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Calcium
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Food Nutrition

Calcium

Calcium is a vital mineral that supports strong bones, muscle movement, nerve signaling, blood‑vessel function, and hormone release, and it must be obtained through diet or supplements to prevent deficiencies such as osteoporosis, rickets, and osteomalacia.

Overview

What is calcium and why do I need it?

Calcium is a mineral, a nutrient that you need (in small amounts) to keep your body healthy. You have more calcium in your body than any other mineral.

Calcium has many important jobs:

  • To build and maintain strong bones. Your body stores almost all of its calcium in your bones and teeth to keep them strong.
  • To help your muscles move.
  • To help your nerves to carry messages between your brain and the rest of your body.
  • To help your blood vessels move blood throughout your body.
  • To help release hormones that affect many functions in your body.

Not getting enough calcium can cause several conditions, including:

  • Osteoporosis, a disease which can make your bones weaker and more likely to break.
  • Rickets, a disease in children that causes soft, weak bones.
  • Osteomalacia, a condition which causes soft bones in children and adults.

How to Get Calcium

Food Sources

You can get calcium from foods and supplements. You may be able to get enough calcium by eating a variety of foods, including:

  • Dairy products such as milk, cheese, and yogurt. These are the main food sources of calcium for most people in the United States.
  • Leafy, green vegetables such as kale, broccoli, and Chinese cabbage (bok choi).
  • Fish with soft bones that you can eat, such as canned sardines and salmon.
  • Calcium‑enriched foods such as breakfast cereals, fruit juices, soy and rice drinks, and tofu. The product labels for these foods will show how much calcium they have.

Supplement Forms

Calcium is available in supplements. It is also included in many multivitamins. The two main forms of calcium supplements are calcium carbonate and calcium citrate:

  • Calcium carbonate is absorbed best when taken with food. Some over‑the‑counter antacids, such as Tums and Rolaids, also contain calcium carbonate.
  • Calcium citrate is absorbed well on an empty stomach or a full stomach. People with low levels of stomach acid absorb calcium citrate more easily than calcium carbonate.

Calcium is absorbed best when you take 500 mg or less at one time. If you are taking more than that amount each day, take a smaller dose twice a day rather than taking it all at once.

Calcium supplements might cause gas, bloating, and constipation in some people. If you have any of these symptoms, you could try:

  • Spreading out the calcium dose throughout the day
  • Taking it with meals
  • Switching the form of calcium you take

Recommended Intake

How much calcium do I need?

The amount of calcium you need each day depends on your age and other factors. The recommended amounts, in milligrams (mg), are:

  • Birth to 6 months: 200 mg
  • Infants 7‑12 months: 260 mg
  • Children 1‑3 years: 700 mg
  • Children 4‑8 years: 1,000 mg
  • Children 9‑13 years: 1,300 mg
  • Teens 14‑18 years: 1,300 mg
  • Adults 19‑50 years: 1,000 mg
  • Adult men 51‑70 years: 1,000 mg
  • Adult women 51‑70 years: 1,200 mg
  • Adults 71 years and older: 1,200 mg
  • Pregnant and breastfeeding teens: 1,300 mg
  • Pregnant and breastfeeding adults: 1,000 mg

Populations at Risk

Certain people may have trouble getting enough calcium, including:

  • Children and teens age 4 to 18 years
  • People who are Black or Asian
  • Adults age 50 years and older living in poverty
  • Postmenopausal women; your body absorbs and retains less calcium after menopause
  • People who don't drink milk or eat other dairy products

Check with your health care provider to see if you need to take calcium supplements, and if so, how much you should take. Your provider may want to first do a calcium blood test to see if you are getting enough of it.

Frequently Asked Questions

The daily recommended intake varies by age and sex. Most adults between ages 19 and 50 need about 1,000 milligrams per day. Women over 50 and men over 70 need 1,200 milligrams daily to help protect bone density. Teenagers need 1,300 milligrams because they are building peak bone mass, while infants and young children require smaller amounts, typically ranging from 200 to 700 milligrams depending on their specific age group. Can I take too much calcium, and what are the signs of an overdose?::Yes, consuming too much calcium can be harmful. The upper limit for most adults is 2,500 milligrams per day from all sources combined. Excessive intake can lead to kidney stones, constipation, and nausea. In severe cases, it may interfere with the absorption of other minerals like iron and zinc. If you are taking supplements, it is crucial to check the label and ensure you are not exceeding the recommended daily allowance when combined with dietary sources. What is the best way to absorb calcium from my diet, and are there foods that block it?::Calcium absorption is significantly improved when consumed with Vitamin D, which helps the body absorb the mineral from the gut. To maximize absorption, it is best to take calcium in smaller doses of 500 milligrams or less at a time, as the body cannot absorb large amounts efficiently in one sitting. High intakes of sodium and caffeine can increase calcium loss through urine, so moderating these can help maintain bone health. Additionally, oxalates found in spinach and rhubarb can bind to calcium and reduce its absorption, so pairing calcium-rich foods with low-oxalate options is beneficial. Do I need to take calcium supplements if I already eat a balanced diet?::For many people, a balanced diet rich in dairy products, leafy greens, and fortified foods is sufficient to meet calcium needs without supplements. However, individuals who are lactose intolerant, vegan, or have specific medical conditions that affect absorption may need to consider supplements. It is generally recommended to get calcium from food first, as it is absorbed more effectively and comes with other beneficial nutrients. If you choose to supplement, consult with a healthcare provider to determine the appropriate dosage and type, such as calcium carbonate or calcium citrate, based on your digestive health.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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