Current dosing recommendations are not helping patients achieve optimal Vitamin D levels, two new studies have found.

Low levels of Vitamin D have been shown to be associated with a higher risk of having a cardiac event, like a heart attack or stroke. 

For this reason, treatment with Vitamin D pills or injections is being investigated as a possible preventative method in these patients.

However, two new studies from Intermountain Health in Salt Lake City found that achieving those levels often takes giving patients much more than the daily recommended dietary allowance of 600 to 800 International Units (IU). In some cases, patients needed more than 10,000 IU.

“Our findings here show that just giving patients some Vitamin D does not help them achieve optimal levels. 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,” said lead author, Heidi May, an epidemiologist at Intermountain Health.

The findings were presented at the American Heart Association’s Scientific Sessions 2023 in Philadelphia on November 12-13.

In the first analysis of the study, 632 patients were stratified into two groups, either receiving a general recommendation to discuss their Vitamin D treatment with their clinician, or a targeted Vitamin D treatment. 

Of the 316 treatment participants, nearly 90 per cent required some level of Vitamin D dosing. Of those, 86.5 per cent required more than 2,000 international units (IU) daily and 14.6 per cent required more than 10,000 IU daily.

In the second analysis of the study, the baseline characteristics of study participants are reviewed. All study participants had to have a cardiovascular event within 30 days of study enrollment. The trial will continue until 104 patients have another heart event, or if they die due to heart disease.

Researchers found that baseline Vitamin D levels were a median of 25 ng/mL, less than 20 ng/mL is considered deficient, and between 20 to 30 ng/mL is insufficient. Among those randomised to the treatment arm with a Vitamin D level under 40, 58.5 per cent of patients had a starting Vitamin D dose of 5,000 IU — again, well over the 600 to 800 IU US Recommended Dietary Allowance.

“These findings show that without taking a tailored approach to evaluating and dosing with Vitamin D, patients most likely will not see any results,” said Viet T Le, researcher and physician associate at Intermountain Health.

“If Vitamin D can help prevent heart attacks, we want to know it, but our findings are showing that you can’t just tell someone to take a single low supplement dose, then set it and forget it,” Le added.