Only certain groups of people should take high doses of vitamin D

BOSTON — Most healthy adults under age 75 can get enough of the recommended daily intake of vitamin D, but some groups may need to take higher supplements, according to a 14-point clinical practice guideline from the Endocrine Society.

Speaking at the Endocrine Society’s annual meeting, ENDO 2024, experts said children, people over 75, those at high risk of prediabetes, and pregnant women should take “empirical supplementation” of vitamin D above the Dietary Reference Intakes (DRI).

However, given the lack of supporting evidence from clinical trials, the expert panel in the guideline recommended against routine 25(OH)D testing unless indicated. Journal of Clinical Endocrinology and Metabolism.

The DRI established by the US Institute of Medicine is set at 600 IU or 15 μg per day for most children and adults.

“These guidelines are intended to address vitamin D requirements for disease prevention in healthy adults who have no underlying conditions that impair vitamin D absorption or action,” noted guideline co-chair Marie DeMay, MD, of Harvard Medical School and Massachusetts General Hospital in Boston.

For this guideline, the committee searched for published research, with an emphasis on clinical trials, related to 14 clinical questions surrounding vitamin D, 25(OH)D testing, and disease risk reduction. The committee found:

• Vitamin D supplementation for adolescents aged 1-18 years is intended to prevent nutritional rickets and reduce the risk of respiratory infections (based on low evidence). Clinical trials on the basis of which this benefit was achieved used doses equivalent to 300-2,000 IU (7.5-50 μg) per day, averaging approximately 1,200 IU (30 μg) per day.
• In adults aged 75 years and older, excess vitamin D intake is associated with a reduced risk of death (moderate evidence). For this benefit, trials have used an equivalent range of 400 to 3,333 IU (10 to 83 μg) per day, with an average of 900 IU (23 μg) per day.
• Taking extra vitamin D may help delay the progression to full-blown diabetes in people with high-risk diabetes (moderate evidence). Vitamin D doses in clinical trials ranged from the equivalent of 842 to 7,543 IU (21 to 189 μg) per day, with an average of about 3,500 IU (88 μg) per day. Participants in some trials were able to continue taking their usual supplements containing up to 1,000 IU (25 μg) of vitamin D per day.
• Empirical supplementation may also help reduce the risk of preeclampsia, intrauterine death, preterm birth, small-for-gestational age, and neonatal death in pregnant women (low evidence). Doses in clinical trials ranged from 600 IU to 5,000 IU (15 to 125 μg) per day, usually given daily or weekly; the average was about 2,500 IU (63 μg) per day.

“In most cases, empirical vitamin D supplementation is inexpensive, feasible, acceptable to both healthy individuals and health professionals, and does not adversely affect health equity,” the guideline authors wrote.

For non-pregnant adults aged 50 years and older in whom supplemental vitamin D is indicated, the guidelines recommend low-dose daily vitamin D instead of high-dose daily vitamin D (low-quality evidence). The guidelines also recommend against empirical vitamin D supplementation in those under 50 years of age (very low-quality evidence) and routine vitamin D supplementation in those aged 50 to 74 years (moderate-quality evidence).

The guidelines recommend against routine 25(OH)D testing in the following populations, all of which are supported by “very low evidence”:

• All ages (Under 50, 50-74, 75 and over)
• During pregnancy
• Dark-skinned adults
• Obese adults

“There is no single question or answer about vitamin D,” said co-chair Anastasios Pittas, MD, of Tufts Medical Center in Boston. “As physicians, we are often asked, ‘What should we do about vitamin D?’, and we don’t know how to answer that question. There are a lot of questions, and it’s impossible for the committee to answer them all, so we have identified 14 questions that we believe may be clinically relevant about the role of vitamin D in disease prevention.”

This clinical practice guideline was jointly sponsored by the American Society of Clinical Endocrinology, the European Society of Endocrinology, the Pediatric Endocrinology Society, the American Society for Bone and Mineral Research, the Vitamin D Workshop, the American Academy of Nutrition, the Brazilian Society of Endocrinology and Metabolism, the Society of General Internal Medicine, and the Endocrine Society of India.