The use of calcium supplements
Advice from the bone clinic, Greenlane clinical centre
The recent evidence from the Auckland Calcium Study that a one gram calcium supplement in elderly women was associated with an increase in risk of myocardial infarction has caused many doctors and patients to request advice regarding their use of calcium supplements for the treatment and prevention of osteoporosis. There is no international consensus around the subject at present. Our data have been presented at an Australasian and an American Meeting, but are not yet published.
One possibility is that the high doses of calcium accelerate vascular calcification. Three other recent studies of calcium supplementation in older women show similar trends, but do not reach statistical significance. While further research is being done in this area, we suggest the following approach:
- It is likely that this is primarily a problem for elderly women because they are more likely than younger subjects to have prevalent coronary heart disease. Therefore, it seems wise to advise against calcium supplementation in those over the age of 70 years and in those known to have coronary heart disease. Aiming at a total calcium intake of approximately 1 g/day (equivalent to 4 servings of dairy products) seems sensible in these subjects. For instance, in a person consuming a dietary intake of ~0.5 g, calcium supplementation should not exceed 0.5 g.
- There is very little data relating to the cardiovascular effects of calcium supplements in older men, so it may be prudent to apply the same precautions.
- We continue to recommend regular sunlight exposure or vitamin D supplementation in all people over age 70 years.
- At present, there is no evidence of adverse cardiovascular effects of calcium supplementation in younger women, so the conventional use of calcium supplements seems reasonable in these subjects.
- In patients taking bisphosphonates for osteoporosis or Paget’s disease, there is a theoretical risk of mild hypocalcaemia. Again, ensuring a total calcium intake of 1 g/day should prevent this (as above).
- There is no reason on the basis of the Auckland Calcium Study, to be advising reduced calcium intakes in children, adolescents or young and middle-aged adults.
