Recently I reported on studies showing that calcium pills do not help to prevent bone fractures. This week a well-planned study shows that taking calcium pills, both with and without vitamin D, is associated with increased risk for pre-malignant serrated colon polyps (Gut, March 02, 2018). More than 400 patients, ages 45 to 75, with a history of colon polyps, were given either:
• 1200 mg calcium pills/day,
• 1000 IU vitamin D pills/day,
• Both the calcium and vitamin D pills, or
• Placebo pills. After five years, there was no difference in polyp formation between the groups. All the pills were stopped. Six to ten years later, those given calcium pills were four times more likely than those not given calcium pills to have pre-malignant serrated polyps. As was found in other studies, those who smoked were at double the risk for colon polyps. Other studies show that serrated polyps are associated with a markedly increased risk for developing colon cancer (Gut, November 2016;67(3)). Previous studies show that colon polyps are full of Annexin A10 and calcium pills may increase concentration of that chemical.
Calcium And Vitamin D Pills Do Not Prevent Fractures A review of 33 studies shows that calcium and vitamin D pills do not prevent fractures, regardless of dose (JAMA, Dec 26, 2017;318(24):2466). Other reviews of 59 studies and 50 studies showed that neither calcium pills nor foods rich in calcium prevent bone fractures (British Medical Journal, September 29, 2015;351:h4183 ). An editorial in the same issue of JAMA states that the evidence is so overwhelming that extra calcium does not prevent fractures that we have to ask ourselves why these products are still so widely used.
Why so Many Calcium Pills? In 1994, Congress passed a law that allows manufacturers of calcium and vitamin D pills to advertise and sell their pills without having to supply evidence that their products have any health benefits whatsoever. In the United States today, more than $6 billion of calcium pills and $2.5 billion of vitamin D are sold each year. The Food and Nutrition Board (FNB) at the Institute of Medicine of the National Academies recommends 1200 mg of calcium each day for people over 50, even though they have little data to support the recommendation. In 2013 the United States Preventive Services Task Force reviewed 135 studies and recommended that postmenopausal women refrain from taking supplemental calcium and vitamin D.
My Recommendations More than 75 percent of North Americans spend 12 billion dollars a year on supplements that are largely unregulated by the government to check whether they work or are even safe. Calcium and vitamin D pills are particularly popular because people believe that they strengthen bones, yet the recent studies shows this is not true. More than 54 million North Americans have osteoporosis that causes more than 30 percent of the women over 50 to break their bones. I recommend that people who have weak bones or suffer fractures should:
• lift weights if they are able
• do weight-bearing exercise such as walking, jogging, dancing and playing tennis
• restrict alcohol
• avoid smoking and second-hand smoke
• get calcium from foods, not from pills. Calcium-rich foods include dairy products, tofu, nut milks, leafy green vegetables, nuts and fish such as salmon and sardines
• keep blood levels of hydroxy vitamin D over 20 ng/ml. Sunlight is the best source of vitamin D; if that is not an option, use vitamin D pills, even though they have not been shown to prevent fractures.
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