Calcium is a nutrient that all living organisms, including humans, need. Dietary sources of calcium include dairy products, green leafy vegetables, nuts, seeds, and fortified products.
Calcium is the most abundant mineral in the body. Humans need calcium to build and maintain strong bones, and
of the body’s calcium is in the bones and teeth. It is also necessary to maintain healthy communication between the brain and other body parts. It plays a role in muscle movement and cardiovascular function.
Calcium occurs naturally in many foods, and food manufacturers add it to certain products. Supplements are also available.
Alongside calcium, people also need
, as this
helps the body absorb calcium. Vitamin D comes from
, fortified dairy products, and exposure to sunlight.
This article looks at why the body needs calcium, which foods are rich in calcium, what happens if the body does not have enough, and the pros and cons of taking supplements.
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 and teeth. Calcium is essential for the development, growth, and maintenance of bone.
As children grow, calcium contributes to the development of their bones. After a person stops growing, calcium continues to help maintain the bones and slow down bone density loss, which is a natural part of the aging process.
Females who have already experienced
can lose bone density at a higher rate than males or younger people. They have a higher risk of developing
, and a doctor may recommend calcium supplements.
Learn more
about osteoporosis.
Muscle contraction
Calcium helps regulate muscle contraction. When a nerve stimulates a muscle, the body releases calcium. The calcium helps the proteins in muscle carry out the work of contraction.
When the body 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
maintaining the action of the heart muscle. It also relaxes the smooth muscle that surrounds blood vessels. Various studies have indicated a possible link between high calcium consumption and lower
.
Vitamin D is also essential for bone health, and it helps the body absorb calcium.
about vitamin D and 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:
a lower risk of developing conditions involving
during pregnancy
lower blood pressure in young people
lower blood pressure in those whose mothers consumed enough calcium during pregnancy
improved
values
a lower risk of colorectal adenomas, a type of noncancerous
Find out more
about the effects of having low calcium levels.
People can obtain calcium from a range of foods and drinks.
The following are good
:
yogurt
milk
fortified dairy alternatives, such as soy milk
sardines and salmon
cheese
tofu
green leafy vegetables, such as broccoli, turnip leaves, watercress, and
many fortified breakfast cereals
fortified fruit juices
nuts and seeds, especially almonds, sesame, and chia
legumes and grains
cornmeal and 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
.
Click
for some tips on getting enough calcium on a plant-based diet.
0–6 months: 200 milligrams (mg)
7–12 months: 260 mg
1–3 years: 700 mg
4–8 years: 1,000 mg
9–18 years: 1,300 mg
19–50 years: 1,000 mg
51–70 years: 1,000 mg for males and 1,200 mg for females
71 years and above: 1,200 mg
Pregnant and breastfeeding women require 1,000–1,300 mg depending on age.
A doctor may recommend additional calcium for people who:
have started menopause
stop menstruating due to
or excessive exercise
have
or a cow’s milk allergy
follow a vegan diet
The following conditions or lifestyle habits may result in low calcium levels, also known as hypocalcemia:
, anorexia, and some other eating disorders.
mercury exposure
overconsumption of
long-term use of laxatives
prolonged use of some medications, such as
or corticosteroids
chelation therapy used for metal exposure
lack of parathyroid hormone
people who eat a lot of protein or sodium may excrete calcium.
some
high consumption of caffeine, soda, or alcohol
some conditions, such as
, inflammatory bowel disease,
, and some other digestive diseases
some surgical procedures, including removing the stomach
kidney failure
vitamin D deficiency
phosphate deficiency
The body eliminates some calcium in sweat, urine, and feces. Foods and activities that encourage these functions may reduce calcium levels 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 supplements
follow the dosage the doctor recommends
take the supplement with food for best absorption and to minimize possible adverse effects
consume the supplements at intervals, usually two or three times a day
According to the ODS, around
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. Vitamin D encourages the synthesis of proteins in the body and helps the body 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 form 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, and 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 and drawbacks of supplement use.
Most
agree that it is better to 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,
, 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.
Complications
Very high levels of calcium can lead to:
kidney problems
calcification of soft tissues and blood vessels
constipation
Although high calcium levels due to 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
of:
kidney stones
a reduction in iron absorption
a higher risk of a
However, more recent studies have suggested that these concerns may be unfounded.
Calcium may interact with some drugs. Experts make the following recommendations:
Take calcium supplements separately from some
.
Avoid supplement use while taking calcium channel blockers, a common medication for lowering blood pressure.
Calcium is essential for building and maintaining healthy bones and teeth. Among other roles, it may also help manage blood pressure.
Obtaining sufficient calcium through dietary sources, such as dairy products, green leafy vegetables, and tofu, is preferable overall. However, a doctor may recommend supplementation for some people.
Due to individual differences in requirements, experts do not recommend calcium supplementation for everyone. Anyone who is considering taking supplements should ask their healthcare professional for advice.