More questions about calcium answered
Are dairy products the problem or is it the calcium they contain?
Because milk and dairy foods supply so much of the calcium in the typical diet, it's hard to tease them apart when using data from epidemiological studies. With ovarian cancer, there's reason to believe that dairy products are the culprit because of evidence pointing to intake of lactose, the sugar in dairy foods, as a risk factor. With prostate and colon cancer, the evidence points to calcium itself.
Is it better to get your calcium from supplements or from food?
Studies have repeatedly found that we're far better off getting most of our nutrients from food rather than from pills. With calcium, it's more complicated. In many ways, dairy products, and milk in particular, are an ideal source of the mineral. The calcium content is high and easily absorbed. But when dairy comes into the diet, saturated fat comes with it, and high saturated fat intake increases the risk of heart attack, stroke, and other cardiovascular problems. A few studies suggest that dairy food itself increases the risk of certain cancers (see the answer above). Of course, people can easily get around the saturated fat problem by buying nonfat products, but not everyone likes the taste of those nonfat products. Many vegetables are a good food source of calcium, but spinach, chard, and a few others also contain oxalate, and the presence of oxalate interferes with the absorption of calcium.
Food is still the best way to get calcium, with the best choices being nonfat dairy products (in limited amounts), certain types of fish (salmon, sardines), and certain vegetables (kale). Whether you need to "top it off" with a supplement depends on your diet and whether you're trying to adhere to the official recommendations.