Many people take calcium supplements hoping to strengthen their bones.
However, they may have drawbacks and even health risks, including raising the risk of heart disease (1).
This article explains what you need to know about calcium supplements, including who should take them, their health benefits and potential risks.
Why Do You Need Calcium?
Your body needs calcium to build and maintain strong bones. Over 99% of the calcium in your body is stored in your bones and teeth (2).
In the bloodstream, it’s used to send nerve signals, release hormones like insulin and regulate how muscles and blood vessels contract and dilate (2).
It’s so important that if you don’t get the recommended amount in your diet, your body will take it from your skeleton and teeth to use elsewhere, weakening your bones.
So how much calcium do you need each day?
Below are the current recommendations from the Institute of Medicine, by age (2):
- Women 50 and younger: 1,000 mg per day
- Men 70 and younger: 1,000 mg per day
- Women over 50: 1,200 mg per day
- Men over 70: 1,200 mg per day
There are also recommended upper limits for calcium intake. The cap is 2,500 mg per day for adults up to age 50 and 2,000 mg per day for adults over 50 (2).
It’s possible to get sufficient amounts through your diet. Foods that contain it include dairy products, certain leafy greens, nuts, beans and tofu.
However, people who don’t eat enough calcium-rich foods might consider taking supplements.
Who Should Take Calcium Supplements?
When your calcium intake is insufficient, your body will remove calcium from your bones, making them weak and brittle. This can result in osteoporosis.
Since women are at a higher risk of osteoporosis, many doctors recommend that they take calcium supplements, especially after reaching menopause.
Because of this, older women are much more likely to take calcium supplements (2).
If you don’t get the recommended amount through your diet, supplements can help fill the gap.
You might also consider calcium supplements if you:
- Follow a vegan diet.
- Have a high-protein or high-sodium diet, which may cause your body to excrete more calcium.
- Have a health condition that limits your body’s ability to absorb calcium, such as Crohn’s disease or inflammatory bowel disease.
- Are being treated with corticosteroids over a long period of time.
- Have osteoporosis.
They May Help Prevent Bone Loss in Postmenopausal Women
After menopause, women lose bone mass due to a decline in estrogen.
Luckily, supplements may help. Several studies have suggested that giving postmenopausal women calcium supplements — usually around 1,000 mg per day — may reduce bone loss by 1–2% (3).
The effect seems to be greatest in women with low calcium intakes and during the first two years of taking supplements.
Plus, there doesn’t seem to be any additional benefit to taking larger doses (4).
They May Help With Fat Loss
Studies have associated low calcium intake with a high body mass index (BMI) and high body fat percentage (5).
A 2016 study examined the effects of giving a daily 600-mg calcium supplement to overweight and obese college students with very low calcium intakes.
The study found that those given a supplement containing 600 mg of calcium and 125 IUs of vitamin D lost more body fat on a calorie-restricted diet than those who did not receive the supplement (6).
It’s often recommended to take vitamin D with calcium, since it improves its absorption.
Calcium May Help Lower the Risk of Colon Cancer
According to one large study, calcium from dairy products and supplements may lower the risk of colon cancer (7).
An earlier review of 10 studies found similar results (8).
Supplements May Help Improve Metabolic Markers
Several studies have suggested that taking calcium supplements might improve metabolic markers, especially when taken with vitamin D.
In a 2016 study, 42 pregnant women took supplements containing calcium and vitamin D. Several of their metabolic markers improved, including blood pressure and markers of inflammation (9).
Other research has shown that the children of women who took calcium supplements while pregnant have lower blood pressure at age seven than the children of mothers who did not take them (10).
In a recent study, more than 100 overweight, vitamin D-deficient women with polycystic ovary syndrome (PCOS) were given either a calcium and vitamin D supplement or placebo pill.
Those who took the supplement showed improvements in markers of inflammation, insulin and triglyceride levels (11, 12).
However, other studies have shown no improvements in the metabolic profiles of dieters who took supplements containing both calcium and vitamin D (6).
Possible Dangers of Calcium Supplements
Recent research suggests that calcium supplements may, in fact, cause some health problems. However, the evidence is mixed.
They May Increase Risk of Heart Disease
Perhaps the most controversial suggestion about calcium supplements is that they may increase the risk of some types of heart disease, including heart attack and stroke.
More conclusive research is needed to determine the effect of calcium supplements on heart health.
Some experts have suggested that taking calcium with vitamin D may neutralize the possible risks, but this needs to be studied more (14, 15).
High Levels May Be Linked to Prostate Cancer
High levels of calcium may be linked to prostate cancer, although the research on this link is also conflicting.
In several studies, most of which were observational, researchers found that high intakes of calcium may be linked to an increased risk of prostate cancer (21, 22, 23, 24, 25).
However, a randomized controlled study that gave 672 men either a calcium supplement or placebo every day for four years showed that participants did not have an increased risk of prostate cancer.
In fact, participants who took the supplement had fewer cases of prostate cancer (21).
Other research has suggested that dairy products may be the culprit. A review of 32 articles reported that consuming dairy products — but not calcium supplements — was linked to an increased risk of prostate cancer (26).
Risk of Kidney Stones May Increase
There is some evidence that calcium supplements increase the risk of kidney stones.
One study gave more than 36,000 postmenopausal women either a daily supplement containing 1,000 mg of calcium and 400 IU of vitamin D or a placebo pill.
The results showed that those who took the supplement had an increased risk of kidney stones (27).
Furthermore, while supplement users in the study experienced an overall increase in hip bone density, they didn’t have a lower risk of hip fractures.
Consuming more than 2,000 mg of calcium a day from your diet or supplements is also linked to an increased risk of kidney stones, according to the Institute of Medicine (2).
Other sources say that the risk of kidney stones increases when calcium intake exceeds 1,200–1,500 mg per day (28).
High Levels of Calcium in Your Blood
Having too much calcium in your blood leads to a condition called hypercalcemia, which is characterized by many negative symptoms, including stomach pain, nausea, irritability and depression.
It can be caused by several things, including dehydration, thyroid conditions and taking high levels of calcium supplements.
Excessive vitamin D supplements may also lead to hypercalcemia by encouraging your body to absorb more calcium from your diet.
Things to Consider When Taking Calcium Supplements
If you take calcium supplements, there are several factors you should be aware of.
How Much Should You Take?
Calcium supplements can help fill the gap between how much calcium you get in your diet and how much you need per day.
Remember, the recommended amount for most adults is 1,000 mg per day and increases to 1,200 mg per day for women over 50 and men over 70.
Therefore, if you typically only get around 500 mg per day through food and need 1,000 mg per day, then you can take one 500-mg supplement daily (28).
However, choose your dose wisely. Taking in more calcium than you need can cause problems (29).
You May Need to Split up the Dose
It’s important to check the amount of calcium in the supplement you choose.
Your body can’t absorb large doses of it at once. Experts recommend taking no more than 500 mg at a time in supplement form (1).
Make sure to tell your doctor and pharmacist if you are taking calcium supplements, since they can interfere with how your body processes certain medications, including antibiotics and iron.
Calcium also competes with iron, zinc and magnesium for absorption. If you are deficient in any of those minerals and also need to take calcium supplements, try taking them between meals (30).
This way the calcium is less likely to inhibit the absorption of the zinc, iron and magnesium that you consume in your meal.
Dangers of Too Much Calcium
Remember, you only need 1,000–1,200 mg of calcium each day. There’s no benefit to taking more than that. In fact, you could experience problems if you do.
Problems include constipation, hypercalcemia, calcium buildup in soft tissues and trouble absorbing iron and zinc (2).
Different Types of Calcium Supplements
Calcium supplements come in different forms, including tablets, capsules, chews, liquids and powders.
One key difference between these types of supplements is the form of calcium they contain.
The two main forms are:
- Calcium carbonate
- Calcium citrate
These two forms differ in how much elemental calcium they contain and how well they’re absorbed. Elemental calcium refers to the amount of calcium that is present in the compound.
This is the cheapest and most widely available form. It contains 40% elemental calcium and therefore usually delivers a lot of calcium in a small serving.
However, this form is more likely to cause side effects, such as gas, bloating and constipation. It is recommended that calcium carbonate be taken with food for optimal absorption (30).
This form is more expensive. Twenty-one percent of it is elemental calcium, meaning you may need to take more tablets to get the amount of calcium you need.
However, it’s more easily absorbed than calcium carbonate and can be taken with or without food.
Calcium citrate is the form recommended for people with irritable bowel syndrome.
It’s also the better choice for those with low levels of stomach acid, a condition common among older people and those taking medications for acid reflux (30).
Food Sources of Calcium
It’s best to get nutrients from food rather than supplements.
Nevertheless, if you think you’re not getting enough calcium in your diet, consider eating more of these foods:
- Dairy, including milk, cheese and yogurt
- Canned fish with bones, such as salmon or sardines
- Certain leafy greens including collard greens, spinach and kale
- Edamame and tofu
- Beans and lentils
- Fortified foods and drinks
Take Home Message
Calcium supplements can help people who are at risk of osteoporosis, as well as those who don’t get enough calcium in their diets.
While some research suggests a link between calcium supplements and heart disease, the link is not clear.
However, it is known that getting more than the recommended amount of calcium from any source may raise your risk of kidney stones.
Calcium supplements are probably fine in small doses, but the best way to get calcium is from food. Strive to incorporate a variety of calcium-rich foods in your diet, including non-dairy sources.
Learn about unknown needs of your skin for free