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 in July 2010. This study was actually a compilation of other studies on calcium and looked at heart attack and other outcomes from 11 different calcium studies which all totaled included 12,000 people. In each study, people received more than 500 mg 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.
Does Calcium 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 not 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. To 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 I want you to talk to your doctor before you stop taking your calcium supplements.
- This is study found more heart attacks in people who were already getting over 800 mg a day from food. This is almost the RDA for calcium for most people. If you eat a calcium rich diet now, try to figure out how much your getting from food. If you deem that you need more, try increasing calcium from food before adding a calcium supplement. Food calcium has never been shown to cause heart attacks.
- Most people 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.
- Remember that right now there are not many studies that specifically investigate whether calcium causes heart attacks. While it does appear to be well done, it does have its limitations and future research may not find the same thing.
- While people debate whether calcium causes heart attacks, my best advice is eat more calcium-rich foods if you can and speak to your doctor or dietitian about whether you need a calcium supplement. Dietitians in particular, are very knowledgeable on this topic and can give you the most up to date information.
- If this study holds true, it reinforces what I've been saying for years – that all supplements have side effects if you use too much of them.
- Most women who take calcium do so because of osteoporosis. But, calcium supplements or calcium from foods are not enough. lifting weights is also needed. The problem is that most women who lift weights do it the wrong way.
Just remember, food first – supplements second – and you'll be OK.
What do you think?