What is calcium?

Calcium (Ca) is a chemical element and is an alkaline earth metal. It is essential for all living organisms and is found in many foods. Calcium is the fifth most abundant element in the Earth’s crust and the most abundant mineral in the human body.

What does calcium do for your body?

There is approximately 2-3% of calcium per weight in an adult.

A total of 99% of the calcium is stored in the bones and teeth, supporting its structure. Bones are the largest storage site of calcium in the body and serve as a source of calcium ready to be released in order to maintain a constant balance of calcium in the blood, intracellular fluids and muscles.

The remaining 1% supports the body’s critical metabolic functions such as widening of the blood vessels, regulation of the hearts’ functioning, vascular contraction, contraction and relaxation of the muscles and hormone regulation. Calcium also plays a role in the enzyme function, blood clotting, signaling between cells, and the transmission of messages in the nervous system. (1)Better Health Channel. Calcium. Available here.

Benefits of calcium

There are proven health benefits associated with calcium intake. However, there is a number of positive effects that are believed to be the outcome of calcium consumption that science still  hasn’t proven.

  • Calcium and osteoporosis (bone and teeth health)
    Following the official recommended daily calcium requirement is essential for good bone health. Insufficient calcium weakens the bones.The circulating levels of calcium in the blood is constantly regulated by the bones. They release enough calcium to the bloodstream in order to maintain its equilibrium, since calcium is an important building material.In the long term, the constant release of calcium from the bones causes them to lose their mass and strength, becoming more prone to fractures.This happens in the case of hypocalcemia – a condition where the calcium levels in blood are lower than recommend due to a low calcium diet, or in situations of renal failure or constant use of diuretics.While in the short term, a diet low in calcium doesn’t display any obvious symptoms, the long term consequences are much more serious, since it leads to osteopenia, osteoporosis and has an impact on rickets coupled with vitamin D deficiency. (2)National Academy of Sciences.2011. Dietary Reference Intakes for Calcium and Vitamin D. Available here.

    Bone loss also occurs as part of the aging process. The most vulnerable are women, especially those who are thin, physically inactive, elderly and postmenopausal (due to the estrogen levels). People with a family history of osteoporosis that smoke or drink excessive amounts of alcohol also belong to the risk group of developing bone problems. (3)Osteoporosis Australia. Are your bones in the Danger Zone? Available here.

    An adequate daily supply of calcium, either from diet or supplements, ensures that the calcium homeostatic is maintained and that bones do not need to release calcium.

    Please note that exercise is a crucial factor for bone strength. Calcium and vitamin D require physical exercise to have an effect on the bones. Relying exclusively on supplement pills may not have the desired outcome.  (4)Weaver CM, Gordon CM, Janz KF, Kalkwarf HJ, Lappe JM, Lewis R, et al. The National Osteoporosis Foundation’s position statement on peak bone mass development and lifestyle factors: a systematic review and implementation recommendations. Osteoporosis International. April 2016, Volume 27, Issue 4, pp 1281–1386. Available here.

    There are some claims, linked to the acid-ash hypothesis, that a diet rich in both protein and calcium can cause bone problems. However, evidence has shown the contrary, that it has positive effects on bone health. (read more..)

  • Calcium and mortality from any causes
    No association was found between calcium intake and mortality from all causes. (5)Chung M, Balk EM, Brendel M, Ip S, Lau J, Lee J. Vitamin D and Calcium: A Systematic Review of Health Outcomes. Agency for Healthcare Research and Quality. U.S. Department of Health and Human Services. Available here.
  • Calcium and colon cancer
    Overall, the evidence, from strong, quality studies, that calcium reduces the risk of colorectal cancer is not concrete. Nevertheless, there are some strong indications (observational and epidemiological studies) that calcium plays some role.Colon cancer has a long period of development, making it difficult to study. The observational, epidemiological and experimental studies of the role of calcium in reduction of colorectal cancer risks are currently inconsistent, but there is strong evidence that calcium in dietary or supplemental form may have some protective properties. More studies such as controlled trials and cohort studies are needed to confirm these findings. (6)Biasco G, Paganelli GM. European trials on dietary supplementation for cancer prevention. Ann N Y Acad Sci. 1999;889:152-6. Available here. (7)Kampman E, Slattery ML, Caan B, Potter JD. Calcium, vitamin D, sunshine exposure, dairy products and colon cancer risk (United States). Cancer Causes Control. 2000 May;11(5):459-66. Available here. (8)Heine-Broring R, Winkels RM, Renkema JMS, Kragt Lea, van Orten-Luiten ACB, Tigchelaar EF, Chan D, et al. Dietary supplement use and colorectal cancer risk: A systematic review and meta-analyses of prospective cohort studies. International Journal of Cancer. Volume 136, Issue 10, pages 2388–2401, 15 May 2015. Available here. (9)National Academy of Sciences.2011. Dietary Reference Intakes for Calcium and Vitamin D. Available here.Studies have so far shown with some degree of certainty that calcium supplementations might help in preventing the development of colorectal non-malignant tumors, called adenomas. Adenoma is a precursor to cancer. (10)Baron JA, Beach M, Mandel JS, van Stolk RU, Haile RW, Sandler RS, et al. Calcium Supplements for the Prevention of Colorectal Adenomas. N Engl J Med. 1999 Jan 14;340(2):101-7. Available here.
  • Calcium and breast cancer
    Calcium intakes of 780-1750mg per day are associated with a decreased risk of cancer in premenopausal women. However, studies on postmenopausal women are inconsistent.No association was found between calcium intake and mammographic density. (11)Chung M, Balk EM, Brendel M, Ip S, Lau J, Lee J. Vitamin D and Calcium: A Systematic Review of Health Outcomes. Agency for Healthcare Research and Quality. U.S. Department of Health and Human Services. Available here.
  • Calcium and obesity
    Clinical trials didn’t find a connection between a high calcium diet and weight loss.Dairy intake, which is high in calcium, has no effect on weight loss. (12)Chen M, Pan A, Malik VS, Hu FB. Effects of dairy intake on body weight and fat: a meta-analysis of randomized controlled trials. Am J Clin Nutr. 2012 Oct;96(4):735-47. Epub 2012 Aug 29. Available here. (13)Chung M, Balk EM, Brendel M, Ip S, Lau J, Lee J. Vitamin D and Calcium: A Systematic Review of Health Outcomes. Agency for Healthcare Research and Quality. U.S. Department of Health and Human Services. Available here.
  • Calcium and blood pressure
    The release of calcium into the bloodstream causes vasodilation (widening of the blood vessels) and, therefore, reduces the blood pressure. Calcium intake is associated with a lower blood pressure in hypotensive adults but not in normotensive.A low calcium intake, of 500mg/day or less, in people over 40 years old with hypertension is related to significantly higher risk of hypertension, in comparison with those whose intake is 1100mg or more per day. Calcium supplementation significantly reduces the systolic blood pressure by 2-4 mm Hg in hypertensive adults compared to adults with no supplementation.
  • Calcium and heart health
    There is a strong association between a low calcium intake (less than 696mg/day) and the increased death risk caused by ischemic heart disease in white women between 55-69 years of age.There is also a connection between a low calcium intake (less 500mg per day) and an increased risk of stroke in women in general, in comparison with those who have higher intakes of calcium. (14)Chung M, Balk EM, Brendel M, Ip S, Lau J, Lee J. Vitamin D and Calcium: A Systematic Review of Health Outcomes. Agency for Healthcare Research and Quality. U.S. Department of Health and Human Services. Available here.
  • Calcium and growth
    Calcium supplementation is not associated with weight or height gain in children or adolescents. There is, however, evidence of height gain in children that consume more milk which is associated with a combination of high calcium and protein contents. (15)Chung M, Balk EM, Brendel M, Ip S, Lau J, Lee J. Vitamin D and Calcium: A Systematic Review of Health Outcomes. Agency for Healthcare Research and Quality. U.S. Department of Health and Human Services. Available here.

Food sources of calcium

It is recommended to get your calcium from foods rather than supplements. Supplementation may lead to excessive calcium intake which may have negative health reactions (see below).

The best calcium-rich foods are dairy products such as milk, yogurt and cheese.

Non-dairy calcium rich foods include:

  • Leafy green vegetables, such as turnip greens, collards, broccoli, bok-choy or spinach;
  • Soy products, such as tofu or soy drinks (calcium fortified), for example, soy yogurt or soy milk;
  • Fish with bones, like sardines and salmon;
  • Nuts, such as brazil nuts and almonds;
  • Seeds, especially sesame, chia, flaxseeds and poppy seeds;
  • Calcium fortified foods (check the labels). Please note that many of the calcium fortified foods can be also rich in sugar such as orange juice or breakfast cereals and overall may not be beneficial.
  • Coconut water, blood orange, orange, lemon and blackcurrants.

Best food sources of Calcium

FoodServing Amount of Calcium (mg)% of RDA
for men
Rating % of RDA
for women
Rating
Cheese2 oz (56g)40440.4Excellent40.4Excellent
Poppy seeds1 oz (28g)40340.3Excellent40.3Excellent
Cheese ricotta, low fat1/2 cup (124g)33733.7Excellent33.7Excellent
Milk, cow's1 cup (244g)27627.6Excellent27.6Excellent
Sesame seeds1 oz (28g)27327.3Excellent27.3Excellent
Cheese ricotta1/2 cup (124g)25725.7Excellent25.7Excellent
Yogurt low fat1/2 cup (120g)219.421.9Excellent21.9Excellent
Turnip greens1 cup (144g)19719.7Good19.7Good
Chia seeds1 oz (28g)17717.7Good17.7Good
Cuttlefish, cooked3 oz (85g)15315.3Good15.3Good
Spinach, cooked1/2 cup (90g)14214.2Good14.2Good
Collards, cooked1/2 cup (95g)13313.3Good13.3Good
Soy Yogurt1/2 cup (100g)13213.2Good13.2Good
Perch, cooked3 oz (85g)116.511.6Good11.6Good
Dandelion greens1 cup (55g)10310.3Good10.3Good
Scallops, cooked3 oz (85g)97.79.8-9.8-
Oats, cooked1/2 cup (117g)93.59.4-9.4-
Octopus, cooked3 oz (85g)90.19-9-
Crab, cooked3 oz (85g)88.48.8-8.8-
Soybeans, cooked1/2 cup (86g)87.58.8-8.8-
Clam, cooked3 oz (85g)78.27.8-7.8-
Trout, cooked3 oz (85g)73.17.3-7.3-
Flaxseed1 oz (28g)71.47.1-7.1-
Almonds1 oz (28g)70.37-7-
Pollock, cooked3 oz (85g)65.56.5-6.5-
Navy beans, cooked1/2 cup (91g)636.3-6.3-
Herring, cooked3 oz (85g)62.96.3-6.3-
Soy milk1 cup (250g)62.56.3-6.3-
Pike, cooked3 oz (85g)62.16.2-6.2-
Amaranth, cooked1/2 cup (123g)585.8-5.8-
Coconut water1 cup (240g)57.65.8-5.8-
Egg large2 large (100g)535.3-5.3-
Lobster, cooked3 oz (85g)51.95.2-5.2-
Halibut, cooked3 oz (85g)515.1-5.1-
Blood orangemedium (121g)48.44.8-4.8-
Orangemedium (121g)48.44.8-4.8-
Kale, cooked1/2 cup (65g)46.84.7-4.7-
Arugula1 cup (28g)44.84.5-4.5-
Brazil nuts1 oz (28g)44.84.5-4.5-
Beet greens1 cup (38g)44.54.5-4.5-
Carp, cooked3 oz (85g)44.24.4-4.4-
Rhubarb1 stalk (51g)43.94.4-4.4-
Crayfish, cooked3 oz (85g)43.44.3-4.3-
Watercress1 cup (34g)40.84.1-4.1-
Chickpeas, cooked1/2 cup (82g)40.24-4-
Pinto beans, cooked1/2 cup (85,5g)39.33.9-3.9-
Lemon1 oz (28g)37.53.8-3.8-
Bok choy1/2 cup (35g)36.83.7-3.7-
Green cabbage, cooked1/2 cup (75g)363.6-3.6-
Haddock, cooked3 oz (85g)35.73.6-3.6-
Snapper, cooked3 oz (85g)343.4-3.4-
Shrimp, cooked3 oz (85g)33.13.3-3.3-
Broccoli florets, cooked1/2 cup (78g)32.23.2-3.2-
Hazelnuts1 oz (28g)31.93.2-3.2-
Red cabbage1/2 cup (75g)31.53.2-3.2-
Abalone, cooked3 oz (85g)31.53.1-3.1-
Tofu1 cup (100g)313.1-3.1-
Blackcurrants1/2 cup (56g)30.83.1-3.1-
Pistachios1 oz (28g)30.83.1-3.1-
Parsnip, cooked1/2 cup (78g)28.92.9-2.9-
Brussels sprouts, cooked1/2 cup (78g)28.12.8-2.8-
Mussel, cooked3 oz (85g)28.12.8-2.8-
Adzuki beans, cooked1/2 cup (100g)282.8-2.8-
Green beans, cooked1/2 cup (62,5g)27.52.8-2.8-
Walnuts1 oz (28g)27.42.7-2.7-
Grapefruitmedium (123g)27.12.7-2.7-
Sweet potato, cooked1/2 cup (100g)272.7-2.7-
Bread, mulitgrain1 slice (26g)26.82.7-2.7-
Kiwifruit skin on1 medium (76g)25.62.6-2.6-
Radish4 medium (100g)252.5-2.5-
Kidney beans, cooked1/2 cup (88,5g)24.82.5-2.5-
Squash, cooked1/2 cup (90g)24.32.4-2.4-
Currants, dried1 oz (28g)24.12.4-2.4-
Macadamia1 oz (28g)23.82.4-2.4-
Rye1 slice (32g)23.42.3-2.3-
Black beans, cooked1/2 cup (86g)23.22.3-2.3-
Figs1 large (64g)22.42.2-2.2-
Eel, cooked3 oz (85g)22.12.2-2.2-
Green peas, cooked1/2 cup (80g)21.62.2-2.2-
Fennel1/2 cup (43,5g)21.32.1-2.1-
Turkey, cooked3 oz (85g)21.32.1-2.1-
Blackberries1/2 cup (72g)20.92.1-2.1-
Asparagus, cooked1/2 cup (90g)20.72.1-2.1-
Carrot1 medium (61g)20.12-2-
Celery1/2 cup (50g)202-2-
Coconut milk1/2 cup (120g)202-2-
Jackfruit1/2 cup (82,5g)19.82-2-
Pecans1 oz (28g)19.62-2-
Lentils, cooked1/2 cup (99g)18.81.9-1.9-
Chocolate 70% cocoa0.5 oz (13,3g)18.71.9-1.9-
Cumin1 tsp (2g)18.61.9-1.9-
Pumpkin, cooked1/2 cup (122,5g)18.41.8-1.8-
Heavy cream1 oz (28g)18.21.8-1.8-
Dates, pitted1 oz (28g)181.8-1.8-
Chard1 cup (36g)17.91.8-1.8-
Grouper, cooked3 oz (85g)17.91.8-1.8-
Veal lean, cooked3 oz (85g)17.81.8-1.8-
Boysenberries1/2 cup (66g)17.81.8-1.8-
Artichokes, cooked1/2 cup (84g)17.61.8-1.8-
Beef, lean3 oz (85g)171.7-1.7-
For Table Legend & Data Sources Information click here.

How much calcium per do I need?

The daily calcium requirement varies depending on a few factors:

  • If on a formula, infants need more calcium since the calcium from the formula is not as well absorbed as from the mother’s milk;
  • Young children have high calcium needs since their skeletal system is still growing;
  • Teenagers need more calcium, since this is a crucial time for building the peak bone mass. Future bone health (including the risk of osteoporosis) depends on how dense the bones get during these years.
  • Pregnancy requires more calcium for the development of the baby;
  • Aging is an inevitable cause of bone loss. A calcium rich diet slows down the age-related bone loss.
  • Women tend to have a greater bone loss than men, especially close to menopause.
  • People with a larger body frame require more calcium than people with a smaller body frame.

Recommendations for Calcium (mg/day)

Life Stage Age RDA for menUL for menRDA for women UL for women
Infants 0-6 months200 (AI) 1,000 200 (AI) 1,000
Infants 6-12 months 260 (AI) 1,500260 (AI) 1,500
Children 1-3 years 700 2,500700 2,500
Children4-8 years 1,000 2,5001,000 2,500
Children 9-13 years 1,300 3,0001,300 3,000
Adolescents 14-18 years 1,300 3,0001,300 3,000
Adults 19-50 years 1,000 2,5001,000 2,500
Adults 51-70 years 1,000 2,0001,200 2,000
Adults > 70 years 1,200 2,0001,200 2,000
Pregnancy 14-18 years-1,300 2,500
Pregnancy 19-50 years-1,000 2,500
Breast-feeding 14-18 years-1,300 2,500
Breast-feeding 19-50 years-1,0002,500
For Table Legend & Data Sources Information click here.

What can too much calcium cause?

Daily intake recommendations for calcium

  • Calcium and gastrointestinal upsets
    Too much calcium may cause bloating and constipation. Calcium supplementation should not exceed the recommended daily allowance. (16)Better Health Channel. Calcium. Available here.
  • Calcium and prostate cancer
    Higher calcium intake and dairy foods or both by men (>1,500 mg or >2,000 mg per day) is slightly associated with an increased risk of developing prostate cancer compared to intakes of 500-1000 mg per day. The studies are inconsistent, however, and more studies are suggested to confirm these findings.  (17)Chung M, Balk EM, Brendel M, Ip S, Lau J, Lee J. Vitamin D and Calcium: A Systematic Review of Health Outcomes. Agency for Healthcare Research and Quality. U.S. Department of Health and Human Services. Available here. (18)Aune D, Rosenblatt D, Chan D, Vieira AR, Vieira R, Greenwood DC, et al. Dairy products, calcium, and prostate cancer risk: a systematic review and meta-analysis of cohort studies. Am J Clin Nutr. ajcn.067157. Available here.
  • Calcium and kidney stones
    The studies on calcium supplementation and association with the risk of kidney stone formation in postmenopausal women are conflicting. More research is needed. (19)Harris SS, Dawson-Hughes B. Effects of Hydration and Calcium Supplementation on Urine Calcium Concentration in Healthy Postmenopausal Women. Journal of the American College of Nutrition. Volume 34, Issue 4, 2015. Available here. (20)Jackson RD, LaCroix AZ, Gass M, Wallace RB, Robbins J, Lewis CE, et al. Calcium plus vitamin D supplementation and the risk of fractures. N Engl J Med. 2006 Feb 16;354(7):669-83. Available here. (21)Haghighi A, Samimagham H, Gahardehi G. Calcium and Vitamin D Supplementation and Risk of Kidney Stone Formation in Postmenopausal Women. Iranian Journal of Kidney Diseases7.3 (May 2013): 210-3. Available here. (22)Kuang W. Oral Calcium Supplementation Does Not Increase Risk of Calcium Nephrolithiasis in Postmenopausal Women. (2015). School of Physician Assistant Studies. Paper 509. Available here.Association was not found in patients with osteoporosis. (23)Candelas G, Martinez-Lopez JA, Rosario MP, Loza CE. Calcium supplementation and kidney stone risk in osteoporosis: a systematic literature review. Experimental rheumatology. 2012. Available here.

References   [ + ]

1. Better Health Channel. Calcium. Available here.
2. National Academy of Sciences.2011. Dietary Reference Intakes for Calcium and Vitamin D. Available here.
3. Osteoporosis Australia. Are your bones in the Danger Zone? Available here.
4. Weaver CM, Gordon CM, Janz KF, Kalkwarf HJ, Lappe JM, Lewis R, et al. The National Osteoporosis Foundation’s position statement on peak bone mass development and lifestyle factors: a systematic review and implementation recommendations. Osteoporosis International. April 2016, Volume 27, Issue 4, pp 1281–1386. Available here.
5. Chung M, Balk EM, Brendel M, Ip S, Lau J, Lee J. Vitamin D and Calcium: A Systematic Review of Health Outcomes. Agency for Healthcare Research and Quality. U.S. Department of Health and Human Services. Available here.
6. Biasco G, Paganelli GM. European trials on dietary supplementation for cancer prevention. Ann N Y Acad Sci. 1999;889:152-6. Available here.
7. Kampman E, Slattery ML, Caan B, Potter JD. Calcium, vitamin D, sunshine exposure, dairy products and colon cancer risk (United States). Cancer Causes Control. 2000 May;11(5):459-66. Available here.
8. Heine-Broring R, Winkels RM, Renkema JMS, Kragt Lea, van Orten-Luiten ACB, Tigchelaar EF, Chan D, et al. Dietary supplement use and colorectal cancer risk: A systematic review and meta-analyses of prospective cohort studies. International Journal of Cancer. Volume 136, Issue 10, pages 2388–2401, 15 May 2015. Available here.
9. National Academy of Sciences.2011. Dietary Reference Intakes for Calcium and Vitamin D. Available here.
10. Baron JA, Beach M, Mandel JS, van Stolk RU, Haile RW, Sandler RS, et al. Calcium Supplements for the Prevention of Colorectal Adenomas. N Engl J Med. 1999 Jan 14;340(2):101-7. Available here.
11. Chung M, Balk EM, Brendel M, Ip S, Lau J, Lee J. Vitamin D and Calcium: A Systematic Review of Health Outcomes. Agency for Healthcare Research and Quality. U.S. Department of Health and Human Services. Available here.
12. Chen M, Pan A, Malik VS, Hu FB. Effects of dairy intake on body weight and fat: a meta-analysis of randomized controlled trials. Am J Clin Nutr. 2012 Oct;96(4):735-47. Epub 2012 Aug 29. Available here.
13. Chung M, Balk EM, Brendel M, Ip S, Lau J, Lee J. Vitamin D and Calcium: A Systematic Review of Health Outcomes. Agency for Healthcare Research and Quality. U.S. Department of Health and Human Services. Available here.
14. Chung M, Balk EM, Brendel M, Ip S, Lau J, Lee J. Vitamin D and Calcium: A Systematic Review of Health Outcomes. Agency for Healthcare Research and Quality. U.S. Department of Health and Human Services. Available here.
15. Chung M, Balk EM, Brendel M, Ip S, Lau J, Lee J. Vitamin D and Calcium: A Systematic Review of Health Outcomes. Agency for Healthcare Research and Quality. U.S. Department of Health and Human Services. Available here.
16. Better Health Channel. Calcium. Available here.
17. Chung M, Balk EM, Brendel M, Ip S, Lau J, Lee J. Vitamin D and Calcium: A Systematic Review of Health Outcomes. Agency for Healthcare Research and Quality. U.S. Department of Health and Human Services. Available here.
18. Aune D, Rosenblatt D, Chan D, Vieira AR, Vieira R, Greenwood DC, et al. Dairy products, calcium, and prostate cancer risk: a systematic review and meta-analysis of cohort studies. Am J Clin Nutr. ajcn.067157. Available here.
19. Harris SS, Dawson-Hughes B. Effects of Hydration and Calcium Supplementation on Urine Calcium Concentration in Healthy Postmenopausal Women. Journal of the American College of Nutrition. Volume 34, Issue 4, 2015. Available here.
20. Jackson RD, LaCroix AZ, Gass M, Wallace RB, Robbins J, Lewis CE, et al. Calcium plus vitamin D supplementation and the risk of fractures. N Engl J Med. 2006 Feb 16;354(7):669-83. Available here.
21. Haghighi A, Samimagham H, Gahardehi G. Calcium and Vitamin D Supplementation and Risk of Kidney Stone Formation in Postmenopausal Women. Iranian Journal of Kidney Diseases7.3 (May 2013): 210-3. Available here.
22. Kuang W. Oral Calcium Supplementation Does Not Increase Risk of Calcium Nephrolithiasis in Postmenopausal Women. (2015). School of Physician Assistant Studies. Paper 509. Available here.
23. Candelas G, Martinez-Lopez JA, Rosario MP, Loza CE. Calcium supplementation and kidney stone risk in osteoporosis: a systematic literature review. Experimental rheumatology. 2012. Available here.

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