Men's Osteoporosis Support Group

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Calcium supplements to increase BMD

Arch Intern Med. 2008 Nov 10;168(20):2276-82. Randomized controlled trial of calcium supplementation in healthy, nonosteoporotic, older men. Reid IR and others. PMID: 19001206. Few research studies involve healthy, non-osteoporotic men, but this is the exception. Healthy males received either 1200 or 600 mg of supplemental calcium over a two-year period and received bone mineral density (BMD) tests comparing the effect to placebo. There was no difference between placebo and the men taking 600 mg/day of calcium. There was, however, a statistically significant 1% to 1.5% increase in BMD compared to placebo in the men taking 1200 mg/day of calcium. Three other tests showed statistically significant differences when the men took 1200 mg/day of calcium: serum parathyroid hormone, total alkaline phosphatase activity, and procollagen type 1 N-terminal propeptide, 25%, 8% and 20%, respectively. Regarding side effects, tooth loss, constipation, and cramps were not affected by calcium supplements, but vascular events tended to be more common in the groups receiving calcium supplements. The authors conclude: "Calcium, 1200 mg/d, has effects on BMD in men comparable with those found in postmenopausal women but a dosage of 600 mg/d is ineffective for treating BMD."

Editor's comments. In general I'm not impressed with any effect on BMD from calcium supplementation in the studies I review. In, for example, a trial on one of the bisphosphonates, the control group always gets calcium and vitamin D supplements while the test group gets that plus a bisphosphonate. In general the control group loses BMD and the test group gains BMD. Often the control group does get less than 1200 mg/day of calcium, so that might be part of the issue. But the Reid and others study shows a statistically significant effect from 1200 mg/day of calcium in normal, healthy males. This is suggestive that such men should be taking calcium supplements or getting that much additional calcium in their diets. It is possible that individuals with osteoporosis have issues that negate the effects of calcium supplementation such that they might not benefit in the same manner. Since no such individuals were included in this study, that is only conjecture.

There are other possible considerations when looking at calcium intakes. For instance a study in Germany examined the calcium balance for vegans and lactovegetarians and found a positive calcium balance of 119 mg/day in the vegans and 211 mg/day in the lactovegetarians. This while calcium intake was an average of 843 mg/day in the vegans and 1322 in the lactovegetarians. The positive calcium balance means the bones are not being used to replace calcium lost in the body due to excess acid produced by certain food products, and thus BMD should remain normal or increase in such individuals. See J Bone Miner Metab. 2003;21(1):28-33. Calcium balance in young adults on a vegan and lactovegetarian diet. Kohlenberg-Mueller K, Raschka L. PMID: 12491091.

There is a lengthy discussion of this topic under the heading of potential renal acid load (PRAL) in the October 1, 2000 Newsletter on this site. It is a controversial topic, but some feel that excess protein intake, which is acidic in nature, can lead to BMD loss as the bones are used to reduce the excess serum acid build up. Thus, vegetarian diets, especially vegan diets with no meat or dairy, tend to be low in protein and high in pH, thus incapable of producing excess serum acidosis.

Another 2008 study suggests that monitoring urine pH may be a good way to see if the diet is high or low in PRAL, and thus be a proxy for the dietary effect on BMD. They note that the more alkaline diet (low PRAL) that vegetarians have, with high intake of fruit and vegetables, was associated with significantly more alkaline urine pH (higher pH value). So it might be possible to monitor your need for calcium supplements by checking urine pH. There would be greater need for supplements as the urine pH went down. See Br J Nutr. 2008 Jun;99(6):1335-43. Urine pH is an indicator of dietary acid-base load, fruit and vegetables and meat intakes: results from the European Prospective Investigation into Cancer and Nutrition (EPIC)-Norfolk population study. Welch AA and others. PMID: 18042305.

I have kept almost all my medical records over the years, so I went through to see how many times a urine pH was done. My most recent test in March of this year, after I had started a vegan diet, had a pH of 8.0, the highest I ever had. I tended toward vegetarian over the last several years, but noted several urine pH results before that in the 5 or 6 (acid) range. So, in my example of one, there seems to be some correspondence with what you would expect for someone monitoring urine pH while on a vegan diet. What would be interesting would be to see if meat eaters find their urine pH to be acidic and could then raise the urine pH by simply adding calcium supplements. I could imagine that the frequency of supplementation during the day might be important, too. That is, spreading out the dosage at meal time might raise urine pH more than just taking one dose per day. There should be more research coming in this area that should clear up these issues.

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