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Should You Take Calcium Supplements?

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By Kerri-Ann Jennings

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).

Many people take calcium supplements hoping to strengthen their bones.Shutterstock

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. More than 99 percent 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.

Bottom Line: Your body uses calcium to build strong bones, send nerve signals and contract muscles. While it's possible to get enough of it in your diet, some people might need to consider 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.

Bottom Line: Calcium supplements may benefit those who are not getting enough calcium from food and women who have reached menopause.

The Benefits of Calcium Supplements

Calcium supplements may have several health benefits.

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 percent (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 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 helps calcium function.

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 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).

Bottom Line: Studies have linked taking calcium supplements with a lower risk of colon cancer and blood pressure, as well as fat loss and increases in bone density.

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.

Over the past several years, researchers have published opposing findings on this link (1, 13, 14, 15, 16, 17, 18, 19, 20).

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 Have Been Linked to Prostate Cancer

High levels of calcium have been 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 have been 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.

Bottom Line: Calcium supplements may increase the risk of heart disease and prostate cancer, although the link is unclear. Extremely high levels of calcium from any source may have negative health effects.

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).

Medication Interactions

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).

Bottom Line: When you're taking calcium supplements, it's important to consider the type, amount and whether they may interact with other medications you take.

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.

Calcium Carbonate

This is the cheapest and most widely available form. It contains 40 percent 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).

Calcium Citrate

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).

Bottom Line: The two main forms of calcium supplements are calcium carbonate and calcium citrate. Calcium carbonate needs to be taken with food and is less effective if you have low levels of stomach acid.

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
  • Beans and lentils
  • Fortified foods and drinks

Bottom Line: You can get all the calcium you need each day from food. Calcium-rich foods include yogurt, certain leafy greens, tofu and canned fish.

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.

Reposted with permission from our media associate Authority Nutrition.

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Given the present circumstances, Norway does not have either the legal or the technical basis for making its annual contribution to the Amazon Fund.

Brazilian President Jair Bolsonaro reacted with sarcasm to Norway's decision, which had been widely expected. After an official event, he commented: "Isn't Norway the country that kills whales at the North Pole? Doesn't it also produce oil? It has no basis for telling us what to do. It should give the money to Angela Merkel [the German Chancellor] to reforest Germany."

According to its website, the Amazon Fund is a "REDD+ mechanism created to raise donations for non-reimbursable investments in efforts to prevent, monitor and combat deforestation, as well as to promote the preservation and sustainable use in the Brazilian Amazon." The bulk of funding comes from Norway and Germany.

The annual transfer of funds from developed world donors to the Amazon Fund depends on a report from the Fund's technical committee. This committee meets after the National Institute of Space Research, which gathers official Amazon deforestation data, publishes its annual report with the definitive figures for deforestation in the previous year.

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An Uncertain Future

The Amazon Fund was announced during the 2007 United Nations Climate Change Conference in Bali, during a period when environmentalists were alarmed at the rocketing rate of deforestation in the Brazilian Amazon. It was created as a way of encouraging Brazil to continue bringing down the rate of forest conversion to pastures and croplands.

Government agencies, such as IBAMA, Brazil's environmental agency, and NGOs shared Amazon Fund donations. IBAMA used the money primarily to enforce deforestation laws, while the NGOs oversaw projects to support sustainable communities and livelihoods in the Amazon.

There has been some controversy as to whether the Fund has actually achieved its goals: in the three years before the deal, the rate of deforestation fell dramatically but, after money from the Fund started pouring into the Amazon, the rate remained fairly stationary until 2014, when it began to rise once again. But, in general, the international donors have been pleased with the Fund's performance, and until the Bolsonaro government came to office, the program was expected to continue indefinitely.

Norway has been the main donor (94 percent) to the Amazon Fund, followed by Germany (5 percent), and Brazil's state-owned oil company, Petrobrás (1 percent). Over the past 11 years, the Norwegians have made, by far, the biggest contribution: R$3.2 billion ($855 million) out of the total of R$3.4 billion ($903 million).

Up till now the Fund has approved 103 projects, with the dispersal of R$1.8 billion ($478 million). These projects will not be affected by Norway's funding freeze because the donors have already provided the funding and the Brazilian Development Bank is contractually obliged to disburse the money until the end of the projects. But there are another 54 projects, currently being analyzed, whose future is far less secure.

One of the projects left stranded by the dissolution of the Fund's committees is Projeto Frutificar, which should be a three-year project, with a budget of R$29 million ($7.3 million), for the production of açai and cacao by 1,000 small-scale farmers in the states of Amapá and Pará. The project was drawn up by the Brazilian NGO IPAM (Institute of Environmental research in Amazonia).

Paulo Moutinho, an IPAM researcher, told Globo newspaper: "Our program was ready to go when the [Brazilian] government asked for changes in the Fund. It's now stuck in the BNDES. Without funding from Norway, we don't know what will happen to it."

Norway is not the only European nation to be reconsidering the way it funds environmental projects in Brazil. Germany has many environmental projects in the Latin American country, apart from its small contribution to the Amazon Fund, and is deeply concerned about the way the rate of deforestation has been soaring this year.

The German environment ministry told Mongabay that its minister, Svenja Schulze, had decided to put financial support for forest and biodiversity projects in Brazil on hold, with €35 million ($39 million) for various projects now frozen.

The ministry explained why: "The Brazilian government's policy in the Amazon raises doubts whether a consistent reduction in deforestation rates is still being pursued. Only when clarity is restored, can project collaboration be continued."

Bauxite mines in Paragominas, Brazil. The Bolsonaro administration is urging new laws that would allow large-scale mining within Brazil's indigenous reserves.

Hydro / Halvor Molland / Flickr

Alternative Amazon Funding

Although there will certainly be disruption in the short-term as a result of the paralysis in the Amazon Fund, the governors of Brazil's Amazon states, which rely on international funding for their environmental projects, are already scrambling to create alternative channels.

In a press release issued yesterday Helder Barbalho, the governor of Pará, the state with the highest number of projects financed by the Fund, said that he will do all he can to maintain and increase his state partnership with Norway.

Barbalho had announced earlier that his state would be receiving €12.5 million ($11.1 million) to run deforestation monitoring centers in five regions of Pará. Barbalho said: "The state governments' monitoring systems are recording a high level of deforestation in Pará, as in the other Amazon states. The money will be made available to those who want to help [the Pará government reduce deforestation] without this being seen as international intervention."

Amazonas state has funding partnerships with Germany and is negotiating deals with France. "I am talking with countries, mainly European, that are interested in investing in projects in the Amazon," said Amazonas governor Wilson Miranda Lima. "It is important to look at Amazônia, not only from the point of view of conservation, but also — and this is even more important — from the point of view of its citizens. It's impossible to preserve Amazônia if its inhabitants are poor."

Signing of the EU-Mercusor Latin American trading agreement earlier this year. The pact still needs to be ratified.

Council of Hemispheric Affairs

Looming International Difficulties

The Bolsonaro government's perceived reluctance to take effective measures to curb deforestation may in the longer-term lead to a far more serious problem than the paralysis of the Amazon Fund.

In June, the European Union and Mercosur, the South American trade bloc, reached an agreement to create the largest trading bloc in the world. If all goes ahead as planned, the pact would account for a quarter of the world's economy, involving 780 million people, and remove import tariffs on 90 percent of the goods traded between the two blocs. The Brazilian government has predicted that the deal will lead to an increase of almost $100 billion in Brazilian exports, particularly agricultural products, by 2035.

But the huge surge this year in Amazon deforestation is leading some European countries to think twice about ratifying the deal. In an interview with Mongabay, the German environment ministry made it very clear that Germany is very worried about events in the Amazon: "We are deeply concerned given the pace of destruction in Brazil … The Amazon Forest is vital for the atmospheric circulation and considered as one of the tipping points of the climate system."

The ministry stated that, for the trade deal to go ahead, Brazil must carry out its commitment under the Paris Climate agreement to reduce its greenhouse gas emissions by 43 percent below the 2005 level by 2030. The German environment ministry said: If the trade deal is to go ahead, "It is necessary that Brazil is effectively implementing its climate change objectives adopted under the [Paris] Agreement. It is precisely this commitment that is expressly confirmed in the text of the EU-Mercosur Free Trade Agreement."

Blairo Maggi, Brazil agriculture minister under the Temer administration, and a major shareholder in Amaggi, the largest Brazilian-owned commodities trading company, has said very little in public since Bolsonaro came to power; he's been "in a voluntary retreat," as he puts it. But Maggi is so concerned about the damage Bolsonaro's off the cuff remarks and policies are doing to international relationships he decided to speak out earlier this week.

Former Brazil Agriculture Minister Blairo Maggi, who has broken a self-imposed silence to criticize the Bolsonaro government, saying that its rhetoric and policies could threaten Brazil's international commodities trade.

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Maggi, a ruralista who strongly supports agribusiness, told the newspaper, Valor Econômico, that, even if the European Union doesn't get to the point of tearing up a deal that has taken 20 years to negotiate, there could be long delays. "These environmental confusions could create a situation in which the EU says that Brazil isn't sticking to the rules." Maggi speculated. "France doesn't want the deal and perhaps it is taking advantage of the situation to tear it up. Or the deal could take much longer to ratify — three, five years."

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