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Calcium is the most abundant mineral in the body – and lately, it’s been one of the most ubiquitous buzzwords in the news, thanks to a couple of controversial reviews.
Researchers in New Zealand, for example, have reported that calcium supplementation is associated with a higher risk of heart disease among postmenopausal woman, while Cochrane Reviews has stated that taking calcium in your younger years is “unlikely to reduce the risk of fracture, either in childhood or later life.”
What to make of this mineral bashing? According to Connie Weaver, PhD, distinguished professor and department head of nutrition science at Purdue University, and director of the Women’s Global Health Institute, calcium is still as essential as ever. On the eve of her upcoming paper on calcium and cardiovascular function, the author of Nutritional Influences on Bone Health discusses the nutrient and the news.
When and why did nutrition scientists realize that calcium was essential for good health, especially among active women?
Calcium has long been known to be an essential nutrient. However, the public became aware of osteoporosis and the importance of calcium in preventing bone loss in the late 1980s.
What is your response to the recent Cochrane Review that found calcium supplements taken by children had minimal effect on bone density?
Calcium supplements were found to have significant benefits to upper-body bone mineral density. For children, bone mass is more important than bone density because it accounts for growing size, so I think they picked the wrong outcome variable. Regardless, short-term trials of calcium supplementation do not represent the value of calcium in the diet throughout life. In the trials, they do not have a good way of assessing calcium intake from diet. So if the diet is already adequate in calcium, you would not expect a benefit from supplementation. Further, compliance with supplements is poor, especially in children.
What about the New Zealand researchers claiming that calcium increases the risk of heart disease?
Mark Bolland and Ian Reid did a retrospective analysis of a calcium-supplementation trial designed with bone outcomes to assess any side effects and found an increase in myocardial infarction in the supplemented group. They then did a meta-analysis and found other cardiovascular risks, but over half of the subjects in this analysis self-reported their symptoms, which were not validated by medical personnel. These criticisms and no dose-response relationship have caused many to doubt whether calcium supplements cause a risk. It received so much media attention that supplement sales declined and physicians became worried about recommending supplements to their patients. The observation has spawned many new retrospective analyses and epidemiological studies with mixed results. None of these studies directly tested tissue damage or calcium deposits in a controlled manner. A new paper is coming out from our research group where we tested high levels of calcium from dairy or calcium carbonate (the most common supplement form) on coronary artery calcification and function in pigs that are vulnerable to cardiovascular disease. The high levels of calcium in the diet posed no increased risk of any measure of cardiovascular function or calcium deposition.
What is the best way for women age 30 to 50 to get calcium?
The Dietary Guidelines for Americans recommends 3 cups of milk or equivalent daily. A practical suggestion is for every serving of milk (or yogurt, cheese or calcium-fortified beverage) missed, take a supplement containing 300 milligrams of calcium each day. Keep in mind that dairy products and many fortified foods contain other important nutrients for bone health, so be sure to get other sources of magnesium, potassium and vitamin D if you avoid dairy.
See also Low-Fat Dairy? Not So Fast.
Are there other diet and lifestyle changes you can make to ensure adequate calcium intake?
Three servings equivalent to 300 milligrams of calcium per day as in a glass of milk or 1 cup of yogurt or 1.5 ounces of cheese is recommended. So, think of a calcium-rich source with every meal. Weight-bearing exercise is also important. We have studied the interaction of calcium and exercise in young women and have shown the benefit of both of these lifestyle choices working together. You need the raw materials to build bone as well as the loading of the bone for your body to use it. When bone is not loaded, it shrinks from disuse rather quickly.