Calcium Supplements: A Bone Health Staple Or A Contributing Factor For Heart Disease?

Everyone knows calcium is important for strong bones, but is our pill-popping habit helping or harming us?

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With nearly half of all Americans (and 70 percent of older women) claiming to supplement with calcium, you would think that its benefits would be pretty well established.

We do know that calcium is important for health. It’s the most abundant mineral in the body, with a whopping 99 percent of it found in bones, where it aids in both structure and function. The remaining 1 percent contributes to vascular contraction, vasodilation, muscular function, nerve transmission, intracellular signaling, and hormonal secretion.

So, yeah, calcium is kind of a big deal.

We also know that many Americans do not get enough through diet alone. Dairy might get the most attention, but it’s not the only food bringing its calcium game. In fact, sardines packed with bones contain more calcium than eight ounces of milk, and the calcium found in the kale family (kale, broccoli, cabbage, turnip greens, and bok choy), although found in smaller quantities, is comparable in “bioavailability.” (That’s a good thing.) Additional sources include almonds, Brazil nuts, dried figs, fortified tofu, and (my personal favorite!) blackstrap molasses.

Calcium’s important roles in the body—paired with our tendency to under consume it—should make supplementation a no brainer, but as with many health habits, it is not so cut and dried.


The mixed results of the Women’s Health Initiative, which looked at 36,282 postmenopausal women, has raised some notable red flags. It found that daily supplementation of 1000 mg calcium with 400 IU vitamin D for seven years did not lead to any significant decrease in colorectal cancer, and that women who started supplementing during the study actually wound up with an increased risk of cardiovascular events. These women also had a 17 percent higher risk of kidney stones than women on a placebo.

The finding regarding calcium supplements and heart disease, in particular, has been receiving attention lately. Researchers can’t say for sure, but their concern is that high calcium intakes, especially from supplements, can lead to calcium deposits in—and subsequent hardening of—arteries, a known risk factor for incidents such as heart attacks. This area of research needs more attention before any changes to guidelines occur, but it’s certainly something to pay attention to moving forward.

Nonetheless, the U.S. Preventive Services Task Force (USPSTF) recently concluded that there is actually no benefit to supplementing calcium in doses smaller than 1,000 mg and that the data is insufficient to support higher doses as well. They ultimately no longer recommend the majority of Americans take calcium supplements at all.


Let’s not forget that we know that a dietary calcium deficiency can lead to osteoporosis, and segments of our population are more at risk than others. Women who are postmenopausal, amenorrheic, or suffering from female athlete triad; vegetarians and vegans; smokers; and anyone with a family history are particularly susceptible. Even if we shouldn’t prescribe preventive calcium supplements to every American, that doesn’t mean that it’s not advisable for certain demographics.

In fact, despite the risks many experts conclude that calcium supplements are probably a good idea for women with osteoporosis or broken bones over the age of 50.

We need to see more consistent results across studies before we jump to any new conclusions. Repeat research doesn’t happen nearly as often as it should, leading to single, flawed studies making big headlines. One of the biggest challenges and criticisms of the research, for example, is that adherence is poor; it’s hard to study a supplement’s effect if the participants forget to take the prescribed dose. If everyone took the pills as instructed, perhaps the results would be more definitive.


FIT…but only if necessary. We need to focus first on calcium-rich foods. Dietary calcium has all of the potential benefits without any of the purported risks of supplemental calcium. Use the money you’ll save by not buying the supplements on buying more nutritious foods, and you won’t have to be bothered with popping a pill every time you eat.

If you do choose to supplement as a high-risk individual, find a high-quality one, preferably with a USP seal to ensure that it’s been independently tested for contamination and quality. Definitely do not take more than the 1,000 to 1,300 mg daily dose (depending on your life stage and sex). Split your daily intake into less than 500 mg per sitting, which is crucial for proper absorption, and ideally go for one that’s also packed with some vitamin D, magnesium, phosphorus, and vitamin K.

Supplemental calcium may make us healthier in the short term, but don’t let it be a crutch or an excuse to not turn to those calcium-rich foods first. Medicine saves millions of lives, but remember, nature is pretty remarkable, too.

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