Vitamin D Linked to Lower Risk of Suicide Attempts, Self-Harm

Feb 1, 2023 – The use of vitamin D supplements may reduce the risk of suicide attempts and self-harm in U.S. veterans, a new study says. 

In particular, Black veterans and those with low blood levels of vitamin D had the most significant response to the supplements.

“Vitamin D plays an important role in multiple systems – your bone health, skin, immune function, neurotransmission, and prevention of calcium buildup – so it’s important to look at the effects it can have,” says study co-author Jill Lavigne, PhD, a researcher with the Veterans Affairs’ Center of Excellence for Suicide Prevention and a professor of pharmacy practice and administration at St. John Fisher College in Rochester, NY.

Previous studies have found that people with low vitamin D levels have more severe depression and suicide-related behavior. Also, studies have found that vitamin deficiency is common in the U.S. military, especially in men and service members of color. 

Given that service members and veterans also have elevated suicide attempts, Lavigne and colleague Jason Gibbons, PhD, a health economist and postdoctoral fellow at the Johns Hopkins Bloomberg School of Public Health, tested the links between vitamin D supplement use, blood levels, suicide attempts, and intentional self-harm.

“We were surprised by the strength of the effect,” Lavigne says. “We’re very interested in what this could mean for different populations and how to help people better manage their risks.”

Lavigne and Gibbons studied 1.3 million U.S. veterans who did or didn’t receive vitamin D supplements from 2010 to 2018. About 490,885 veterans who received vitamin D₃ and 169,241 veterans who received vitamin D₂ were compared to veterans of similar demographics and medical histories who didn’t receive supplements.

Overall, vitamin D₃ use was linked to a 45% lower risk of suicide attempts and self-harm, and vitamin D₂ was linked to a 48% lower risk. 

Among the vitamin D₃ group, 1,786 veterans (0.36%) not on supplements had a suicide attempt or instance of intentional self-harm, compared with 991 veterans (0.2%) with supplementation. Similarly, among the vitamin D₂ group, 878 veterans (0.52%) without supplements had a suicide attempt or intentional self-harm, compared to 452 veterans (0.27%) with supplementation.

Veterans who had the lowest levels of vitamin D in their blood before supplements had a 64% lower risk when taking vitamin D₃. In addition, Black veterans had a 64% lower risk when taking vitamin D₃ and 58% lower risk when taking vitamin D₂. 

In general, for vitamin D_3, higher doses were linked to higher reductions in self-harm and suicide attempts.

“The effects were large,” Gibbons says. “As previous work has shown, those with more severe depression stood to benefit the most.”

Although more studies are needed to find the reasons why vitamin D appears to reduce the risk of suicide and self-harm, people should consider asking their doctor to test their vitamin D levels if they have concerns, he says.

“Typically, doctors only screen for vitamin D levels if a patient has a condition currently associated with low vitamin D,” Gibbons says. “This brings up the idea that we need to be screening more regularly for those who might have an indication for depression, anxiety, or self-harm.”

Lavigne and Gibbons are interested in other things related to the use of vitamin D supplements, such as drug interactions, nutrient absorption, recommended doses, and different blood levels. For example, supplements may not dramatically reduce self-harm risks once someone has sufficient vitamin D levels.

“This highlights the question of how we define insufficiency and deficiency,” Lavigne says. “This type of research can contribute to public health approaches to improve health.”

Lavigne suggests talking to a doctor about the best dose to take, as it’s possible to take too much. Vitamin D is a fat-soluble vitamin, she says, which means it’s retained by the body and not flushed out like water-soluble vitamins. The U.S. recommended dietary allowance for most adults is 600 units per day, although that may vary by person.

Also, since dietary supplements don’t need to be approved by the FDA before being sold, it’s important to look for high-quality brands and ingredients, she says. For instance, U.S. Pharmacopeia (USP), an independent, scientific nonprofit organization, has created a Verified Products Listing for more than 100 supplements across numerous retailers.

“There are a wide variety of supplements out there,” Lavigne says. “One of the things you can look for is the U.S. Pharmacopeia label, which means it has been tested for quality.”