Features August 2012 Issue

Dietary Calcium May be Healthier for the Heart than Supplements

Recent study suggests supplements may raise the risk of heart attack.

If you can get your daily calcium needs from dietary sources rather than supplements, you may be helping your heart in the process. A study published in the June issue of the journal Heart found that people who take calcium supplements face a higher risk of heart attack than those who don’t take calcium supplements.

In addition, researchers found a slight protective effect of dietary calcium, with study participants who had the highest dietary intake of calcium experiencing a lower risk of heart attack than those who consumed the least calcium from food sources each day. Researchers emphasized that this study, as well as others that have also suggested a higher heart risk associated with calcium supplements, should not be interpreted as a reason to stop taking calcium supplements. Such supplements are often recommended to older adults to combat age-related bone density loss.

Instead, researchers suggest that individuals look for ways to enhance their dietary intake of calcium as a means of ultimately reducing their need for supplements.

Registered dietitian Julia Zampano, RD, LD, with Cleveland Clinic’s Preventive Cardiology & Rehabilitation, says it’s perfectly reasonable to think you can get enough calcium in your diet to meet your body’s needs and help bolster bone strength.

“Men and women who are over 50 should get 1,200 mg of calcium per day,” she says. “Dairy sources include milk, natural and processed cheese, yogurt and ice cream. Non-dairy sources include broccoli, almonds, tofu, spinach and seafood, such as mackerel, salmon and shrimp.” (see chart)

Metabolizing Calcium
One of the reasons why dietary calcium may be healthier than calcium supplements is in the way the body metabolizes calcium from those two sources. In an editorial accompanying the study in Heart, University of Auckland, New Zealand researchers Ian Reid, MD, and Mark Bolland, PhD, suggest that taking supplements once or twice a day does not allow the body to process calcium in the same way it does getting calcium from food, especially if dietary calcium is consumed throughout the day.

They wrote, “Calcium supplements have been widely embraced by doctors and the public, on the grounds that they are a natural, and therefore, safe way of preventing osteoporotic fractures. It is now becoming apparent that taking this micronutrient in one or two daily boluses is not natural, in that it does not reproduce the same metabolic effects as calcium in food. We should return to seeing calcium as an important component of a balanced diet and not as a low-cost panacea to the universal problem of postmenopausal bone loss.”

Calcium supplements come in two forms: calcium citrate, which can be taken with or without food, and calcium carbonate, which should be taken with food. Generally, calcium supplements can be taken any time of day, though it’s generally recommended that you divide your daily total into two dosages.

But even by dividing up a calcium supplement, the concentrated amount of calcium entering the system with each dose can cause a spike in serum calcium, which is the fluid calcium in the bloodstream and tissues of the body, as opposed the calcium that comprises the skeleton. Researchers believe that one or two spikes in serum calcium due to supplements may help explain the heart attack risk associated with the supplements.

Dietary calcium is generally consumed in smaller doses and is often accompanied by fats and protein, which help it digest more slowly, without spiking your serum calcium levels.

“Basically dietary and supplement calcium are absorbed differently, depending on the environment of the gut and what you take it with,” Zampano says.

One other consideration is that some medications, such as bisphosphonates, antibiotics and blood pressure medications, can interact with calcium supplements, so you may need to take them hours apart. Your doctor can advise you on any possible interactions involving your medications and supplements.

Take-Home Message
If you currently take calcium supplements because your doctor said you were at risk of osteoporosis, then continue to take them unless or until you are otherwise advised to stop. But share your concerns with your doctor, especially if you have heart attack risk factors, and discuss possible alternatives.

“If you are taking supplemental calcium then you don’t necessarily need to meet your needs from dietary sources on a daily basis, unless you decide to decrease the supplemental calcium and replace with dietary sources,” Zampano says.

For many older adults, especially those who are lactose intolerant and don’t get enough calcium from non-dairy sources, a combination of dietary calcium and a lower-dose of calcium supplements may be the most realistic compromise.