Tuesday, October 29, 2013


     There have been many studies and much written about calcium supplements as well as calcium plus Vitamin D and the amount of calcium in one's diet. There was an excellent review article about these matters recently published in the New England Journal of Medicine (NEJM vol. 369, pp 1537-1543, October 17, 2013) and I thought I would summarize the article here.

     First let me say that the interaction between Vitamin D and calcium is not completely understood. It is also not true that calcium supplements can  reduce age-related bone loss and the susceptibility to fracture, assuming that one has a diet adequate in the RDA of calcium. (One study did show that taking 800 IU of Vitamin D would achieve this goal.) There is therefore insufficient evidence to recommend calcium supplements in community-dwelling adults.

     The RDA of elemental calcium is 1000 mg/day for women up to age 50, and 1200 mg/day thereafter. For men, the RDA is 1000 mg/day up to age 70 and 1200 mg/day thereafter. Most people receive at least this much in their diet. The largest calcium contribution comes from milk and milk products such as yogurt and cheese. The best vegetable for calcium is raw kale, and the best fish is sardines, followed by pink salmon. Another source of calcium is fortified cereals.  Diets containing less than 700 mg/day of calcium can lead to bone loss.

     The recommended upper limits of ingested calcium is 2500 mg/day in women up to age 50 and 2000 mg/day thereafter. For men The same limits apply at the same ages.

     The most common supplements are calcium carbonate (Tums is an example of this) and calcium citrate. Calcium carbonate requires stomach acid to be absorbed, so this pill should be taken with meals, while calcium citrate may be taken at any time. The most common side effect of calcium is constipation and bloating. Some studies show that additional calcium increases your risk of developing kidney stones, and other studies show that it reduces your risk.

     It is important to note that bone meal, oyster shells and dolomite may contain lead, and therefore should not be consumed by pregnant women.

     There was one study showing that calcium supplements can increase one's risk for prostate cancer, and a larger study showing that it did not. There have been studies showing that calcium supplements increase your cardiovascular risk, as well as studies showing that it does not increase your risk, and there has been a good deal of discussion about these conflicting studies. I generally feel that if you have to argue  about the significance of data or a result, then the result is not significant.





Wednesday, October 16, 2013

Exercise is Good For You

     A very interesting meta-analysis was published online in the British Medical Journal by H. Naci (BMJ 2013:347:f5577) this month. It compared the benefits of drug therapy vs.exercise in the secondary prevention of new or worsening conditions in 4 diseases: coronary heart disease, stroke, heart failure, and adult-onset Type II diabetes. They disallowed studies in which both drugs and exercise were prescribed and  because a head-to-head study of exercise vs. drug therapy was the desired goal.

     It is well-known and documented that exercise has health benefits. There is an enhanced quality of life, fewer hospital admissions, and enhanced all-cause mortality in those who exercise. The study here reviewed meta-analyses to try to compare the benefits of drug therapy vs. exercise in mortality.

     The author reviewed 4 sets of patients: those receiving a statin for elevated cholesterol, those receiving a diuretic for chronic heart failure, those receiving anti-coagulation because of a stroke, and those receiving metformin or a similar drug for pre-diabetes. Over 339,000 patients in over 350 meta-analyses were reviewed.  The results can be simply summarized, but should not be taken as a reason to stop medication.

     No difference was found in mortality for secondary prevention of heart disease between drugs and exercise in patients with elevated cholesterol.

     No difference was found in mortality or progression to full diabetes between drug therapy and exercise.

     There was a slight advantage in exercise rather than anticoagulation or anti-platelet therapy in patients with a stroke.

     But diuretics were definitely superior to exercise in patients with chronic heart failure.

     The conclusion would seem to be that if you have any of these four conditions, be sure to start exercising if you are not already doing so, For further details, the full report is available online, whether or not you are a subscriber to the British Medical Journal.