Calcium Supplements

When Your Patients Ask About Calcium Supplements

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Americans spend more than $1 billion a year on calcium supplements in hopes of staving off osteoporosis. In fact, many of the older patients in your practice probably take calcium supplements to prevent bone loss and hip fractures. So it’s likely that they may have questions for you about a recent study showing that calcium supplements might increase the risk of heart attack and should be “taken with caution.”[1] The findings from the study also indicated that overall calcium intake from dietary sources, such as dairy products, conferred no significant advantage in terms of staving off heart disease and stroke.

The findings are based on results from almost 24,000 participants of one of the German arms of the European Prospective Investigation into Cancer and Nutrition (EPIC) study in Heidelberg. All the participants were between the ages of 35 and 64 when they joined the study between 1994 and 1998.

Normal diet for the preceding 12 months was assessed using food frequency questionnaires, and participants were quizzed about whether they regularly took vitamin or mineral supplements. Their health was tracked for an average of 11 years, during which time 354 heart attacks, 260 strokes, and 267 associated deaths occurred.

After taking account of factors likely to influence the results, those whose diets included a moderate amount (820 mg daily) of calcium from all sources, including supplements, were 31% less likely to have a heart attack than those in the lowest 25% of calcium intake.

But those with an intake of more than 1,100 mg daily from both food and supplements did not have a significantly lower risk of heart attack. 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.

When the analysis turned to vitamin/mineral supplements, it found that those who regularly took calcium supplements were 86% more likely to have a heart attack than those who didn’t use any supplements. People who took calcium supplements without any additional vitamins or minerals were twice as likely to have a heart attack as those who didn’t take any supplements. The researchers believe that supplements, unlike calcium from food (occurring naturally or fortified), cause calcium levels in the blood to soar above the normal range, and it is this flooding effect that might ultimately be harmful.

What Can You Tell Patients?

This study, which was reported in more than 1,000 media outlets around the world, had some important limitations. Users of calcium supplements were older and had a longer duration of smoking, which may have influenced the results. In addition, the study was not designed to assess the effect of calcium supplements on heart disease. And when taken in context, the number of heart attacks and strokes (611) was very small compared with the total number of people in the study (23,980). And there were no records as to how much calcium was present in the supplements.

This study really doesn’t provide enough clarity to help patients make a decision one way or the other. The most important data from the study, which was somewhat overshadowed in the media reports, was that according to various cardiologists and endocrinologists interviewed following the release of the study, the middle road is probably to eat a balanced diet and take a once-daily multivitamin. One of the key points in the study was not well reported by the media outlets: the risk of heart attack was the highest in people who took calcium supplements as a single supplement without other vitamins and minerals.

Calcium needs vary by age and gender. Adults generally need 1,000 mg daily, rising to 1,200 mg for women older than 50 and men older than 70, according to guidelines issued in 2010 by the Institute of Medicine (IOM).[2] The IOM has also established a safe upper limit of 2,000 mg/calcium/day for adults.

While some clinicians are cavalier about recommending a calcium supplement for their patients—and especially their older patients—there may be no need to do so. With calcium available in fortified foods such as cereal and juices and naturally occurring in dairy products, green leafy vegetables, tofu, and some seafood, it’s not that difficult for people to meet their calcium requirement. Just 6 oz of calcium-fortified orange juice (300 mg), a bowl of calcium-fortified cereal (400 mg-750 mg) with ½ cup milk (150 mg), and 5 oz of salmon for dinner (350 mg) will yield between 1,200 mg and 1,550 mg/day. Patients should be urged to consume reduced- or fat-free dairy products to encourage heart health. The best advice? Work with patients to determine their own personal calcium needs, based on how much calcium they consume per day and their risk of fall or broken bones. If patients are unable or unwilling to consume more calcium from food, you might recommend a multivitamin with calcium and vitamin D and encourage them to exercise and stop smoking. Click here for a comprehensive printable list of dairy and non-dairy calcium sources in food.

 

Jill Shuman, MS, ELS
Published July 10, 2012

 

References

  1. Li K, Kaaks R, Linseisen J, Rohrmann S. Associations of dietary calcium intake and calcium supplementation with myocardial infarction and stroke risk and overall cardiovascular mortality in the Heidelberg cohort of the European Prospective Investigation into Cancer and Nutrition study. Heart. 2012;98(12):920-925.
  2. Ross AC, Taylor CL, Yaktine, AL, et al. Dietary Reference Intakes for Calcium and Vitamin D. Washington DC: The National Academies Press; 2010.