The Endocrine Society's 2024 Clinical Practice Guidelines on vitamin D marked a significant departure from previous standards by eliminating specific blood level targets while acknowledging benefits beyond bone health.
In a review of the guidelines, by Michael F. Holick, MD, from Boston University School of Medicine, noted the new guidelines rely primarily on randomized controlled trials while excluding association studies that previously informed recommendations. This contrasts with the 2011 guidelines, which had specific target blood levels.
"If the pharmaceutical industry had developed a single drug capable of reducing cancer mortality by 25%, autoimmune disorders by 39%, and COVID-19 infection rates by 74%, it would be heralded as a miracle drug," said Dr. Holick in his analysis.
The 2024 guidelines recommend empiric vitamin D supplementation for targeted groups: children and adolescents aged 1 to 18 years (approximately 1200 IU daily), adults over 75 (900 IU daily), pregnant women (2500 IU daily), and individuals with prediabetes (3500 IU daily). For nonpregnant adults up to age 75, the new guidelines maintain the Institute of Medicine's Dietary Reference Intakes of 600 to 800 IU daily.
Clinical data cited in Dr. Holick's review demonstrated significant health impacts at higher vitamin D levels. Studies show maintaining serum concentrations above 30 ng/mL was associated with a 90% reduction in all-cause mortality. For COVID-19 outcomes, patients with 25(OH)D levels of 34 ng/mL showed a 54% reduced risk of infection compared to those below 20 ng/mL.
The guidelines did not address patients with underlying conditions affecting calcium, phosphate, vitamin D, and bone metabolism—populations previously covered by the 2011 guidelines. A key limitation noted in recent large vitamin D trials is that many participants had adequate baseline levels, potentially masking supplementation benefits in deficient populations, he noted.
Current population statistics reveal approximately 24% of U.S. adults aged 18 to 50, 22% aged 40 to 59, and 24% aged 60 and older had circulating concentrations of 25(OH)D below 20 ng/mL. In Europe, approximately 40% of children and adults have been found to have low vitamin D status.
For every 100 IU of vitamin D obtained, circulating concentrations of 25(OH)D increased by approximately 0.7 ng/mL. Association studies suggest maintaining 25-hydroxyvitamin D levels of at least 30 ng/mL, with a preferred range of 40 to 60 ng/mL, to provide maximum extra skeletal benefits.
Dr. Holick has received grants from CARBOGEN AMCIS and Solius Inc., consulted for multiple companies, and served on speaker bureaus for Pulse LTD, Sanofi, Abbott, and others. He also chaired the 2011 Endocrine Society's Vitamin D Guidelines.
