Osteoporosis and heart disease are both strongly associated with aging. Preventing these potentially serious problems with lifestyle choices is a really good idea. But a study reported several years ago suggested that taking calcium supplements to prevent osteoporosis would increase your risk for heart disease. It seemed like medical professionals were saying “pick your poison”, so to speak.
I always had issues with these studies. One of the first ones reported lots of statistical links between calcium from diet or supplements or both with risk for heart attack. In fact, higher calcium intake from food was linked to lower risk of heart disease in women. However, people who got their calcium only from supplements had an increased risk. But only when supplemental calcium intake was very high — more than 1000 mg per day. Confused yet?
I see major problems with these sorts of studies:
- Calcium from food and supplements was all self-reported. No one actually measured the subjects food or looked at how many supplements they really took
- No one asked what form of calcium was taken. Calcium carbonate? Calcium citrate? Something else? Different forms might be metabolized differently.
- Were people taking an entire day’s worth of supplements all at once? The researchers note that absorbing a really big dose of calcium all at once could spike blood calcium briefly, leading to deposits in blood vessel walls.
- Were people taking supplements along with calcium-rich foods, thinking that would be especially beneficial? See #3 above.
- And what to make of foods that are fortified with calcium carbonate, like plant milks and ready-to-eat cereals? Were those counted as supplements rather than as food sources. They should have been in my (not) humble professional opinion.
Now along comes a better study. Calcium supplements were provided; diet was measured in 3 groups of healthy women, average age 60:
- 750 mg calcium supplement + 450 mg from diet
- 1200 mg calcium daily just from diet
- control group with no particular calcium intake recommendations
Blood vessel health was measured, along with various lab values like cholesterol. After one year, there was no significant difference in these measurements between any of the groups. Critics point out that the small number of women (121 total) and the relatively short time frame (1 year) could limit the usefulness of the data. Nevertheless, nothing turned up.
I take guidance from all of these findings. I agree that getting all or most of your calcium from supplements everyday, in big whopping doses, is a bad idea. Worse idea: taking all of that big dose at one time. Don’t do that. Even the recent study, with a daily supplement intake of 750 mg of calcium seems a tad high. I’d say 300-600 mg calcium per day from a supplement is plenty. Get the rest from food. And even then, I suggest the 600 mg days should be occasional.
Food comes with other nutrients that are important for bones — potassium, protein, phosphorus, magnesium, etc. Supplements likely have vitamin D, but nothing else. Another important point: your body can only handle about 500 mg of calcium at one time, so overloading at one meal isn’t at all helpful for your bones.
My plan: a modest 300-400 mg calcium per day in supplements, the rest from food. Supplements should not be your primary source.