Calcium will Kill Me?

Apr 15, 2013

By Trevor Shewfelt, Pharmacist at the Dauphin Clinic Pharmacy


My son Eric came to me at breakfast and said, Dad, heres something. For your article you should write about why our dog Sheldon barks at our neighbors garbage bags. I was going to tell Eric that Sheldon barked because they are black and must look like a big dog to him. But everyones garbage bags and bins are black. Sheldon only barks at this one neighbors bin and bags. Then I was going to say it was because the bin and bags are close to our house, so Sheldon is just protecting his territory. But that doesnt make sense, because this neighbor isnt our immediate next door neighbor. They are a few houses down. Sheldon passes a few garbage bins before barking at this one. Finally I have to admit Eric has a good question that I have no answer for him. It is like the question, Are my calcium supplements going to kill me?


This question seems to have been popping in and out of the news over the last couple of years.


So what do we know? One study by Bolland et al in the British Medical Journal in 2008 looked at a large group of women with an average age of 74 and their calcium intake. The problem is this study wasnt designed to look for heart problems. Bollands group looked at the results after the fact to draw some conclusions. Bolland found an increase in heart attacks. This should be scary, right? Well the problem is the results werent statistically significant. That means we dont know if the calcium group really had more heart attacks than the control group or if it was just a random fluke.


A large German study published by Li et al in Heart in 2012 followed over 25,000 people with an average age of 50 for about 11 years. It found people who used calcium supplements were almost twice as likely as those who didnt to have a heart attack. The good things about this study were that it was designed to look for heart attacks, it wasnt just looking back on someone elses data and it was very large. The bad things were it really only asked people about their food and calcium intake once at the beginning of the study. They dont really know what food or calcium the patients consumed during the 11 years.


United States Preventative Services Task Force (USPSTF) now says that taking 400 IU of vitamin D per day and up to 1000 mg of calcium per day may not prevent broken bones in postmenopausal women. So, should we abandon calcium supplements altogether? In my opinion, no. Lets look at the reasons.


First, when it comes to stopping people from breaking bones, you have to look more carefully at the USPSTF recommendations. Most guidelines suggest higher calcium and vitamin D intakes than those the USPSTF said were ineffective for preventing fractures in postmenopausal women. The Institute of Medicine and Health Canada both recommend 1000 mg of calcium per day for women up to age 50, and 1200 mg per day for women over 50. Canadian osteoporosis guidelines recommend 1200 mg per day for people over 50 years of age. The USPSTF recommendations do not apply to people with established osteoporosis, vitamin D deficiency, or people in nursing homes. So the USPSTF recommendations may only mean that less than 1000 mg of calcium per day might not be enough calcium to stop broken bones.

The story gets a little murkier with calcium and heart attacks. If we believe a meta-analysis by Bolland et al in a 2010 British Medical Journal article then for every 1000 older adults who take calcium as a supplement for five years, there will be 26 fewer fractures at the expense of 13 more deaths, 10 more strokes, and 14 more heart attacks. That sounds like a lot of risk for the relatively small benefit. But the science still seems to be evolving and the evidence that calcium supplements cause heart attacks is still controversial. It is definitely not is the same realm as things like smoking and obesity and inactivity causing heart attacks. I would first worry about quitting smoking, getting 5 serving of vegetables into my diet per day and walking 30 minutes a day before I would stop my calcium supplements.

On the one hand the question of, Will my calcium supplements kill me? is similar to Why does Sheldon bark at one specific neighbors garbage bags and bin? The answer to both is I dont know. However when it comes to preventing heart attacks, I would suggest letting the researchers determine if the calcium effect is real or not and not worry about it too much. In the meantime focus on 0 cigarettes, 5 vegetables per day and 30 minutes of exercise per day to prevent heart attacks.


As always if you have any questions or concerns about these or other products, ask your pharmacist.


The information in this article is intended as a helpful guide only. It is not intended to be used as a substitute for professional advice. If you have any questions about your medications and what is right for you see your doctor, pharmacist or other health care professional.

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