Health & wellness

In Practice

Important questions about calcium

Adapted from the In Practice blog at

Certain questions come up frequently in my medical practice. Often these concern issues that have been reported heavily in the media and/or about which there is controversy.

This is the first in what will be an occasional series on this blog addressing some of the questions my patients ask most often.

One of the things about which I’m asked most commonly is calcium. Some of the confusion comes from the fact that our knowledge about calcium and health is evolving.


Here are a few of those questions , along with answers that reflect our knowledge — to date.

Why is calcium important?

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Calcium, a mineral element, is a major component of bones and teeth. Smaller amounts are also necessary for normal function of the heart and other organs.

What’s the best way to get enough calcium?

Various foods, including vegetables, fish, and dairy, are rich in calcium. Omnivores, vegetarians, and vegans can all get enough calcium in food — though it requires some effort and attention. Supplements are also available.

My blood calcium level is normal — doesn’t that mean I get enough calcium?

No. The level of calcium in the blood is tightly regulated by various hormones, the kidneys, and other organs. It does not reflect the store of calcium in the bones. In extreme cases, lack of or excess calcium intake can lower or raise blood calcium levels — both are dangerous.

Why are calcium supplements often combined with vitamin D?

Adequate vitamin D is required to absorb calcium in the intestines. Many people who live in northern climates or who don’t get outdoors lack adequate vitamin D, since sunlight is necessary to metabolize it. Various foods including fish, eggs, fortified milk, and orange juice provide vitamin D. It is a little challenging for vegans to get adequate vitamin D from food alone, but it can be done.

If I have osteoporosis (bone thinning), will increasing my calcium intake help?


While inadequate calcium (and vitamin D) intake contribute to osteoporosis, supplementing these nutrients may not cure the problem. A landmark study showed that supplementation improved bone density, but didn’t significantly lower the risk of fracture.

What’s the down side to taking calcium supplements?

Excess calcium intake can lead to kidney stones and constipation. Calcium supplements can interfere with the metabolism of certain medications. Also, some data suggest that calcium supplementation in men can cause heart disease and prostate cancer — though other studies have shown a decreased risk of cancer.

So what’s the bottom line?

Calcium is important for bone and general health and most of us don’t get enough of it. Ideally, we’d get what we need from food. If that’s not possible, supplements are available, but we can’t say confidently that these are 100% safe for everyone or that they are a fix for fragile bones.

Dr. Suzanne Koven can be reached at
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