The calcium issue was raised by Dr Ian Reid of New Zealand. He and his colleagues re-analyzed data from the Women Health Initiative (WHI) which looked at calcium and vitamin D supplements. The initial study of 36,000 women showed no increased risk for heart disease among those who received 1,000 milligrams of calcium and 400 international units (IU) of vitamin D per day, compared with those who were randomly assigned to receive a placebo. However some of these women were also taking calcium supplements, which may have affected the results. To take this into account the New Zealand researchers analyzed the results for a subgroup of 16,718 women who were not taking calcium and vitamin D supplements at the beginning of the WHI study. It is the data for these specific women that showed those taking the supplements were at greater risk of heart attacks. A possible explanation is that the sudden change in blood calcium levels when starting the supplement is responsible for the increased risk. Women who already took the supplement had enough calcium in their blood not to be affected by a spike in calcium levels.
Does this mean that women should stop taking calcium supplements? Not according to Dr Jo Ann Manson, the author of the WHI study. For her, the selective re-analysis of a very specific subgroup does not negate the fact that overall there is no evidence of an association between the use calcium and vitamin D supplements and an increased risk of heart attacks.
It all depends on your personal health history. If you are at risk for heart disease, you may want to make sure that you are not “overdosing” on calcium. On the other hand if osteoporosis is a concern it is essential that you have a sufficient intake of calcium.
You should calculate how much calcium you are getting from you diet, including from the fortified orange juice. If you are over 50, make sure it equals 1,200 mg. If it does not, it is OK to take calcium supplements to bring it up to that amount.