinics, hospitals, and nursing homes to provide larger amounts of vitamin D and alerting physicians to the nearly universal need for more vitamin D." Utiger urges fortification of foods other than milk or cereal to target adults. Moreover, "the amount of vitamin D in supplemental multivitamins or calcium supplements should be increased substantially, and all adults should be advised to take them. A widespread increase in vitamin D intake is likely to have a greater effect on osteoporosis and fractures than many other interventions," he concludes.