In 2010, a study published in British Medical Journal concluded that women taking calcium supplements significantly increased their risk of heart disease — by as much as 27%.
The authors’ conclusions were picked up by mainstream media and sensational headlines blanketed the airways and print media. The negative headlines made their impact as they fearfully convinced women to stop taking their calcium supplements.
What a mistake. The limitations and flaws of the study driving the negative headlines were numerous, prompting Life Extension® to publish a full rebuttal.
Here are three of the flaws worth noting:
• The authors excluded people taking vitamin D and magnesium. This means that study subjects (who the mainstream claims suffered higher heart attack rates due to calcium) would have been seriously deficient in vitamin D and magnesium — two essential nutrients that protect against heart attack.
• The doctors who compiled this analysis also conveniently omitted major clinical trials showing that those with higher calcium intake had significantly lower cardiovascular rates.
• Vitamin K2 levels were never assessed. If subjects are low in K2, calcium will deposit in tissues other than bone.
Despite our efforts to clear the air over the past few years, many women have continued to question whether or not they should take calcium supplements. A number of them have actually read our rebuttal, but still want more assurance that taking calcium is safe.
Well, here's the evidence you've been waiting for, published in the prestigious medical journal Osteoporosis International.
Calcium Supplements Don’t Increase Heart Disease Risk
Straight from the author’s mouth: “In a prospective cohort study of 74,245 women in the Nurses' Health Study with 24 years of follow-up, we found no independent associations between supplemental calcium intake and risk of incident coronary heart disease (CHD) and stroke.”1
Is the case closed? No. With science, the case is never closed. But this is one big, strong nail in the coffin of the hypothesis that calcium supplements increase heart disease risk. So let’s break it down.
First, this is a prospective cohort study. This means that researchers follow a group of similar individuals (the cohort) who differ with respect to certain factors under study, to determine how these factors affect rates of a certain outcome.
For example, one might follow a cohort of middle-aged truck drivers who vary in terms of smoking habits, to test the hypothesis that the 20-year incidence rate of lung cancer will be highest among heavy smokers, followed by moderate smokers, and then nonsmokers. In our case, the cohort is aging women using varying amounts (or none) of calcium supplements.
The outcomes under investigation are coronary heart disease and stroke. Next, is the large size of the cohort — over 74,000 — and the larger the cohort, the more credible the conclusions.
And lastly, is the follow up period — every four years over a 24-year follow-up period. It’s important to assess the tested factor (in this case calcium supplementation) more frequently than not.
In some cohort studies, researchers only check at the beginning and at the end of the total study time. This is not a reliable way to analyze data and draw conclusions. But in this case, the researchers assessed calcium supplementation every four years. That makes the data more reliable — meaning we can place more confidence in the report of calcium supplementation by the subjects.
What You Need to Know About Calcium Supplements
Calcium supplements, along with vitamins D, K2 and magnesium, continue to help women protect their bones without increasing the risk of heart disease.
In my opinion, if you’re currently supplementing with calcium you should continue to do so, and if you currently aren't, consider speaking with your physician about adding it to your supplement regimen.
1. Osteoporos Int. 2014 May 7. [Epub ahead of print]