You’re probably reading this because you heard that calcium supplements may increase the risk of a heart attack. Because of this let's review the evidence and give you some information to help.
What kind of Calcium Study Was This?
The study people are talking about was published in the British Medical Journal. This investigation was actually a compilation of previous studies on calcium and looked at heart attack and other outcomes from 11 different calcium clinical trials which all totaled included, 12,000 people. In each study, people received more than 500 mg of calcium a day.
These facts are important because the results may not hold true for those who take less than 500 mg of calcium a day. All studies used calcium only.
In other words, none of these were studies of calcium and vitamin D.
Also, this study did not directly investigate calcium and heart attacks; rather, the researchers asked those who did previous calcium studies about the side effects they observed. This is important to remember.
Do Calcium Supplements Cause Heart Attacks?
The study found that calcium supplements resulted in a 31% increased chance of a heart attack compared to those who did not take calcium supplements. Calcium was also associated with a non-significant increased risk for stroke and overall death. Non-significant means it wasn't “statistically significant.” It doesn't mean you shouldn't pay attention to it because it's definitely “significant” if it happens to you.
The risk of a heart attacks seemed to be greatest when people already were getting over 800 mg of calcium from their foods. This was seen in both men and women.
This study is actually a follow-up to another investigation published in 2008 in the British Medical Journal which also found more heart attacks in those who took calcium supplements. This other study involved 1471 older women (average age 74) who were followed for 5 years.
What Type Of Calcium Causes Heart Attacks?
This study noted that it didn’t seem to matter which type of calcium (calcium carbonate, calcium citrate, etc) people took. All types appeared to increase heart attacks.
Do Calcium Foods Cause Heart Attacks?
No. This study does not show that calcium from food causes heart attacks. On the contrary, several studies show that calcium eaten from food seems to decrease
How Do Calcium Supplements Cause Heart Attacks?
While this study did not offer any explanation of how calcium supplements might increase heart attacks, one theory put forth was that calcium increases the hardness (calcification) of blood vessels in a similar way as it increases the hardness of bones. Regardless of theories, more research needs to be done before scientists know how calcium supplements might do this.
My Thoughts About This Study
Let me try to offer some help as you grapple with all of this stuff:
- Everybody is different so talk to your doctor before you stop taking your calcium supplements
- This study found more heart attacks in people who were already getting over 800 mg a day from food. If you eat a calcium-rich diet now, try to figure out how much you're getting from food. If you believe you need more, try increasing calcium from food before adding a calcium supplement. Food calcium has never been shown to cause heart attacks.
- Most who take calcium supplements don’t know that the best research on the bone-building effects of calcium comes from looking at people who get their calcium from foods. In other words, calcium supplements don’t seem to be as good at building bones as calcium-rich foods.