Results of a study conducted by Intermountain Health in Utah suggest that the current U.S. Recommended Dietary Allowance (RDA) of 600-800 IU per day is often insufficient to elevate serum vitamin D to optimal levels.¹ The findings, from a trial in patients with a history of acute coronary syndrome, were presented at the American Heart Association’s Scientific Sessions 2023 on November 12 and 13.

“Our findings here show that just giving patients some vitamin D does not help them achieve optimal levels,” stated lead author Heidi May, PhD. “If researchers are going to further look at vitamin D dosing as a possible way to improve heart health, patients need to be given the right doses to reach those ideal levels.”

The current study analyzed data from a trial that investigated whether achieving desirable vitamin D levels through personalized management of vitamin D intake would improve cardiovascular outcomes. Three hundred sixteen participants were given vitamin D3 if their serum 25-hydroxyvitamin D level was lower than 40 ng/mL. An equal number of control group participants received a recommendation to discuss their vitamin D with a clinician, with 40 ng/mL as a goal.

Among the group that received vitamin D, only 13.5% were able to reach the target serum levels when given a 2,000 IU daily dose; over half required 5,000-8,000 IU per day; and 14.5% required over 10,000 IU per day. Fewer than 65% of treated participants reached the targeted vitamin D levels of 40 ng/mL at three months and 25% needed six months to achieve the study’s goal of greater than 40 ng/mL.

In addition to demonstrating the need for higher dosages of vitamin D, the study’s findings also emphasize the importance of using blood tests to guide vitamin intake. “These findings show that without taking a tailored approach to evaluating and dosing with vitamin D, patients most likely will not see any results,” Viet T. Le, DMSc, PA-C, of Intermountain Health explained. “We need to be far more intentional in how we’re treating patients with vitamin D beyond just telling them to take a vitamin capsule.”