There has been a lot of talk recently some very confusing research published in the literature about calcium supplements and heart disease risk. Some studies seem to show that increased calcium intake protects against heart attacks, and some seem to show an increased risk. So what’s the right answer?
Does calcium cause heart disease?
First of all let’s talk about why people (especially women) take calcium supplements in the first place. Calcium supplements are recommended in women to prevent the bone loss that leads to osteoporosis.
Women start to lose bone mass at about age 30 and it really accelerates after menopause. 50% of women over 50 will have an osteoporotic fracture. Hip fracture is a leading cause for women to wind up in a nursing home, and 50% of women who suffer a hip fracture will die within 1 year. Preventing osteoporotic fractures is a big deal.
Does it make any sense that taking extra calcium would be dangerous? Well let’s think about that. Calcium is required for life. Calcium is required for proper function of the heart, blood vessels, muscles and nervous system. The blood level of calcium is VERY tightly regulated. In fact, one of the reasons osteoporosis happens is that the body is willing to sacrifice bone strength to maintain that blood level of calcium.
What happens when you take calcium? First of all the digestive system can only absorb about 500 mg of calcium at one time, so if you take more than that it just goes out in the stool. Calcium is absorbed and goes into the bloodstream where some of it is taken up by the cells if they need it. Some of it is put into the bone if there is new bone being built (this is complicated but requires bone-building cells called osteoblasts in addition to magnesium, vitamin D and other trace minerals). Anything the body doesn’t need gets released into the urine and excreted.
If you don’t get enough calcium in your diet, the body goes to the bank. The bank is, of course, the skeleton. The blood level of calcium must be maintained to keep the nervous system and circulatory system working right. So if you don’t get enough calcium in your diet, over time calcium is released from the bones and the bones get weaker.
Why do some researchers think calcium causes heart disease? There have been studies published in the last 5 years that were designed to look at calcium intake and osteoporosis risk. When the researchers went back and reanalyzed the results, sometimes the cohorts with a high calcium intake have a higher number of heart attacks. Sometimes they have a lower number. Sometimes they have more in men but fewer in women. It’s all very confusing. The thing to remember though is that these studies were NOT designed to look at heart attack risk, they were designed to look at osteoporosis risk, and it’s dangerous to make firm conclusions about associations found in ad hoc analysis.
There WAS, however, a study published this year that WAS designed to look at calcium intake and heart attack risk. Researchers followed almost 75,000 women for 24 years and found that women who took >1000 mg of calcium supplements per day had an 18% LOWER risk of cardiovascular disease (heart attack and stroke) and a 29% LOWER risk of heart attack than women who took no calcium supplements. The researchers did good statistical analysis and factored in age, body mass index, dietary calcium, vitamin D intake, and other CVD risk factors.
What does this all mean? The bottom line is that calcium supplements help prevent bone loss in women who don’t get all the calcium they need from their diet. While the research isn’t clear that calcium supplements prevent heart disease (although it is reassuring) it DEFINITELY doesn’t support the conclusion that calcium supplements CAUSE heart disease.
Which calcium supplement should you take? Taking calcium alone isn’t a good idea. After all, your bones need more than just calcium for strong mineral matrix. And calcium competes with magnesium in the digestive tract so taking calcium alone decreases magnesium absorption. As I wrote recently, most of us don’t get enough magnesium in our diets as it is! Vitamin D is also required, especially if you live in a northern climate where the winter sun isn’t strong enough to help your skin make vitamin D (like here in Cleveland).
The best calcium supplement for bone health has calcium, magnesium and vitamin D as well as trace minerals needed for strong bone matrix. As you know, I work with the Shaklee Corporation (you can look here for my reasons why) and Shaklee’s OsteoMatrix is a great choice. The caplets are small and easy to swallow (no enormous chalky horse pills!) and don’t cause constipation as some calcium supplements can do.
Be aware that OsteoMatrix contains vitamin K (also needed for bone health) and may not be a good choice for those who take Coumadin to thin the blood. Shaklee’s Chewable Cal Mag Plus is better – calcium, magnesium, vitamin D and trace minerals but no vitamin K. And they make a great antacid for those with occasional heartburn!
Calcium is required for life. Your body will steal it from your bones to keep your heart, muscles and nervous system working right. If you’re not getting enough from your diet you should definitely consider supplementing. It’s good for your bones and NOT dangerous for your heart. That’s the bottom line.
QUESTION: Have you been told by your doctor to take extra calcium? Have you been told by your doctor to AVOID taking calcium supplements?