Calcium builds and maintains strong bones and teeth, and it also supports muscles, nerves and the heart. Many people do not get enough, and some take supplements without knowing the right type or timing. This guide covers daily calcium needs, food sources, who is at risk, supplement types, safe limits and medicine interactions, based on the NIH Office of Dietary Supplements consumer fact sheet.
How Much Calcium Do You Need Each Day?
The NIH lists these recommended daily amounts:
- Children 1 to 3 years: 700 mg
- Children 4 to 8 years: 1,000 mg
- Children and teens 9 to 18 years: 1,300 mg
- Adults 19 to 50 years: 1,000 mg
- Men 51 to 70 years: 1,000 mg; women 51 to 70 years: 1,200 mg
- Adults 71 years and older: 1,200 mg
- Pregnant and breastfeeding women: 1,000 mg (1,300 mg for teens)
Best Food Sources of Calcium
Check labels on fortified foods. Most grains are not high in calcium, but because people eat them often, they add up over the day.
- Milk, yogurt and cheese, the main sources for most people
- Canned sardines and salmon with bones
- Kale, broccoli and Chinese cabbage (bok choy)
- Calcium-fortified juices, soy and almond drinks, some tofu and some ready-to-eat cereals
Who Is at Risk of Getting Too Little Calcium?
- Children and teens aged 4 to 18
- Postmenopausal women
- People who do not drink milk or eat dairy, including those who are lactose intolerant, have a milk allergy or follow a vegan diet
Too little calcium over time can lead to osteoporosis, rickets in children and osteomalacia in adults.
Calcium and Vitamin D
Vitamin D helps your body absorb calcium, so the two work together for bone health. Read more in our guide to vitamin D daily needs and sources.
Calcium Supplements: Types and Tips
- Calcium carbonate is absorbed best with food. Many antacids contain it.
- Calcium citrate is absorbed well with or without food and suits people with low stomach acid.
- The body absorbs calcium best when you take 500 mg or less at one time.
- Supplements can cause gas, bloating and constipation.
Count calcium from food and drinks before adding a supplement, so you do not go over the upper limit.
How Much Calcium Is Too Much?
The upper limit is 2,500 mg a day for adults 19 to 50 years and 2,000 mg a day for adults 51 and older, from food, drinks and supplements together. Very high blood calcium can cause poor muscle tone, kidney problems, constipation, nausea, tiredness, frequent urination and abnormal heart rhythms. The NIH explains these are usually caused by a health condition rather than by high calcium intake, but some research suggests very high intakes might raise the risk of heart disease and prostate cancer.
Calcium and Medicine Interactions
- Levothyroxine is not absorbed well within 4 hours of a calcium carbonate supplement.
- Quinolone antibiotics such as ciprofloxacin are not absorbed well within 2 hours of a calcium supplement.
- Dolutegravir should be taken 2 hours before or 6 hours after calcium supplements.
- Lithium used long term, or together with calcium supplements, can cause abnormally high blood calcium.
Ask your pharmacist or doctor how to space your medicines and supplements.
Frequently Asked Questions
How much calcium do adults need per day?
Adults 19 to 50 need 1,000 mg a day. Women over 50 and everyone over 70 need 1,200 mg a day, according to the NIH.
Which foods are highest in calcium?
Milk, yogurt and cheese are the main sources, along with canned sardines and salmon with bones, kale, broccoli, bok choy and fortified foods and drinks.
Which calcium supplement is best?
Calcium carbonate is absorbed best with food, while calcium citrate can be taken with or without food. Your doctor can advise which suits you.
What is the upper limit for calcium?
For adults 19 to 50 years it is 2,500 mg a day, and for adults 51 and older it is 2,000 mg a day, from all sources.
Does calcium interfere with thyroid medicine?
Yes. Levothyroxine is not absorbed well within 4 hours of a calcium carbonate supplement, so space them apart.
Related reading: Vitamin D daily needs and sources | Zinc daily needs and safe limits | Iron Deficiency guide
Sources
- NIH Office of Dietary Supplements: Calcium fact sheet for consumers
- NIH Office of Dietary Supplements: Vitamin D fact sheet for consumers
Medical disclaimer: this article is for general information and does not replace advice from a qualified doctor. Do not start, stop or change any supplement or medicine without medical advice.