Study: Healthy Adults Unlikely to Benefit From Excess Vitamin D

A recent Clinical Practice Guideline issued by the Endocrine Society announced that healthy adults under the age of 75 are unlikely to benefit from exceeding the daily intake of vitamin D that was recommended by the Institutes of Medicine (IOM). However, individuals who could benefit from a higher dose than the recommended daily allowance include children, pregnant individuals, adults older than 75 years of age, and those with high-risk prediabetes, according to study authors.¹

Image credit: Cozine | stock.adobe.com

Vitamin D is a fat-soluble vitamin that is often found in foods like salmon, mackerel, and sardines. However, the vitamin is also offered as a dietary supplement to ensure proper levels in the body. Vitamin D aids calcium absorption in the gut while maintaining sufficient serum calcium and phosphate concentration, to ensure normal bone mineralization. When an individual does not have appropriate vitamin D exposure, they can experience thin, brittle, or misshapen bones.²

In contrast, extreme amounts of vitamin D could be detrimental to an individual’s health, resulting in toxicity. This is because the vitamin increases calcium absorption in the gastrointestinal tract, which could result in hypercalciuria—presenting symptoms of nausea, vomiting, muscle weakness, neuropsychiatric disturbances, pain, loss of appetite, dehydration, polyuria, excessive thirst, and kidney stones, according to researchers.²

In the current guidelines, the researchers provided recommendations for the use of vitamin D and testing for vitamin D levels among healthy individuals, without signals for vitamin D treatment or testing, according to study authors.¹

“The goal of this guideline was to address the vitamin D requirements for disease prevention in a generally healthy population with no underlying conditions that would put them at risk of impaired vitamin D absorption or action,” said Marie Demay, MD, of Harvard Medical School and Massachusetts General Hospital in Boston, in a news release.¹

The study authors noted that the recommendations did not suggest the intake of vitamin D supplements that are beyond the suggested dietary intakes that are highlighted by the IOM, among healthy individuals under 75 years old. However, the researchers found that a select few of individuals would benefit from exceeding the IOM dose recommendation. This included children and adolescents 18 years and younger to prevent nutritional rickets and protect against respiratory infections; individuals 75 years and older to lower mortality risk; pregnant individuals to reduce birthing risks; and individuals with prediabetes.¹

The guideline also noted that individuals aged 50 years and older should take a lower-dose vitamin D daily, rather than a non-daily higher dose. The study authors do not recommend routine testing for 25-hydroxyvitamin D levels in any of the populations studied.¹

Participants included in the clinical trials that informed the guidelines were reported to have adequate vitamin D blood levels at the start of the study. The study authors noted that this could have created limitations as the trials were not intended for several reported outcomes.¹

References

1. Endocrine Society Guideline recommends healthy adults under the age of 75 take the recommended daily allowance of vitamin D. EurekAlert! News release. June 3, 2024. Accessed June 6, 2024. https://www.eurekalert.org/news-releases/1046515.

2. Pharmacist Medication Insights: Signs of Taking Too Much Vitamin D. Pharmacy Times. News release. May 26, 2022. Accessed June 6, 2024. https://www.pharmacytimes.com/view/pharmacist-medication-insights-signs-of-taking-too-much-vitamin-d.