Calcium: What You Need to Know Family Doctor Logo

Calcium: What You Need to Know

What is calcium?

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.

Why is calcium so important to my 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 high levels of magnesium, phosphorus, and potassium in the blood

How much calcium do I need each day?

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 intake improves calcium absorption, while alcohol consumption reduces calcium absorption). The Food and Nutrition Board at the Institute of Medicine of the National Academies recommends the following daily intake of calcium by age.

Recommended Dietary Allowance (RDA) for Calcium
AgeRDA per day in milligrams (mg)
0-6 months200 mg
7-12 months260 mg
1-3 years700 mg
4-8 years1,000 mg
9-13 years1,300 mg
14-18 years1,300 mg
19-50 years1,000 mg
51-70 years (men)1,000 mg
51-70 years (women)1,200 mg
71+ years1,200 mg

It is best to get your calcium throughout the day (for example, by eating calcium-rich foods at every meal) rather than all at once. You should also be sure to get enough vitamin D each day to help your body absorb the calcium. Calcium and vitamin D work together.

What happens if I don’t get enough calcium and vitamin D?

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. Over time, losing bone mass makes the inside of your bones become weak and porous, which can put you at risk for osteoporosis.

The following groups are at higher risk for low calcium levels:

  • Girls 9 to 18 years of age
  • Boys 9 to 13 years of age
  • Postmenopausal women
  • People who have lactose intolerance and avoid dairy products
  • Women who have an eating disorder (for example, anorexia or the female athlete triad)
  • People who do not eat animal, fish, or dairy products (vegans)
  • People who take certain medicines for osteoporosis
  • People who have parathyroid disorders, inflammatory bowel disease, or liver or kidney disease

What foods and drinks are good sources of calcium?

It’s best to try to get the calcium your body needs from dietary sources (foods and drinks). Nonfat and low-fat dairy products (for example, 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. Some foods may be fortified with calcium (for example, orange juice, bread, pasta, dry breakfast cereal, and dairy substitutes).

The following are some foods and drinks that are good sources of calcium:

Dietary Source Serving Size Amount of Calcium in Milligrams (mg)
Nonfat or fat-free American cheese2 ounces447 mg
Nonfat or low-fat yogurt8 ounces415 mg
Sardines3 ounces325 mg
Low-fat 1% milk1 cup314 mg
Skim milk1 cup299 mg
Collard greens1 cup cooked268 mg
Whole ground sesame seeds3 tablespoons263 mg
Soybeans, raw1/2 cup252 mg
White beans, raw1/2 cup242 mg
Enriched soy, almond, or rice milk1 cup200 to 300 mg
Fortified oatmeal, dry2 ounces197 mg
Spinach1 cup cooked194 mg
Pink salmon3 ounces183 mg
Ocean perch3 ounces116 mg
Figs5 figs112 mg
Almonds1/4 cup96 mg

What about calcium supplements?

If you’re worried that you are not getting enough calcium from dietary sources, talk to your family doctor. Depending on your age, sex, overall health, and other factors, your doctor might recommend that you take a calcium supplement.

Your doctor can tell you if a calcium supplement will affect any medical conditions you have. He or she also needs to know about any prescription or over-the-counter (OTC) medicines, or other dietary supplements you are taking. Calcium supplements can affect the way certain medicines (for example, blood pressure medicines, synthetic thyroid, bisphosphonates, and antibiotics) and other supplements (for example, iron supplements) act, or the way that the body absorbs, uses, or gets rid of medicines or supplements.

What types of calcium supplements are available?

There are two main types of calcium supplements: calcium carbonate and calcium citrate. Both types are available without a prescription from your doctor and can help you get enough calcium. You can get OTC calcium supplements in a variety of forms, including tablets, chews, liquids, and powders.

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 what type of calcium supplement to take. He or she 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). Calcium citrate can be taken on an empty stomach.

How much calcium is too much?

Getting more calcium than your body needs can cause adverse effects, such as kidney stones, frequent urination, belly pain, nausea/vomiting, and fatigue. It is rare to get too much calcium from dietary sources alone. Be sure to talk to your doctor about whether supplements are right for you.

The tolerable upper intake level of calcium is the greatest amount of calcium that most people can take each day without having adverse effects. The Food and Nutrition Board recommends the following tolerable upper intake levels by age.

Tolerable Upper Intake Levels (ULs) for Calcium
AgeULs per day in milligrams (mg)
0-6 months1,000 mg
7-12 months1,500 mg
1-8 years2,500 mg
9-18 years3,000 mg
19-50 years2,500 mg
51+ years2,000 mg

This content was updated with general underwriting support from NatureMade®. Funding and support for this material have been provided by the Consumer Healthcare Products Association.