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What One Calcium-aholic Learned Last Week
However, a recent study has deflated my hopes that calcium supplements are the magic pill to prevent fractures and osteoporosis.
In a study published in the British Medical Journal, a team led by Eva Warensjo from Uppsala University in Sweden analyzed data from more than 61,000 Swedish women that included their calcium intake and fracture rates over a period of 19 years. The researchers found that the women whose daily calcium intake was less than 750 mg increased their risk of first fracture compared to those whose intake was 900 mg a day, but women who increased their calcium even more--to over 1,137 mg per day--did not experience lower risks of fractures. The study authors concluded that gradual increases in dietary calcium above the base level of 750 mg wasn't associated with a reduced risk of fractures or osteoporosis.
So much for my theory that I could stockpile calcium.
What's more, the study authors made some surprising connections between women with the highest calcium intakes and hip fractures. This particular part of the study was picked up by the media, and suddenly women were worried about not only getting the right amount calcium but also whether they could be overdosing on the mineral.
I asked two medical experts who study calcium and bone health to help me make sense of the study and to figure out how much calcium is too much.
My first question was about the U.S. recommended daily allowance for calcium, which is 1,000 for adults, and 1,200 for women over 50. Given that the Swedish women's bones didn't seem to benefit from an intake over 750 mg, are the American recommendations too high?
Both experts believe that the current guidelines are still a good rule of thumb. "The Institute of Medicine recently re-evaluated the requirements for calcium and released their recommendations last November," says Connie Weaver, PhD, distinguished professor and head of nutrition science at Purdue University. "They've already considered dozens of studies, and that body of literature supports these recommendations."
I used this handy calcium calculator from the International Osteoporosis Federation to find out that I'm getting over 1,000 mg of calcium per day just from food. I was curious to know what was happening to the calcium that my body doesn't need. "Excess calcium is excreted through the kidneys," says Kimberly J. Templeton, MD, professor of orthopedic surgery at the University of Kansas and medical advisor to HealthyWomen.org. For women like me, who have normally functioning kidneys, an extra 200 or 500 mg of calcium isn't going to pose a problem, says Templeton. Women with kidney problems should be more cautious. "They can build up additional calcium and are more likely to develop issues with low bone density and increased risk of fractures."
Both experts chose to focus on the new study's conclusions that too little calcium leads to weaker bones, which can lead to fractures--and which underscores what other studies have found. They don't feel that people, especially post-menopausal women, should react to this study by decreasing their calcium intake below the U.S. recommended allowances. "The consequences of developing a fracture are so significant," said Templeton. "A hip fracture permanently impacts your life. It can cause depression, force you to limit activity, and spur overcautiousness that can lead to another fall. Fifteen percent of women and 30 percent of men who have a fracture from a low-impact injury will die in the first year after a fracture."
Weaver was also concerned with women interpreting this study the wrong way and being scared off from taking the calcium that they may need. "We know you benefit from getting up to at least 1,000 mg of calcium a day, and this study showed no benefit beyond that. None of the societies are saying that we should beware of high calcium. But not getting enough: We know that's a problem."
Templeton reminded me that popping pills isn't the only way to improve bone health. Weight-bearing like strength training, jogging, tennis and hiking (especially with the weight of a pack) can help stimulate bone growth, as bones react to stress by fortification. Yoga, which was shown in one study to increase mineral density in the spine, has another important bone benefits. It improves balance and coordination, says Templeton, making us less likely to fall and break something (while this is especially important for seniors, it's also a great reminder for klutzes like me).
My bone-building plan is to continue to exercise, do yoga and eat calcium-rich foods as part of a larger diet. If I'm going to overdose on calcium, I'd rather have it come from cheese or almonds than a pill--but I'm still going to take those too. The study hasn't scared me off supplements (just 600 mg a day), but it has made me curious to see how the Institute of Medicine will react to research like this. I'll be keeping my eye on their requirements.
As a reminder, always consult your doctor for medical advice and treatment before starting any program.