- New research found that vitamin D, when taken with calcium, may lower blood pressure in obese older adults.
- The study lacked a placebo group, which makes it hard to tell whether vitamin D is actually responsible for lowering blood pressure.
- There’s currently not enough evidence to suggest vitamin D can benefit heart health, but experts say it’s still important to meet the daily recommended dose of vitamin D.
Taking vitamin D and calcium supplements could help lower blood pressure in older adults with obesity, according to new research.
The study, published on Nov. 12 in the Journal of the Endocrine Society, investigated how varying doses of vitamin D might affect the health of 221 overweight seniors living near Beirut, Lebanon.1
“Vitamin D supplementation—when co-administered with calcium—may decrease blood pressure in overweight elderly individuals,” lead author Ghada El-Hajj Fuleihan, MD, MPH, professor of medicine at the American University of Beirut, told Health. “Obese individuals, individuals with hypertension, and those with low vitamin D levels may benefit the most.”
Almost one in five older American adults is
vitamin D deficient, meaning they fail to meet the daily recommended dose of 600 to 800 IUs of vitamin D.
This is not the first study to investigate the connection between vitamin D levels and heart health—past research has flagged vitamin D deficiency as an “independent risk factor for high blood pressure.” However, studies on the subject have been inconclusive, and it’s not clear whether vitamin D supplements can actually be used to treat or prevent high blood pressure.4
The same is true for this latest study, said
JoAnn Manson, MD, MPH, DrPH, professor of medicine at Harvard Medical School and chief of Preventive Medicine at Brigham and Women’s Hospital. The lack of a placebo group in this new research makes it difficult to determine whether the observed reduction in blood pressure is actually caused by vitamin D supplements, she explained.
“The higher [vitamin D] dose did not confer greater benefits for blood pressure reduction than the lower dose,” Manson told Health.
For this study, researchers were originally interested in seeing how calcium and vitamin D supplementation might affect bone density and insulin resistance.
They recruited 221 participants who were at least 65 years old and had a body mass index (BMI) over 25, meaning they were considered
overweight. They also had vitamin D blood levels between 10 and 30 ng/mL (levels below 20 ng/mL are considered deficient).
2
Participants were randomly split into two groups. Both received 1000 mg of a daily calcium supplement, but one group received a small dose of vitamin D (600 IU) while the other received a larger dose (3,750 IU).
The researchers took participants’ health measurements at six months and one year, and noticed that blood pressure measurements changed slightly over the course of the study.1
Specifically, the high-dose group lowered their systolic blood pressure (the top number on a reading) by 4.2 mmHg, and the low-dose group reduced theirs by 2.8 mmHg. For diastolic blood pressure (the bottom number), participants in the high-dose group saw a reduction of 3.02 mmHg, and those in the low-dose group saw a 2.6 mmHg reduction.1
Taking a closer look at the data, the researchers noticed that only patients with
obesity—or those with a BMI of 30 or higher—saw significant blood pressure benefits from taking the supplements. In this subgroup, both doses of vitamin D lowered systolic blood pressure, and the high vitamin D dose lowered diastolic blood pressure.
1
People with obesity tend to have lower levels of vitamin D, Fuleihan said, which could explain why they benefitted most.
The study also found that the supplements lowered blood pressure in participants with hypertension, regardless of BMI or vitamin D group.1
Most of the researchers’ analyses revealed that higher doses of vitamin D didn’t lead to significantly different results as compared to the lower dose.
This is consistent with other research—doses beyond the daily recommendations don’t necessarily confer an extra health boost, said Manson. Once the body gets enough vitamin D, any additional vitamin D usually goes unused, in which case it can sometimes become toxic.
Though the study seemed to identify a positive link between taking supplements and improvements in blood pressure, it’s not clear if those benefits should actually be attributed to vitamin D.
“The results are not convincing,”
Michael Hall, MD, cardiologist and chair of the department of medicine at the University of Mississippi Medical Center, told
Health.
The study was originally designed to test whether calcium and vitamin D supplementation improved insulin resistance, not blood pressure, he noted. Since this wasn’t the main goal of the original study, this analysis is exploratory, and any results need to be verified in future studies.
Another key limitation, Hall and Manson said, was the lack of a true placebo group. Because all of the participants received calcium and vitamin D supplements, it’s hard to say whether vitamin D was actually responsible for lowering blood pressure. Some other factor could have been at play.
“After people enroll in a randomized trial, they may, for example, become more health conscious,” Manson said.
What We Know About Vitamin D and Heart Health
Several observational studies found that people with lower levels of vitamin D tend to be at a higher risk of heart attacks, stroke, heart failure, and death from heart disease.6 Plus, there’s some evidence that vitamin D deficiency may cause tissue changes that could raise the risk of cardiovascular issues.7
However, studies that assessed the evidence from multiple clinical trials haven’t found strong, consistent evidence that vitamin D supplementation benefits cardiovascular health or blood pressure.89
“We had done a meta-analysis of 21 trials looking at vitamin D different doses, whether it lowers risk of cardiovascular disease, heart attack,
stroke, cardiovascular death,” said Manson. “We [did] not find [a] single trial that shows reduction in cardiovascular event with vitamin D.”
Another study, published in October, tracked participants’ levels of two specific proteins that point to cardiac stress or injury. They found that vitamin D supplementation at any dose had no effect on these biomarkers over the course of two years.10
Though there does seem to be a link between vitamin D and heart health, it’s possible that other factors are driving that connection.
For example, people with poor heart health may get outdoors and exercise less often and may eat an unhealthy diet, which could explain their lower levels of vitamin D.
For people without any symptoms of vitamin D deficiency, a U.S. Preventative Services Task Force found no convincing evidence that screening or taking supplements can necessarily improve health outcomes.1213
“I think vitamin D supplements are certainly reasonable in people who are deficient in vitamin D, but would not recommend supplementation in people without vitamin D deficiency,” said Hall.
To ensure you’re getting the vitamin D you need, first start with sun exposure and diet, Manson and Hall recommended. Many foods are rich in vitamin D, including:2
But for those who still aren’t able to get enough vitamin D, Manson recommends starting with a small dose (1000 IU) of vitamin D daily for a few months.
Speak with your doctor if you’re considering taking vitamin D supplements, or you think you’re experiencing symptoms of deficiency, which could include weakness or bone and muscle pain.
https://www.health.com/vitamin-d-lower-blood-pressure-older-adults-obesity-8743016