Medically reviewed by Kathy W. Warwick, R.D., CDE, Nutrition — Written by Tim Newman on January 28, 2020

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Calcium is a nutrient that all living organisms need, including humans. It is the most abundant mineral in the body, and it is vital for bone health.

Humans need calcium to lớn build & maintain strong bones, and 99% of the body’s calcium is in the bones and teeth. It is also necessary for maintaining healthy communication between the brain và other parts of the body. It plays a role in muscle movement và cardiovascular function.

Calcium occurs naturally in many foods, and food manufacturers add it khổng lồ certain products. Supplements are also available.

Alongside calcium, people also need vitamin D, as this vitamin helps the toàn thân absorb calcium. Vitamin D comes from fish oil, fortified dairy products, & exposure lớn sunlight.

This article looks at why the body needs calcium, which foods are rich in calcium, what happens if the toàn thân does not have enough, & the pros và cons of taking supplements.

Why we need calcium

Share on PinterestGreen leafy vegetables, such as broccoli, are a good source of calcium.

Calcium plays various roles in the body. These include the following:

Bone health

Around 99% of the calcium in the human body is in the bones và teeth. Calcium is essential for the development, growth, & maintenance of bone.

As children grow, calcium contributes to the development of their bones. After a person stops growing, calcium continues lớn help maintain the bones và slow down bone density loss, which is a natural part of the aging process.

Females who have already experienced menopause can thua thảm bone density at a higher rate than males or younger people. They have a higher risk of developing osteoporosis, and a doctor may recommend calcium supplements.

Learn more here about osteoporosis.

Muscle contraction

Calcium helps regulate muscle contraction. When a nerve stimulates a muscle, the body toàn thân releases calcium. The calcium helps the proteins in muscle carry out the work of contraction.

When the body toàn thân pumps the calcium out of the muscle, the muscle will relax.

Cardiovascular system

Calcium plays a key role in blood clotting. The process of clotting is complex and has a number of steps. These involve a range of chemicals, including calcium.

Calcium’s role in muscle function includes maintaining the action of the heart muscle. Calcium relaxes the smooth muscle that surrounds blood vessels. Various studies have indicated a possible liên kết between high consumption of calcium & lower blood pressure.

Vitamin D is also essential for bone health, & it helps the body absorb calcium. Find out more about vi-ta-min D & why we need it.

Other roles

Calcium is a co-factor for many enzymes. Without calcium, some key enzymes cannot work efficiently.

Studies have also suggested that consuming enough calcium can result in:

lower blood pressure in young peoplelower blood pressure in those whose mothers who consumed enough calcium during pregnancy

Find out more here about the effects of having low calcium levels.

People can obtain calcium from a range of foods & drinks.

The following are good sources:

yogurtmilkfortified dairy alternatives, such as soy milksardines và salmoncheesetofumany fortified breakfast cerealsfortified fruit juicesnuts và seeds, especially almonds, sesame, and chialegumes và grainscornmeal & corn tortillas

Some dark green vegetables, such as spinach, contain calcium. However, they also contain high levels of oxalic acid. Oxalic acid reduces the body’s ability to absorb calcium, according to lớn studies.

Click here for some tips on getting enough calcium on a plant-based diet.

The following conditions or lifestyle habits may result in low calcium levels, also known as hypocalcemia:

mercury exposurelong-term use of laxativeschelation therapy used for metal exposurelack of parathyroid hormonepeople who eat a lot of protein or sodium may excrete calcium.high consumption of caffeine, soda, or alcoholsome surgical procedures, including removing the stomachkidney failurevitamin D deficiencyphosphate deficiency

The toàn thân eliminates some calcium in sweat, urine, & feces. Foods & activities that encourage these functions may reduce the levels of calcium in the body.

A doctor may recommend calcium supplements for people who have a calcium deficiency.

People who use calcium supplements should:

check first with their doctor whether they need supplementsfollow the dosage the doctor recommendstake the supplement with food for best absorption & to minimize possible adverse effectsconsume the supplements at intervals, usually two or three times a day

According to the ODS, around 43% of all adults in the United States take calcium supplements, including 70% of older females. Taking supplements can increase daily calcium intake by about 300 mg of calcium a day, on average.

Many calcium supplements also contain vitamin D. Vi-ta-min D encourages the synthesis of proteins in the toàn thân and helps the body toàn thân absorb calcium. Magnesium also plays a role in strengthening bones, and calcium supplements may also contain magnesium.

Types of supplement

There are different types of supplements. A doctor can recommend the best option. This will depend on the individual’s needs and preferences, any medical conditions they have, and whether they are taking any medications.

Elemental calcium is the pure mineral, but calcium in its natural khung exists with other compounds.

Supplements may contain different proportions of calcium compounds and elemental calcium. For example:

Calcium carbonate: This contains 40% elemental calcium. This type is commonly available, và it is relatively cheap and convenient. A person should take it with food, as stomach acid helps the body absorb it.

Calcium lactate: This contains 13% elemental calcium.

Calcium gluconate: This contains 9% elemental calcium.

Calcium citrate: This contains 21% elemental calcium. A person can take it with or without food. It is useful for people with inflammatory bowel disease, achlorhydria, and some absorption disorders.

Research has found conflicting evidence regarding the benefits & drawbacks of supplement use.

Most experts agree that it is better khổng lồ obtain nutrients from natural food sources, although sometimes it is not possible to get enough in this way.

Some studies have suggested, however, that calcium supplementation could be hazardous.

Side effects

Some people report gastrointestinal symptoms, such as bloating, constipation, gas, or a combination of all three when using calcium supplements.

Calcium citrate usually has fewer and less pronounced side effects than calcium carbonate. Taking the supplements with food, or spreading their intake throughout the day may help reduce the occurrence or intensity of the side effects.


Very high levels of calcium can lead to:

kidney problemscalcification of soft tissues & blood vesselsconstipation

Although high calcium levels due khổng lồ taking too many supplements might cause these severe side effects, they are more likely the result of cancer and thyroid problems, according to the ODS.

Possible complications

Past studies have raised concerns that taking calcium supplements may increase the risk of:

kidney stonesa reduction in iron absorption

However, more recent studies have suggested that these concerns may be unfounded.

Calcium may interact with some drugs. Experts make the following recommendations:

Avoid supplement use while taking calcium channel blockers, which are a common type of medication for lowering blood pressure.

Calcium is essential for building & maintaining healthy bones & teeth. Among other roles, it may also help manage blood pressure.

It is best khổng lồ obtain sufficient calcium through dietary sources, such as dairy products, green leafy vegetables, và tofu. However, a doctor may recommend supplementation for some people.

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Due lớn individual differences in requirements, experts vì chưng not recommend calcium supplementation for everyone. Anyone who is considering taking supplements should ask their healthcare provider for advice.