The most frequent supplement question I’ve been hearing lately is about taking calcium. These questions have been inspired by a recent study of calcium supplementation, which received a great deal of attention. The authors of this study combined data from other studies and determined that calcium supplementation increased the risk of heart attack.
Most of us get way less calcium in our diets than is recommended. Calcium is vital to a broad range of biological processes (heart rhythm, immunity, cancer protection, etc) and not just bone formation, as some assume. Calcium is unlike most other dietary nutrients in that it is so vitally important that the body maintains a huge stockpile of the nutrient (our bones) and then routinely breaks into that store to maintain a precise level in the blood. The body works very hard to keep calcium blood levels in that very narrow range, and even slight deviations occur only with serious problems.
Long ago our ancestors consumed much more calcium than we do. Today calcium supplementation is both common and apparently necessary, as so few of us consume recommended levels in our diet.
There have been hundreds of clinical trials involving calcium and heart disease. They only used the data from 15 of those studies. Demonstrating their own lack of understanding and naivete, they repeated the erroneous conclusion that calcium does not build bones (You can dig back in my old newsletters to read my discussion of that very poor study which they cited, but in fact proved just the opposite). If the increased risk of heart attack was meaningful, one would expect the risk of death from heart attack to also increase. It did not. Because they are they same process, only in different parts of the body, the risk of stroke should also have increased, but it did not.
In a lamentable declaration of enthusiasm for medication and radiation, one of the study authors recommended that patients get bone scans and wrote “If their risk is high, they should consider using medications rather than calcium supplements”. Reflecting a similar promedication bias, an accompanying editorial written by English cardiologists recommended “Given the uncertain benefits of calcium supplements, any level of risk is unwarranted…. On the basis of the limited evidence available, patients with osteoporosis should generally not be treated with calcium supplements, either alone or combined with vitamin D, unless they are also receiving an effective treatment for osteoporosis.” They also recommended diuretic drugs, which theoretically might increase bone density, while claiming that supplements are ineffective, dangerous and a waste of time.
Ignoring calcium and D, this is like dumping synthetic fertilizer on your garden without giving the plants water and sunshine. Not terribly smart.
Magnesium and calcium both compete and complement each other metabolically. Too much of either relative to the other can create risks. Similarly, as calcium barely dissolves in water and most people drink too little water, ignoring fluid intake can lead to false conclusions. As you have probably anticipated, I will also criticize their overlooking the influence of vitamin D, which is essential to most aspects of calcium metabolism and perhaps the most glaring vitamin deficiency in the world.
One of the world’s foremost experts on calcium metabolism, Dr Robert Heaney, commented that the paper was highly suspect. His group had conducted many of the studies reanalyzed by the investigators in the current meta-analysis. Heaney also said that, using the same data, the New Zealand investigators reached the opposite conclusions than his group and chose not to include data from other studies conducted by Heaney’s group.
I am especially interested in Dr Heaney’s comments, for several reasons. He is a member of the panel that sets recommended calcium intake levels in the US. Several years ago he wrote an extremely interesting article on the very high calcium intake of our ancient ancestors and the broad health impacts of calcium. He was also one of the handful of speakers at the first national medical meeting focused on the growing body of information on vitamin D. I spoke to him at that meeting, specifically questioning whether recommended calcium levels were too high, as they ignored widespread vitamin D deficiency. He convinced me that that was unlikely.
I am also a bit uncomfortable about this new study for a couple of unusual reasons. First, the lead author has been an investigator in many of the negative studies of calcium supplementation. That is more notable, given that the majority of clinical studies have not reached negative conclusions. Secondly, the team of investigators reside in New Zealand and are funded by the New Zealand government. As milk is an important income source for the country, they often fund investigations which tout the health effects of milk. This includes milk as a calcium source compared to supplementation. However, neither of these is proof of bias.
My conclusions are:
1) As I have instructed so many of you in the office - diet is best (see list at-
http://www.carlstonmd.com/docs/calcium.htm)
2) The recommended calcium intakes are reasonable. If you eat a lot of meat, you might need a bit more, or a bit less if you don’t.
3) Looking at dietary logs of many thousands of patients over the last 30 years, I can confidently state that most of us need to supplement our dietary calcium intake.
4) The kind of calcium supplement is important (calcium citrate and calcium malate are the safest and best absorbed)
5) Other factors like water, magnesium and vitamin D are essential to proper absorption and utilization of calcium.
