Calcium Supplements Linked to Significantly Increased Heart Attack Risk
Before you panic, read my blog…..
When a headline like this comes across the newswire, my job becomes unnecessarily difficult. As a specialist in medical nutrition therapy and the author of several best- selling nutrition/health books regarding metabolism, diabetes, obesity… I face these dramatic reports on a daily basis. Unfortunately, people don’t have the time, expertise, or desire to read the studies or interpret them, and they take the headlines at face value. NOT SO FAST WITH THIS ONE.
The headline here is going to cause a stir because so many people supplement their diet with calcium. The reason for the supplementation is valid. According to the NIH, only about 30% of calcium contained in food is actually absorbed. Although you may calculate your daily dietary calcium intake to equal 1000mg/day from food, that amounts to only 330mg/day that is actually absorbed. The RDA for calcium varies based on age and gender, but…for the people in this study (ages 35 and 64) the RDA for calcium is: 1000-1200mg/day. If a person were to ingest 1000mg of calcium from food/day…and trust me, that is a high dietary calcium intake…they would still be 670mg-870mg short of the RDA for calcium!
So a headline that screams that calcium supplementation is linked to significantly increased heart attack risk…well….it calls for a very close look. I decided the best way to rebuttal would be to take verbatim statements from the press release and answer them on a point by point basis. My answer is in the highlighted message after the statements.
Statement #1 …”Those whose diets included a moderate amount (820 mg daily) of calcium from all sources, including supplements, had a 31% lower risk of having a heart attack than those in the bottom 25% of calcium intake.” So, when dietary intake and supplements were at about 820mg/day….there was a very significant decrease in the risk of heart attack
Statement #2 “But those with an intake of more than 1100 mg daily did not have a significantly lower risk.” : This is a direct contradiction to statement number #1 that states that those whose diet and supplements totaled 820mg/day have a 31% lower risk of heart attack. Are we to believe that if these people drank a glass of milk and had some cheese and their calcium intake reached 1100mg/day that their lowered heart attack risk (that occurred at 820mg/day) would disappear?
Statement #3 “There was no evidence that any level of calcium intake either protected against or increased the risk of stroke, which backs up the findings of other research, say the authors.” The discussion is about heart attacks, not strokes. “Apples to apples” is best when discussing the results of a research study
Statement #4 “ When the analysis looked at vitamin/mineral supplements, it found that those who took calcium supplements regularly were 86% more likely to have a heart attack than those who didn’t use any supplements.” Absolute contradiction to Statement #1
Statement #4 “And this risk increased further among those who used only calcium supplements. They were more than twice as likely to have a heart attack as those who didn’t take any supplements “ So, the only thing people did differently in their lives was take calcium supplements alone and this solo calcium supplementation made them twice as likely to have a heart attack???? I wonder how they extrapolated this?
Statement #5 They also suggest that many women taking calcium supplements to ward off brittle bones are already healthier than those who don’t, and that the overall protective effect is modest—in the order of just 10%. This is quite a contradictory statement …how could women who take calcium supplements be considered “already healthier” than those who don’t when according to this study, their risk of heart attack is significantly increased due to their calcium supplementation.
Statement #6 The evidence that dietary calcium is helpful while calcium supplements are not can be explained by the fact that dietary calcium is taken in small amounts, spread throughout the day, so is absorbed slowly, they say. Calcium supplements are meant to be taken in split doses, as the body can’t effectively absorb more than 600mg of calcium at once . Don’t forget that only about 30% of the calcium contained in food is actually absorbed. Without supplementation, it would be extremely difficult for the average man or woman to reach the requirement via food sources alone….
Supplements, on the other hand, cause calcium levels in the blood to soar above the normal range, and it is this flooding effect which might ultimately be harmful, they suggest. : Calcium is the only element/mineral that has its own regulatory system. Calcium levels in the blood are regulated on a moment to moment basis by the parathyroid glands. This is all the parathyroids do…they regulate the serum calcium level within a very narrow range so that the nervous and muscular systems can function properly. If calcium levels were to “soar” after taking a supplement (dramatic, yes?), the parathyroid stops making PTH. (Conversely, if serum calcium levels drop, the parathyroid produces PTH that removes calcium stores from bones/teeth.
I hope this explanation of the dramatic headline has helped to answer the questions you might be having about taking calcium supplements. At least realize that the report of this study do not confirm that calcium supplements increase the risk for heart attacks. And, in actuality, appear to be beneficial regarding decreasing the occurrence.
As always, consult with your MD regarding your medical condition.