Calcium Will Kill Me?
Apr 25, 2011
By Trevor Shewfelt, Pharmacist at the Dauphin Clinic Pharmacy
I hope everyone had a good easter. We had some different easter eggs this year. My parents spent the winter in Texas and came back with some special eggs for their grand kids. They are actual egg shells with a nice colorful paint job. On the inside, though, the eggs were filled with confetti. My mom said in Mexico and Texas the kids would break them over each others heads. So, after finding the eggs my children were encouraged to go outside and break confetti eggs on each others head. This whole egg-breaking confetti spilling thing was very surprising to me as my mother was always very neat when I was growing up.
The other surprising thing this week was the calcium phone call I got. A long time customer called on the phone. She said a girlfriend of hers was watching the news and it said taking calcium would cause heart attacks. Did I know anything about that? The answer was no, so I started looking into it.
So what do we know? There was a really big study done in 2002 called the Womens Health Initiative Study. Weve talked about it before in relation to hormone replacement. This time we are talking about calcium and vitamin D. The Womens Health Initiative (WHI) study also looked to see if calcium and vitamin D caused heart problems. When the WHI published its results, it said there was no evidence that calcium and vitamin D caused heart problems.
Another group led by Bolland, et. al, looked at the WHI numbers again. Bolland et. al. published a paper in the British Medical Journal that said the original WHI conclusions were wrong about the calcium. In the WHI calcium trial there were women taking calcium and vitamin D and women on a placebo. But Bolland didnt like that the WHI group let all the women use their own calcium plus vitamin d if they wanted. So that means some of the women on the placebo were actually taking calcium and vitamin D. So Bolland said the WHI trial really looked at women who were taking a large dose of calcium plus vitamin D versus those that were taking a small dose. Bolland says this masked the results.
So the Bolland group went back through the WHI study and tried to tease out women who were actually taking no calcium and match them up with women who were taking calcium. These women were 63 years old on average and Bolland looked at over 36,000 of them. The bottom line in this study was that if you treat 1000 women for 5 years with calcium and vitamin D you will prevent 3 fractures. But if you treat those same 1000 women for 5 years with calcium and vitamin D you would cause 6 heart attacks or strokes.
That sounds serious, doesnt it? No one wants to be one of those 6 women who got a heart attack or stroke. But remember the odds are low. It would take 1000 women taking calcium for 5 years to get those 6 heart attacks and strokes. Looking at the numbers another way, that is 1.2 heart attacks or strokes per 1000 woman years of calcium and vitamin D. If you want to look at things that are truly bad for heart attacks and strokes, look at smoking. In 1991 LaCroix et al published a study in the New England Journal of Medicine that said women between the ages of 65-69 died from heart attacks and strokes at a rate of 15.9 deaths per 1000 women years of smoking. That is nearly 8 times worse than the calcium. In a 1997 study in the International Journal of Epidemiology, Haapanen et al looked at women between the ages of 35-63 in Finland. The women who exercised the least got heart disease at a rate of 8.8 per 1000 woman years. This is about 4 times worse than the calcium reported effects.
The calcium study looked at some other odd things. Just like in the hormone version of the WHI, in the calcium arm, the women were 63 years old on average. That is at least 10 years later than we would normally put someone on calcium. The study authors said that women who were already on calcium didnt seem to have this increased risk of heart and stroke. So maybe this calcium effect just says we shouldnt start a woman in her mid-60s on calcium if she has never had it before.
The authors of the calcium study didnt find that the women died more often. This may seem like a minor point, because no one wants to get a heart attack or stroke. That is true, but if adding calcium was really that bad, why didnt more women in the calcium arm die of heart attacks and strokes than in the non-calcium arm?
Will my calcium pills kill me? The answer still is that we dont know. It is an important question for the scientists to look into, but I dont think anyone should throw out their calcium pills yet. If you are worried about your heart, do some things we know that will help. Get some exercise. Current guidelines say 150 minutes of exercise per week. That is 20-30 minutes of exercise per day. So lets get on those walking shoes and start that 10 minute walk in the morning and 10 minute walk at night. And the number one thing you can do to help your heart is to quit smoking.
British Medical Journal Article about calcium and heart attacks: http://www.bmj.com/content/342/bmj.d2040.full.pdf
NEJM article about smoking and older men and women : http://www.nejm.org/doi/full/10.1056/NEJM199106063242303
International Epidemiology article on exercise in older men and women: http://ije.oxfordjournals.org/content/26/4/739.full.pdf
As always if you have any questions or concerns about these or other products, ask your pharmacist.
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