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Bone Health: More Controversy Over Calcium and Vitamin D
Every woman wants to do all she can to prevent osteoporosis, but the information about calcium and vitamin D supplements is becoming muddied and many women are confused about what to do.
Calcium supplements, with or without vitamin D, are widely used by women for the prevention and treatment of osteoporosis. Now a new study combines a reanalysis of the data from the Women’s Health Initiative Calcium/Vitamin D Supplementation Study (WHI CaD) with a meta-analysis of eight other studies. The results paint a confusing picture for women who have been dependent on supplements to meet their calcium needs.
Initially, the WHI CaD study showed no adverse effect of calcium and vitamin D on cardiovascular health though some previous studies had. According to the WHI CaD researchers, though, their results were obscured by the fact that 54% of the participants were taking personal calcium supplements on their own, and 47% were taking personal vitamin D supplements. The results of the new study suggest that whether they contain vitamin D or not, calcium supplements increase the risk of heart attack by 25% to 30% and stroke by 15% to 20%. For every three factures that are prevented by calcium, six heart attacks or strokes occur, according to the paper.
So is it time to reassess the whole idea of supplemental calcium and vitamin D for the prevention and treatment of osteoporosis? Is the generally accepted practice of taking the RDA for calcium (1200 mg) in supplement form considered overkill now? Should a woman factor in her usual dietary intake of calcium and supplement up to 1200 mg per day? Or should calcium supplements be taken out of the picture altogether?
Contacted via email, Dr. Ian Reid, Professor of Medicine and Endocrinology at the University of Auckland and one of the authors of the study, stated that believes the latter. "I believe our data indicates that calcium supplements should be abandoned for most people, but that is not yet universally accepted." Even though he believes a woman should have a risk assessment for osteoporosis, he said he still believes calcium supplements should be avoided altogether.
Concerning the confusion over vitamin D supplementation and testing, Dr. Reid stated, "Opinions are divided here. At high latitudes, many older people do become vitamin D deficient, so routine supplements may be advisable." However, he said, "Many of the tests used are unreliable and they are expensive. There is also disagreement regarding the definition of deficiency which makes this area even more confusing."
According to Dr. Reid, "My advice is don’t take calcium supplements. Take vitamin D if you live in a non-sunny area, seldom go outside, or have dark skin. Have your risk of fracture measured with bone density. If the risk is high, consider taking an approved medicine to reduce that fracture risk."
Dr. Leroy Leeds, Director of the Dexa Bone Densitometry Center at Obstetrical Gynecological Associates and Clinical Associate Professor in the Department of OBGYN at Baylor College of Medicine in Houston, Texas, believes otherwise: "I feel that calcium and vitamin D are essential to build and maintain bone. It's like building a brick house. You need a wheel barrow to bring the bricks from the brick pile to the house (vitamin D) and the bricks are the calcium. I therefore recommend that a woman get 1000 to 1400 mg/day (from food and calcium supplements) and 800 to 1200 IUs of vitamin D-3." He also recommends that women engage in weight bearing exercise (walking, jogging, treadmill, or aerobic exercise) equivalent to walking a mile a day five days a week.
There are a number of other things a woman can do to help to protect her bones, whether she chooses to take supplements or not. Maintain a healthy weight; avoid excessive consumption of salt, protein, caffeine, and alcohol; don't smoke. A nutrient-rich diet that provides adequate amounts of other nutrients involved in bone health, such as vitamin K, phosphorus, magnesium, and fluoride, helps to form and stabilize the structure of bones. Because muscle strength and bone strength go hand in hand, weight-bearing physical activity and strength training provide protection against bone loss. Prescription drugs are available that prevent or delay bone loss, and some that stimulate the development of new bone. Women should speak with their physician about their personal risk of osteoporosis and decide if a prescription drug is right for them.
The study was published online April 19, 2011 in the British Medical Journal and can be accessed here.
May 5, 2011