Before I begin my usual reporting on published studies, I want to thank those of you who emailed or wrote to me with condolences on the death of my father. A friend who attended his funeral felt that I had omitted one of his most salient traits in the short eulogy I posted last week. My father was a true feminist. He had two daughters and felt that they could choose any career that they wanted, even in the then male – dominated fields of math and science. A generation (or 2) later we are still encouraging gender equality in these fields while it also appears (I have to add this) that our reproductive rights have been brought into question. So thank you Daddy…. your push for science education paid off…even if (in his world of theoretic physics) it led to “just” medicine. I will always be grateful.
Now onto the question of calcium supplementation: As soon as the article published in the British Medical Journal Heart was brought to everyone’s attention by the media, patients called my office asking “Should I continue to take my calcium supplements?”
The article was based on a prospective study of approximately 24,000 men and women in Germany who were between the ages of 35 and 64. The participants answered questions about their diet, dietary calcium and use of supplements and/or calcium only supplements during the 11-year study period. The brands and quantities of supplements were not identified. A self-administered questionnaire was used to assess consumption of 148 food items. From the latter, the amount of dietary calcium intake was calculated. And, of course, dairy foods were the main sources of dietary calcium. The participants were also asked if they had taken vitamin/mineral supplements in the last 4 weeks prior to the survey or if they took calcium only. They were then divided in four groups (or quartiles) depending on dietary calcium intake (high or low), use of multiple supplements or calcium only.
The authors reported that total dairy or non dairy calcium intake did not have a statistically significant association with cardiovascular risk except for a “likely” reduction of heart attack associated with a higher dairy calcium intake. But the study also suggested that heart attack risk might be “substantially” increased by calcium supplements. Those who took only calcium supplements were, in their calculations twice as like to suffer heart attacks as those who didn’t take any calcium supplements.
They also stated that a higher calcium intake was associated with favorable factors, including younger age, higher likelihood of having a university degree and being physically active, less likelihood of being overweight or obese, an average shorter time of having smoked and lower lifetime alcohol consumption. Compared with non-users, users of calcium supplements were more likely to be women, physically more active and less likely to be overweight/ obese. However, users of calcium supplements were older, had an overall lower educational level and a longer duration of smoking. (So this means that they had additional factors that could contribute to heart attacks.) There was one more issue that I found concerning when I read the article; and that had to do with the actual low number of participants who took the calcium- only supplements; just 3.6% of all the study participants. Moreover there was no indication of dose or type of calcium supplements that were taken.
Having come to my own “this is not sufficient” conclusion while reading the article, I also agree with the official one offered by the president of the National Osteoporosis Foundation (NOF): “While the benefit’s of calcium to bone health are well documented, this study’s findings are inconclusive.” The organization feels that more research is needed to better understand the potential relationship between calcium supplements and heart attack and that individuals should continue to meet their daily calcium needs from food sources first, and not (based on this article), discontinue calcium supplements.
Remember, everyday we “use up” calcium through our body’s metabolism, excretion (urine and feces) and sweating. In order to keep the calcium level stable in our blood and tissues, we either have to intake what is lost or get it from our internal calcium storage… our bones. Based on a huge amount of clinical data the current NOF recommendation for daily calcium intake is 1,000 mg daily for women under age 50 and 1200 mg for women over the age of 50.
There is no doubt that that best way to get your calcium (or any of the other vitamins and minerals on the food and pharmacy shelves) is though nutrition. The food with the most calcium will be dairy-based. So go for that milk, yogurt and cheese but make sure it’s low or non-fat. You can also get calcium in fortified juices and soy milk. Finally, don’t forget the green vegetables such as kale, broccoli and spinach. If you want to figure out how much you are getting in your packaged products just look at the table of nutrition facts….it will tell you the percentage of calcium in a portion. Know that this is calculated from a daily requirement of 1000mg. (Somehow the manufacturers forgot that many of us are over 50 and need more.) So 30 % will mean 300 mg. Just spend a day or two figuring out what you usually eat and how much calcium you are getting. That’s what I do. If at the end of the day I didn’t have that yogurt or milk (in my latte) I add it on at night or the next morning. And remember, we can’t absorb more than 600 mg at a time with most of the supplements (slow release may be the exception)….so don’t try to get it all at once.
We don’t have to become stooped, little old ladies who are in pain, or immobilized. And although calcium and vitamin D are not going to reverse osteoporosis, sufficient amounts will help prevent bone loss.