Dietary Allowance

Intake recommendations for calcium and other nutrients are provided in the Dietary Reference Intakes (DRIs) developed by the Food and Nutrition Board (FNB) at the Institute of Medicine of the National Academies (formerly National Academy of Sciences).1 DRI is the general term for a set of reference values used for planning and assessing the nutrient intakes of healthy people. These values, which vary by age and gender2 include:

  • Recommended Dietary Allowance (RDA): average daily level of intake sufficient to meet the nutrient requirements of nearly all (97%-98%) healthy individuals.
  • Adequate Intake (AI): established when evidence is insufficient to develop an RDA and is set at a level assumed to ensure nutritional adequacy.
  • Tolerable Upper Intake Level (UL): maximum daily intake unlikely to cause adverse health effects.3

The FNB established AIs for the amounts of calcium required to maintain adequate rates of calcium retention and bone health in healthy people. They are listed in Table 1 in milligrams (mg) per day.

Table 1: Adequate Intakes (AIs) for Calcium4

Age Male Female Pregnant Lactating
Birth to 6 months 210 mg 210 mg    
7-12 months 270 mg 270 mg    
1-3 years 500 mg 500 mg    
4-8 years 800 mg 800 mg    
9-13 years 1,300 mg 1,300 mg    
14-18 years 1,300 mg 1,300 mg 1,300 mg 1,300 mg
19-50 years 1,000 mg 1,000 mg 1,000 mg 1,000 mg
50+ years 1,200 mg 1,200 mg    

mg=milligrams

Intakes & Status

Many Americans do not ingest recommended amounts of calcium from food.

Approximately 44% of boys and 58% of girls aged 6–11 fell short in 1994–1996, as did 64% of boys and 87% of girls aged 12–19 years and 55% of men and 78% of women aged 20 years or older, according to the nationwide Continuing Survey of Food Intakes of Individuals.5 The National Health and Nutrition Examination Survey 1999-2000 found that average calcium intakes were 1,081 and 793 mg/day for boys and girls ages 12-19 years, respectively; 1,025 and 797 mg/day for men and women 20-39 years; and 797 and 660 mg/day for men and women ≥60 years. Overall, females are less likely than males to get recommended intakes of calcium from food.6

Not all calcium consumed is actually absorbed in the gut. Among the factors that affect its absorption are the following:

  • Amount consumed: the efficiency of absorption decreases as the amount of calcium consumed at a meal increases.7
  • Age: net calcium absorption is as high as 60% in infants and young children, who need substantial amounts of the mineral to build bone.8 Absorption decreases to 15%-20% in adulthood and continues to decrease as people age; this explains the higher recommended calcium intakes for ages ≥51 years.9 10 11
  • Vitamin D intake: this nutrient, obtained from food and produced by skin when exposed to sunlight of sufficient intensity, improves calcium absorption.12
  • Other components in food: phytic acid and oxalic acid, found naturally in some plants, bind to calcium and can inhibit its absorption. Foods with high levels of oxalic acid include spinach, collard greens, sweet potatoes, rhubarb, and beans. Among the foods high in phytic acid are fiber-containing whole-grain products and wheat bran, beans, seeds, nuts, and soy isolates.13 The extent to which these compounds affect calcium absorption varies. Research shows, for example, that eating spinach and milk at the same time reduces absorption of the calcium in milk.14 In contrast, wheat products (with the exception of wheat bran) do not appear to have a negative impact on calcium absorption.15 For people who eat a variety of foods, these interactions probably have little or no nutritional consequence and, furthermore, are accounted for in the overall calcium DRIs, which take absorption into account.

Some absorbed calcium is eliminated from the body in urine, feces, and sweat. This amount is affected by such factors as the following:

  • Sodium, potassium, and protein intakes: high intakes of sodium and protein increase calcium excretion.16 17 Adding more potassium to a high-sodium diet might help decrease calcium excretion, particularly in postmenopausal women.18 19
  • Caffeine intake: this stimulant in coffee and tea can modestly increase calcium excretion and reduce absorption.20 One cup of regular brewed coffee, for example, causes a loss of only 2-3 mg of calcium.21 Moderate caffeine consumption (1 cup of coffee or 2 cups of tea per day) in young women has no negative effects on bone.22
  • Alcohol intake: alcohol intake can affect calcium status by reducing its absorption23 and by inhibiting enzymes in the liver that help convert vitamin D to its active form.24 However, the amount of alcohol required to affect calcium status and whether moderate alcohol consumption is helpful or harmful to bone is unknown.
  • Phosphorus intake: the effect of this mineral on calcium excretion is minimal. Several observational studies suggest that consumption of carbonated soft drinks with high levels of phosphate is associated with reduced bone mass and increased fracture risk. However, the effect is probably due to replacing milk with soda rather than the phosphorus itself.25 26
  • Fruit and vegetable intakes: these foods, when metabolized, shift the acid/base balance of the body towards the alkaline by producing bicarbonate, which reduces calcium loss. Metabolic acids produced by diets high in protein and cereal grains, for example, cause bone to release minerals such as calcium and phosphates and alkaline salts that neutralize the excess acid. In one experiment, women ≥50 years of age who took supplements of bicarbonate showed significant reductions in calcium excretion, indicating reduced bone resorption.27

Related Links:  What is Calcium? | What are some important links between calcium and my health? | What foods provide calcium? | How much calcium do I need? | What happens if I do not get enough calcium? | Do I need extra calcium? | Can calcium be harmful? | Does calcium interact with any medicines or supplements?

Disclaimer

Reasonable care has been taken in preparing this document and the information provided herein is believed to be accurate. However, this information is not intended to constitute an "authoritative statement" under Food and Drug Administration rules and regulations.

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The mission of the Office of Dietary Supplements (ODS) is to strengthen knowledge and understanding of dietary supplements by evaluating scientific information, stimulating and supporting research, disseminating research results, and educating the public to foster an enhanced quality of life and health for the U.S. population.

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Health professionals and consumers need credible information to make thoughtful decisions about eating a healthful diet and using vitamin and mineral supplements. These Fact Sheets provide responsible information about the role of vitamins and minerals in health and disease. Each Fact Sheet in this series received extensive review by recognized experts from the academic and research communities.

The information is not intended to be a substitute for professional medical advice. It is important to seek the advice of a physician about any medical condition or symptom. It is also important to seek the advice of a physician, registered dietitian, pharmacist, or other qualified health professional about the appropriateness of taking dietary supplements and their potential interactions with medications.

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Footnotes

  1. Standing Committee on the Scientific Evaluation of Dietary Reference Intakes, Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D and Fluoride. Washington, DC: National Academy Press, 1997. [↩]
  2. Standing Committee on the Scientific Evaluation of Dietary Reference Intakes, Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D and Fluoride. Washington, DC: National Academy Press, 1997. [↩]
  3. Standing Committee on the Scientific Evaluation of Dietary Reference Intakes, Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D and Fluoride. Washington, DC: National Academy Press, 1997. [↩]
  4. Standing Committee on the Scientific Evaluation of Dietary Reference Intakes, Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D and Fluoride. Washington, DC: National Academy Press, 1997. [↩]
  5. U.S. Department of Agriculture. Results from the United States Department of Agriculture's 1994-96 Continuing Survey of Food Intakes by Individuals/Diet and Health Knowledge Survey, 1994-96. [↩]
  6. Ervin RB, Wang C-Y, Wright JD, Kennedy-Stephenson J. Dietary intake of selected minerals for the United States population: 1999-2000. Advance Data from Vital and Health Statistics, number 341. Hyattsville, MD: National Center for Health Statistics, 2004. [↩]
  7. Standing Committee on the Scientific Evaluation of Dietary Reference Intakes, Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D and Fluoride. Washington, DC: National Academy Press, 1997. [↩]
  8. Standing Committee on the Scientific Evaluation of Dietary Reference Intakes, Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D and Fluoride. Washington, DC: National Academy Press, 1997. [↩]
  9. Standing Committee on the Scientific Evaluation of Dietary Reference Intakes, Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D and Fluoride. Washington, DC: National Academy Press, 1997. [↩]
  10. National Institutes of Health. Optimal calcium intake. NIH Consensus Statement: 1994;12:1-31. [PubMed abstract] [↩]
  11. Heaney RP, Recker RR, Stegman MR, Moy AJ. Calcium absorption in women: relationships to calcium intake, estrogen status, and age. J Bone Miner Res 1989;4:469-75. PubMed abstract [↩]
  12. Standing Committee on the Scientific Evaluation of Dietary Reference Intakes, Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D and Fluoride. Washington, DC: National Academy Press, 1997. [↩]
  13. Standing Committee on the Scientific Evaluation of Dietary Reference Intakes, Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D and Fluoride. Washington, DC: National Academy Press, 1997. [↩]
  14. Weaver CM, Heaney RP. Isotopic exchange of ingested calcium between labeled sources: evidence that ingested calcium does not form a common absorptive pool. Calcif Tissue Int 1991;49:244-7. PubMed abstract [↩]
  15. Weaver CM, Heaney RP, Martin BR, Fitzsimmons ML. Human calcium absorption from whole-wheat products. J Nutr 1991;121:1769-75. PubMed abstract [↩]
  16. Weaver CM, Proulx WR, Heaney RP. Choices for achieving adequate dietary calcium with a vegetarian diet. Am J Clin Nutr 1999;70:543S-8S. PubMed abstract [↩]
  17. Heaney RP. Bone mass, nutrition, and other lifestyle factors. Nutr Rev 1996;54:S3-S10. PubMed abstract [↩]
  18. Sellmeyer DE, Schloetter M, Sebastian A. Potassium citrate prevents increased urine calcium excretion and bone resorption induced by a high sodium chloride diet. J Clin Endocrinol Metab 2002;87:2008-12. PubMed abstract [↩]
  19. Standing Committee on the Scientific Evaluation of Dietary Reference Intakes, Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Water, Potassium, Sodium, Chloride, and Sulfate. Washington, DC: National Academies Press, 2004. [↩]
  20. Barrett-Connor E, Chang JC, Edelstein SL. Coffee-associated osteoporosis offset by daily milk consumption. JAMA 1994;271:280-3. PubMed abstract [↩]
  21. Heaney RP. Bone mass, nutrition, and other lifestyle factors. Nutr Rev 1996;54:S3-S10. PubMed abstract [↩]
  22. Massey LK, Whiting SJ. Caffeine, urinary calcium, calcium metabolism, and bone. J Nutr 1993;123:1611-4. PubMed abstract [↩]
  23. Hirsch PE, Peng TC. Effects of alcohol on calcium homeostasis and bone. In: Anderson J, Garner S, eds. Calcium and Phosphorus in Health and Disease. Boca Raton, FL: CRC Press, 1996:289-300. [↩]
  24. U.S. Department of Agriculture. Results from the United States Department of Agriculture's 1994-96 Continuing Survey of Food Intakes by Individuals/Diet and Health Knowledge Survey, 1994-96. [↩]
  25. Calvo MS. Dietary phosphorus, calcium metabolism and bone. J Nutr 1993;123:1627-33. PubMed abstract [↩]
  26. Heaney RP, Rafferty K. Carbonated beverages and urinary calcium excretion. Am J Clin Nutr 2001;74:343-7. PubMed abstract [↩]
  27. Dawson-Hughes B, Harris SS, Palermo NJ, Castaneda-Sceppa C, Rasmussen HM, Dallal GE. Treatment with potassium bicarbonate lowers calcium excretion and bone resorption in older men and women. J Clin End & Metab 2009;94:96-102. PubMed abstract [↩]

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