Q: I have read conflicting information about the effects of vitamin D and calcium supplements on heart health. What’s the status?
A: In the body, calcium and vitamin D work together to build and maintain healthy bones. Many adults (especially women) take these two nutrients in supplement form, hoping to stave off osteoporosis, the bone-weakening disease that leaves older people prone to fractures. But how do these supplements affect cardiovascular health?
The answer is a bit complicated. Here are the key points, with additional context and advice below:
- Some studies suggest that taking calcium supplements may raise heart disease risk, but others do not.
- Low blood levels of vitamin D have been linked to a higher heart disease risk. But taking vitamin D supplements does not appear to lower that risk.
- Some evidence hints that taking calcium and vitamin D together might slightly increase the risk of stroke. But the largest study to date found no increased stroke risk.
Make no mistake — the above findings refer only to supplements, not the food sources of these nutrients. There’s no evidence that calcium from food increases cardiovascular risk. In fact, observational studies suggest that people who consume higher amounts of dietary calcium tend to have lower rates of diabetes and heart disease. Calcium is also one of the key minerals involved in blood pressure control.
Studying the health effects of calcium supplements has been complicated, in part because so many people take them. Also, osteoporosis and heart disease have shared risk factors, including a lack of exercise and an unhealthy diet. So people who take calcium to prevent or treat osteoporosis may also be more likely to heart disease.
In theory, calcium supplements may quickly raise blood calcium levels. This excess calcium might be more likely to be deposited in the heart’s arteries, thereby raising the risk of a heart attack. However, the scientific evidence doesn’t support that idea.
It’s always best to get your nutrients from foods rather than pills. Try to get most of your calcium and vitamin D from your diet. If you aren’t meeting the Recommended Dietary Allowance from the food you eat, you can fill any gaps with a supplement. This is especially important for postmenopausal women who have low bone density (osteopenia) or osteoporosis. But don’t assume that “more is better,” as too much of these nutrients might actually be harmful.
(Howard LeWine, M.D., is an internist at Brigham and Women’s Hospital in Boston and assistant professor at Harvard Medical School. For additional consumer health information, please visit www.health.harvard.edu.)