Calcium supplements: should you take them?

Marketers in the 1980s got part of it right with their “Milk. It does a body good” campaign. Milk stayed an American household staple well through the decade, long enough that the tagline was replaced with the more famous “Got Milk?”

But, as vegans and people with lactose intolerance perhaps most keenly know, it’s not the milk your body needs but rather the calcium.

Calcium is the most abundant mineral in the human body and has quite a reputation for building strong bones. But that’s far from this mineral’s only role in the body and, in fact, only a small part of its role in bone health.

In addition to preventing or, in some cases reversing bone loss, calcium helps your blood clot and keeps your heart beating. It may even help lower both systolic and diastolic blood pressure (Palta, 2014).

Though the ’80s milk campaigns made it seem like calcium helped with muscle growth, getting the recommended amount of calcium is more crucial for nerve and muscle signaling. It’s used as a messenger throughout the body, helps with vascular contraction and vasodilation to regulate blood pressure, and plays a role in the secretion of hormones like insulin.

If you think you need a calcium supplement to ensure you get enough of this mineral to carry out those critical jobs, here’s what you need to know.

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For most people, calcium supplements aren’t necessary. True deficiency is uncommon in the United States, and it’s easy to work many calcium-rich foods into your daily diet—more than enough to meet your recommended dietary allowance (RDA).

But there are certain groups of people for whom dietary calcium may not be enough. For these people, a supplement may be helpful or even necessary. Adult women need more calcium than men and start excreting more calcium earlier than men, potentially losing bone mass, around the time they go through menopause. A dietary supplement may help meet these changing needs.

There are also lifestyle factors that potentially make calcium supplementation necessary. Although dairy products are far from the only food sources of calcium, they are some of the most potent sources.

That means vegans may struggle to meet their daily needs through diet alone. People following a high-protein, high-sodium diet, like many athletes, may also need supplements. These diets cause your body to excrete more calcium than the average adult, which means you’ll either have to plan more sources into your weekly menu or turn to a supplement to fill the gap.

Some people may get enough but have issues absorbing the mineral, creating a need for a supplement. Gastrointestinal conditions such as Crohn’s disease and inflammatory bowel disease impede your body’s ability to absorb the mineral. Some medications, such as corticosteroids, also disrupt proper calcium absorption in your body.

And although we mostly think about how calcium is needed to prevent osteoporosis, it can also help reverse this serious condition. Calcium is moved constantly in the body during bone remodeling. With enough calcium, bone density can be restored. But people with osteoporosis need to ensure they’re getting enough, often through supplementation, for this process to take place.

Healthy bones and a strong, steady heartbeat are obvious benefits of getting enough calcium. But beyond the ways that calcium keeps your body functioning properly, there are potential health benefits to keeping your calcium levels within the normal range.

May reduce the risk of colon cancer

An extremely large study that used data from 293,907 men and 198,903 women found that higher intakes of this mineral from calcium-rich foods or dietary supplements were associated with a lower risk of cancer and, specifically, cancers of the digestive system.

But, specifically, the biggest difference was observed with colon cancer, and researchers noticed specifically that as supplemental calcium increased, rates of this particular cancer dropped (Park, 2009). 

An earlier meta-analysis of 10 studies also found that higher calcium intake was associated with a lower risk of colorectal cancer, but not all of the studies included were focused on supplements. The bulk of the work looked specifically at calcium intake from milk (Cho, 2004).

May help improve metabolic markers

More research needs to be done here, but the findings of some studies offer hope that you may reap some metabolic-specific health benefits from these supplements. 

One study, for example, found that supplementation with calcium and vitamin D improved metabolic markers, specifically blood pressure and inflammation markers, in pregnant women (Asemi, 2016). 

Another found that similar supplements combining calcium and vitamin D improved inflammation and oxidative stress markers in overweight women with polycystic ovary syndrome (Foroozanfard, 2015).

But findings from studies are far from unanimous. Researchers found that dieters given these supplements saw no improvement in metabolic markers such as triglyceride levels and blood pressure in another study (Reid, 2009).

May help with weight loss

Research has found that there’s an association between low calcium levels and higher body mass index (BMI). But the relationship needed clarifying. 

A later study that gave overweight participants calcium supplements shed some light, however. All of the participants were put on a calorie-restricted diet, but only one group was given 600 mg calcium supplements. The calcium supplementation group lost more fat by the end of the study than those not given the mineral (Zhu, 2013).

More work needs to be done, however, to see if this effect still holds in people with blood calcium levels in the normal range. All of the participants in this study had very low calcium intake.

The supplements they took were also a combination of vitamin D and calcium. While vitamin D does boost calcium absorption, it’s unclear whether the fat loss was caused specifically by the mineral since vitamin D has health benefits that may promote healthy body weight, such as regulating blood sugar.

Although you won’t see as many types of calcium supplements as you will with other minerals, such as magnesium, there are a few to choose from.

The types of supplements you’ll see are chews, powders, capsules, and liquids. But the biggest difference between them is not how you take them but rather the form of calcium they use in their formulation.

The two most common types of calcium you’ll find in supplements are calcium carbonate and calcium citrate. These different forms are compounds, and they each contain a different amount of elemental calcium. 

Calcium carbonate is the cheapest form, but it does contain 40% elemental calcium. So you’re not only paying less for the supplement but also getting higher amounts of calcium with small amounts.

So what’s the downside? The potential side effects. This form of calcium is more likely to cause gastrointestinal discomfort with symptoms like bloating, constipation, and gas. It should also be taken with a meal to ensure proper absorption.

Calcium citrate is more expensive and also less concentrated. It’s approximately 21% elemental calcium, but it’s much more readily absorbed and doesn’t need to be taken with a meal (Straub, 2007).

There are certain people for whom this is simply the best choice for calcium supplements; due to its lower incidence of GI side effects, this is the form suggested for people with irritable bowel syndrome. It’s also the best form for people with low stomach acid.

The third form of supplement is really only seen in a medical setting. Calcium gluconate is generally administered through IV by a medical professional. It’s used to treat sensitive conditions like tetanic seizures caused by hypocalcemia, low calcium caused by hypoparathyroidism, and calcium deficiency caused by pregnancy or rapid growth in children.

Here’s where a little math and a look into your daily diet are necessary. Calcium supplements should only be used to close the gap between your dietary intake and calcium needs.

In order to get the right dosage for your supplement, you need to know exactly how much calcium you’re getting through food sources—and that can be tricky. Remember to include both calcium-rich foods like kale and sardines as well as fortified foods, those that have vitamins and minerals that never existed in them added back in, such as orange juice.

Forgetting to consider these sources may result in accidentally taking too much calcium, which could also lead to health problems. So if you’re an adult man and your daily needs are 1,000 mg of calcium, and you get 500 mg of the mineral from low-fat dairy foods each day, you only need a 500 mg supplement.

This is generally fine for a supplemental dose. If, however, you need to fill a larger gap in your diet, you may need to split up your dose. Our bodies have a hard time absorbing more than 500 mg at a time. Combination calcium and vitamin D supplements will help your body put the mineral to use, but larger doses should still be split throughout the day.

For most otherwise healthy adults, short-term use of calcium supplements will have few side effects. You may experience gastrointestinal issues like gas, bloating, and constipation.

But for some people, supplements simply may not be a good fit. Calcium may interact with certain medications for osteoporosis, seizures, thyroid trouble, and Paget’s disease. Some antibiotics are also negatively affected by the mineral. If you’re taking any of these medications, talk to a healthcare practitioner for a plan to improve your calcium status.

No matter your health condition, following medical advice is crucial when beginning a supplement regimen. Getting too much calcium (called hypercalcemia) can be dangerous. And long-term use of supplements, even at safe doses, may result in an increased risk of kidney stones. 

One study looked at the effects of calcium supplements or placebo in postmenopausal women. Those who took the supplement had a higher risk of kidney stones. And, though their hip bone density increased, they did not have a lower risk of hip fractures. Although exact numbers differ, experts generally agree that the risk increases once the recommended daily amount is passed (Jackson, 2006).

High calcium intake may be linked to other serious conditions as well, including prostate cancer and heart disease.

Symptoms of hypercalcemia may also include fatigue, weakness, nausea, and vomiting, increased thirst, and/or confusion. If the condition gets severe enough, it may cause kidney stones, irregular heartbeat, heart attack, or coma.

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Current version

December 08, 2019

Written by

Linnea Zielinski

Fact checked by

Mike Bohl, MD, MPH, ALM

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About the medical reviewer

Mike Bohl, MD, MPH, ALM

Dr. Mike is a licensed physician and a former Director, Medical Content & Education at Ro.