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Calcium: What You Need to Know

Last Updated July 2023 | This article was created by editorial staff and reviewed by Kyle Bradford Jones, MD, FAAFP

Calcium is a mineral in your body that is also found in many foods. Most of the calcium in your body is in your bones and teeth. There is also calcium in your blood, muscles, other body tissues, and the fluid between your cells.

Path to improved health

You need calcium to keep your bones and teeth healthy and strong throughout your life. Your body also uses calcium to:

  • Help blood vessels and muscles work properly
  • Help release hormones and enzymes that keep your body working properly
  • Help your nerves carry messages throughout your body
  • Help control important nutrients, such as magnesium, phosphorus, and potassium

Your body can’t make more calcium. So, it’s important for you to provide it with the calcium it needs. The amount of calcium you need each day depends on your age, your sex, and other factors. For example, vitamin D improves calcium absorption. Alcohol reduces calcium absorption.

Doctors recommend:

  • Children ages 0-6 months: 200 milligrams (mg) per day
  • Children ages 7-12 months: 260 mg per day
  • Children ages 1-3: 700 mg per day
  • Children ages 4-8: 1,000 mg per day
  • Children ages 9-13: 1,300 mg per day
  • Teens ages 14-18: 1,300 mg per day
  • Adults ages 19-50: 1,000 mg per day
  • Adult men ages 51-70: 1,000 mg per day
  • Adult women ages 51-70: 1,200 mg per day
  • Adults ages 71 and older: 1,200 mg per day
  • Pregnant and breastfeeding teens: 1,300 mg per day
  • Pregnant and breastfeeding adults: 1,000 mg per day

Dietary sources of calcium

It’s best to spread your calcium throughout the day. Eat calcium-rich foods at every meal rather than all at once. Be sure to get enough vitamin D each day to help your body absorb the calcium.

Nonfat and low-fat dairy products (yogurt, cheese, and milk) are good sources of calcium. Vegetable sources of calcium include dried beans, kale, spinach, and collard greens. Animal sources of calcium include fish with soft bones, such as sardines and salmon. For example, 2 ounces of nonfat American cheese has 447 mg of calcium. One cup of skim milk has 299 mg of calcium. And 3 ounces of pink salmon has 183 mg of calcium. Some foods may be fortified with calcium (orange juice, bread, pasta, dry breakfast cereal, and dairy substitutes).

Calcium supplements

If you’re not getting enough calcium from dietary sources, talk to your doctor about a calcium supplement. Depending on your age, sex, overall health, and other factors, your doctor might recommend that you take a calcium supplement. Also, your doctor can tell you if a calcium supplement will affect any medical conditions you have. They will need to know about any prescription or over-the-counter (OTC) medicines, or other dietary supplements you are taking.

It’s important to know that calcium supplements can affect the way certain other medicines you are taking work. For example, calcium supplements can interfere with blood pressure and synthetic thyroid medicines, bisphosphonates, and antibiotics as well as certain medicines prescribed to treat bipolar disorder and HIV. Other supplements, such as iron, can affect how the body absorbs, uses, or gets rid of medicines or supplements.

There are 2 main types of calcium supplements: calcium carbonate and calcium citrate. Both types are available without a prescription. Over-the-counter calcium supplements are available in tablet, chewable, liquid, and powder form. Other types of calcium include calcium gluconate and calcium lactate. These contain less elemental calcium than calcium carbonate and calcium citrate.

If a supplement is right for you, your doctor will help you decide which one to take. They will also explain what amount of calcium to take each day and how to take the supplement. For example, calcium carbonate should be taken with meals to avoid possible unpleasant health effects (also called adverse effects). Taking it with meals helps your body to better absorb it. Calcium citrate can be taken on an empty stomach.

Things to consider

If your body doesn’t get enough calcium and vitamin D to support important functions, it takes calcium from your bones. This is called losing bone mass. Losing bone mass makes the inside of your bones become weak and porous. This puts you at risk for the bone disease osteoporosis.

Certain populations are at higher risk for low calcium levels, including:

Unfortunately, getting more calcium than your body needs can cause adverse (negative) effects. This includes kidney stones, frequent urination, belly pain, nausea/vomiting, and fatigue. It is rare to get too much calcium from food alone. There is an amount of calcium that most people can take each day without developing problems. This is called the tolerable upper intake level. Doctors recommend the following tolerable upper intake levels by age:

  • Ages 0-6 months: 1,000 mg per day
  • Ages 7-12 months: 1,500 mg per day
  • Ages 1-8: 2,500 mg per day
  • Ages 9-18: 3,000 mg per day
  • Ages 19-50: 2,500 mg per day
  • Ages 51 and older: 2,000 mg per day
  • Pregnant and breastfeeding teens: 3,000 mg per day
  • Pregnant and breastfeeding adults: 2,500 mg per day

In addition, research shows that high intakes of calcium may provide health benefits in lowering the risk of colon cancer, preeclampsia (pregnancy related complication), and metabolic syndrome (such as diabetes). Other research shows that high calcium intake may raise the risk of prostate cancer. Conflicting research suggests that a high intake of calcium may or may not provide a protection against heart disease.

Talk to your doctor about whether supplements are right for you.

Questions to ask your doctor

  • Can too much calcium upset your stomach?
  • Can illness cause low calcium?
  • Can you develop osteoporosis at an early age?


National Institutes of Health: Calcium and Vitamin D: Important at Every Age

National Institutes of Health, Office of Dietary Supplements: Calcium

U.S. National Library of Medicine, MedlinePlus: Calcium

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