Rethinking Calcium Supplements

Calcium is a very important nutrient - not only for bone health, but also for nerve, muscle, and heart function. So, I want to be clear up front that what I’m about to discuss pertains to supplements, not calcium in food.

Calcium supplements have been recommended for many years, particularly for post-menopausal women, as an important way to avoid osteoporosis and the risk of bone fractures that come with it. But more and more research is calling into question just how effective supplements actually are for preventing osteoporosis. There’s been some mixed results from current studies, but the highest quality studies have typically shown that calcium supplementation, at least by itself, has little to no effect on bone density.

That bit of news would be disappointing on its own, but it gets worse. Recent studies have found an association between calcium supplementation and cardiovascular disease. Taking calcium supplements appears to substantially increase the risk of heart attacks! The effect appears to be most severe in people who take calcium supplements without also supplementing Vitamin D.

The problem seems to be that calcium supplementation results in deposits of calcium in the walls of blood vessels, thereby contributing to blood vessel narrowing and impaired circulation, especially in smaller blood vessels like those that supply the heart.

But the increased risk of heart attacks and other cardiovascular issues does not appear to be related to calcium intake per se – only when it comes from supplements. In fact, it’s been found that those individuals with the highest dietary intake of calcium from foods actually had a reduced risk of blood vessel calcium deposition.

So what’s going on here?

The current theory is that taking calcium supplements causes a sudden spike of calcium in the bloodstream. The sudden high concentration of calcium is thought to result in greater deposition of it into the blood vessel walls than occurs with the more gradual increases in blood calcium that occurs with food. In addition, other nutrients in foods, such as vitamin D, facilitate the uptake of calcium into the bones, thereby shortening the duration that calcium stays in the bloodstream.

The implications are pretty obvious – get your calcium from food and not supplements. If you absolutely must take calcium supplements for some reason, be sure to also supplement with vitamin D and spread out the supplement dose as much as possible over the course of a day (for example, instead of taking 1000 mg in one dose, maybe take 250 mg four times a day).

Dairy products are the classic dietary source of calcium, but of course some people either don’t like dairy or have issues like lactose intolerance. Regarding lactose intolerance, products like Lactaid provide the missing enzymes needed to digest dairy comfortably. Hard cheeses are also an option, as they are much lower in lactose than other dairy products. But if you don’t like dairy or have reasons to avoid it, there are several other food sources for calcium.

Of course, non-dairy “milks” like soy and almond milk are usually fortified with calcium, as are other foods like some orange juice and cereals. In addition, nuts and seeds, beans and legumes, tofu, and canned fish with bones (you need to eat the bones to get the calicium), and cruciferous vegetables (such as broccoli and cauliflower) are all solid sources of calcium.

Leafy greens also are high in calcium, but some, like spinach, are also high in oxalic acid which can reduce calcium absorption, so they’re not the best option.

Finally, regardless of calcium intake, weight-bearing exercise is by far the most important factor in maintaining strong bones. Exercise places mechanical stress on the bones that stimulates the bone cells to take up calcium and without that stimulation, far less calcium winds up in the bones than in other tissues where it tends to be more problematic than helpful.

Until next time…

George F. Best, D.C.