- Preliminary results from an ongoing clinical trial suggest that current vitamin D dosing recommendations are insufficient to protect against heart attacks and strokes.
- Previous studies on vitamin D supplementation and heart disease prevention have been inconclusive.
- Researchers in the new trial say increasing doses of vitamin D could improve heart health outcomes in future studies.
Low vitamin D levels affect nearly 42% of the adult population in the United States and are considered a potential risk factor for heart disease.
Research on vitamin D supplementation to prevent
Two new studies recently presented at the American Heart Association
The results suggest that current dosage recommendations should be revised to help people achieve their optimal vitamin D levels.
The studies are part of TARGET-D, a randomized clinical trial being conducted at Intermountain Health in Salt Lake City, UT. According to the researchers, people enrolled in earlier trials were not taking high enough doses of vitamin D, which could have led to inaccurate results.
“Our results show that simply giving patients a little vitamin D does not help them reach optimal levels,” lead author Heidi May, PhD, an epidemiologist at Intermountain Health, said in a press release.
“If researchers want to further study vitamin D dosing as a possible way to improve heart health, patients need to receive the right doses to achieve these ideal levels.”
In both studies, researchers assessed whether achieving optimal vitamin D levels through personalized supplement management could reduce the risk of cardiac events.
They found that to achieve ideal levels, patients needed to be given more than the daily recommended dietary allowance (RDA) of 600 to 800 international units (IU) of vitamin D.
“Our research group has performed numerous observational studies evaluating the association of vitamin D with adverse cardiovascular outcomes,” May told Healthline. “Based on previous observational studies, we were not at all surprised that participants’ levels were so low and that so many of them were supplemented at higher doses than what generally thought necessary.”
May explained that lower levels of vitamin D were associated with an increase in cardiac events “in steps.”
“Because of this stepwise association, we assessed at which level the risk no longer increased,” she said.
May noted that the current recommendation for vitamin D levels for bones and overall health is 20 nanograms per milliliter (ng/mL), which she said may be insufficient to reduce cardiovascular problems.
“Our observational data suggest that a level > 40 ng/mL is optimal for preventing cardiovascular events. However, given that TARGET-D is a randomized clinical trial and not an observational study, TARGET-D should be able to tell us whether reaching a level >40 ng/mL prevents cardiovascular events,” a- she declared.
In total, 632 patients were divided into two groups:
- 316 people received a recommendation to discuss their vitamin D treatment with their clinician
- 316 people received targeted vitamin D treatment
Among treatment participants, nearly 90% required vitamin D dosing, with 86.5% requiring more than 2,000 IU per day and 14.6% requiring more than 10,000 IU per day.
At three months, less than 65% of subjects reached the threshold of 40 ng/mL. Another quarter of subjects needed six months or more of vitamin D supplementation.
In the second study, researchers looked at whether participants had a cardiovascular event within 30 days of enrolling. This study is ongoing and will continue until 104 patients experience another cardiac event or die due to heart disease.
“These two studies showed that generally recommended levels of vitamin D supplement are not sufficient to increase vitamin D levels to a level considered beneficial,” said Dr. Cheng-Han Chen, board-certified interventional cardiologist and medical director. of the Structural Heart Program at MemorialCare Saddleback Medical Center in Laguna Hills, California. Chen was not involved in the studies.
“For this reason, it may be necessary for us to rigorously monitor blood levels of vitamin D in future clinical trials investigating vitamin D supplementation for cardiovascular health,” Cheng added.
Vitamin D deficiency is considered a risk factor for heart disease, but previous research investigating whether vitamin D treatment may provide a protective benefit has been inconclusive.
“Previous observational studies have noted an association between low vitamin D levels and increased risk of cardiovascular events such as heart attack or stroke. However, the reasons for this association are unclear,” Cheng said.
“It is hypothesized that vitamin D receptors present in cells of the vascular system are involved in inflammation of blood vessels, which could promote heart disease. »
Dr. Robert Segal, founder of Manhattan Cardiology, Medical Offices of Manhattan and co-founder of LabFinder, agreed that the relationship between vitamin D and heart disease is complicated and not fully understood. Segal was not involved in the new research.
“There may be a link between insufficient vitamin D intake and a higher risk of heart disease, but the evidence is not always strong and more research is needed to prove a clear cause-and-effect link,” a- he told Healthline.
“Vitamin D helps control blood pressure, inflammation and the function of the endothelium (the walls of blood vessels). A deficiency can worsen conditions like high blood pressure and cholesterol, both of which increase the risk of heart disease.
Segal explained that unhealthy cholesterol levels and insulin resistance are also associated with low vitamin D levels, which can contribute to heart disease.
Vitamin D supplements may be an option for people with low vitamin D levels, regardless of their health, but always check with your doctor first.
“We generally recommend that all patients with vitamin D deficiency take a supplement, not just patients at higher risk of heart attack or stroke,” Cheng said.
Segal explained that a healthcare professional can assess your unique needs and make vitamin D supplementation suggestions based on your health and lifestyle.
“Supplement choices should be based on each person’s unique situation, which may include their food, the amount of sunlight they receive, and their health status,” he noted.
“Self-prescribing large amounts of vitamin D without medical advice is not a good idea because too much or too little can be harmful. Hypercalcemia (high levels of calcium in the blood), which can occur if you consume too much vitamin D, can harm the heart and other organs,” Segal warned.
New research recently presented at the AHA Scientific Sessions suggests that current dosing recommendations and goals for vitamin D are insufficient.
Researchers say this could explain why results from previous trials involving vitamin D supplementation to prevent cardiac events were inconclusive.
Although the exact relationship between vitamin D and heart health is not yet fully known, it may be helpful to take a vitamin D supplement if your levels are low.
Talk to your doctor about your current vitamin D intake and whether you would benefit from additional treatment.