Calcium: Everything You Need To Know

Google has this handy little widget, now. Search any medical term, and, on the results page, a sidebar pops up, running down the basics of the disease or ailment.

Type in “diabetes” and you’ll get a Cliff’s Notes–worthy explanation of types 1, 2, and gestational diabetes. “Common cold” brings up an illustration of a kid sneezing into a tissue alongside bullets on symptoms and treatments. With “osteoporosis,” you get the image of an older woman reaching down to lift groceries into her car trunk. Her shoulders are hunched, and the artist has rendered her back as transparent, so you get a look at her slightly curved spine. In the inset representing the density of her skeleton, the detail looks more like Swiss cheese than hip bone.

Scary, right? It reminds me of how, when I was a kid, my mom used to convince us to finish our glasses of milk at dinner—by telling my sister and I all about how women who don’t get enough calcium end up developing osteoporosis. But milk has calcium, and calcium gives you strong bones, so drink up, right? Supporting skeletal health is the basis of most calcium supplements’ value.

But a daily calcium supplement might be the opposite of what you need. Even though getting a regular dose of calcium is pretty important it seems that lifestyle factors like diet and exercise play a more important role in bone health than supplementation—and depending on your health concerns, taking a pill might be downright detrimental.

The function of calcium

Osteoporosis—a condition in which bones soften and leech calcium, eventually weakening them so much that they become brittle and break—affects over 10 million American adults. Eighty percent of those affected are women (menopause increases bone resorption and decreases calcium absorption), and according to the National Institutes of Health the condition is to blame for 1.5 million bone fractures a year [1].

Because 99 percent of the calcium in our bodies is found in teeth and bones, it’s pretty clear the mineral is important for bone health [2]. But it’s not just good for building skeletal structure—1 percent of the calcium we ingest helps keep blood vessels healthy and flexible, encourages normal muscle function and nerve transmission, and assists with balancing hormones.

Although bones undergo the biggest changes during childhood, adolescence, and early adulthood, our skeletons are constantly remodeling themselves as they absorb and resorb nutrients. As infants, we can utilize about 60 percent of calcium ingested, but by adulthood that number drops to 10 to 15 percent and slowly decreases even more as we age. So it’s incredibly important to get enough calcium as a kid, and equally necessary as an adult.

Potential problems with calcium supplements

Clearly getting daily calcium is important, so if you don’t drink milk regularly then a supplement is a simple swap. Right?

Not exactly. For many years calcium supplements were highly recommended for populations at risk of deficiency (postmenopausal women, female athletes, and those who avoid dairy), and even to perfectly healthy people.. But more recent research indicates that calcium, in supplement form, is not absorbed as well [3] [4]. In fact, after viewing 135 separate studies the United States Preventive Services Task Force recommended that postmenopausal women refrain from taking calcium supplements as they clearly do not prevent fractures in healthy women [5]. In 2007, an article published in the American Journal of Clinical Nutrition found that taking calcium supplements not only didn’t decrease fracture rates in women, it actually increased the amount of hip fractures.

Taking calcium supplements also poses a threat to heart health. Scientists from the University of Auckland discovered that, in people who took calcium supplements without additional vitamin D (which improves absorption), the risk of heart attack rose by 30 percent. And a meta-analysis by the British Medical Journal examined the results of 15 trials involving more than 12,000 people and found that those who  supplemented with calcium increased risk of heart attack by 31 percent, stroke by 20 percent, and death from all causes by 9 percent.

Where to find calcium

It’s pretty important to note that these studies only examined the effects of calcium supplements—not dietary calcium. Calcium from food sources is more efficiently absorbed by the body and getting your daily dose from food can increase your lifespan. Researchers think that it’s safer, too, because supplements hit your body with a large dose all at once. This could cause clotting, hence the increased rate of heart attack and stroke. When you eat your calcium through natural food sources, you’re getting it in smaller and more frequent increments, which your system can then absorb without clotting.

And there are actually plenty of ways to get calcium, even if you’re not into dairy. Here are some of the most common dietary sources:

• Almonds
• Beans
• Broccoli
• Cheese
• Dandelion greens
• Figs
• Hazelnuts
• Milk
• Pistachios
• Seaweeds
• Sesame seeds
• Spinach
• Tofu
• Yogurt

Should you take a calcium supplement?

It depends on a few factors. For those under the age of 25, getting the daily recommended value of calcium is pretty important, and there don’t seem to be any health risks for younger people who use a supplement (although dietary calcium is still ideal). Beyond that, it’s probably safer to rely on diet for daily calcium intake—unless you’re a “[woman] with osteoporosis or broken bones after age 50 or those with significant risk factors for fracture,” according to the National Osteoporosis Foundation. And before you begin a supplement regimen—or if you have any questions about whether you need more calcium—check in with your doctor.

All ages can increase bone density naturally by engaging in weight-bearing and strength-building exercise. This includes things like running, jogging, weight lifting, and even yoga [6]. So if you’re worried about future bone health, it might finally be time to buy that yoga mat—and maybe some kelp noodles, too!

Wanna know more? Check out the rest of our vitamin primers here:

• Vitamin A
• Vitamin B
• Vitamin C
• Vitamin D
• Vitamin E
• Magnesium

Illustration by Foley Wu