20 April 2011
An article in the British Medical Journal (BMJ), reported in today’s press, has suggested that calcium supplements, which many people take in the hope of avoiding osteoporosis, may increase the risk of heart disease and stroke.
The initial findings were based on the Women’s Health Initiative, an observational study. If they had relied on this study alone, the investigators would have laid themselves open to the criticism of observational studies that the people were at increased risk anyway. This would have been similar to the findings years ago through observational trials that HRT appeared to prevent cardiovascular disease until it became clear that this group of people were at reduced risk for other reasons.
As I sideline, the most depressing afternoon I have spent was hearing an American professor presenting the first randomised controlled study figures on œstrogen and the fact that it did not reduce cardiovascular disease. Look at any book on Women’s Health published in the mid-nineties stating that œstrogen massively reduced cardiovascular risk and you’ll see what a hammer blow this was.
However, the investigators forestalled this criticism by looking at randomised controlled trials of calcium supplements and discovered that their findings were confirmed.
What do we make of this?
Firstly there are doubts as to whether calcium supplements are effective at reducing fractures due to osteoporosis anyway.
Secondly, there is no increased cardiovascular risk in increasing calcium in the diet, notably with milk, and this does reduce the risk of osteoporosis.
Therefore it is probably wise for people to avoid calcium supplements until more evidence accrues and concentrate on increasing calcium in the diet.
And, if you are worried about the cholesterol content, fully skimmed milk is the richest in calcium. Heads you win, tails you also win.