Calcium
What it is and what it does
- Calcium is the most abundant mineral in the body. (NIH Office of Dietary Supplements. Calcium Fact Sheet for Consumers (updated 2023-09-14))
- Almost all of the body's calcium is in bones and teeth, giving them structure and hardness. (NIH Office of Dietary Supplements. Calcium Fact Sheet for Consumers (updated 2023-09-14))
- Calcium is needed for muscles to move and for nerves to carry messages between the brain and the body. (NIH Office of Dietary Supplements. Calcium Fact Sheet for Consumers (updated 2023-09-14))
- Calcium helps blood vessels move blood and helps release hormones. (NIH Office of Dietary Supplements. Calcium Fact Sheet for Consumers (updated 2023-09-14))
- A small pool of calcium in blood and tissues controls blood-vessel contraction, muscle function, blood clotting, nerve signals and hormone release. (NIH Office of Dietary Supplements. Calcium Fact Sheet for Health Professionals (updated 2026-06-22))
- Bone is continuously remodelled: calcium is constantly removed and laid down in new bone. (NIH Office of Dietary Supplements. Calcium Fact Sheet for Health Professionals (updated 2026-06-22))
Why it matters
- Calcium deficiency can reduce bone strength and lead to osteoporosis (fragile bones). (NIH Office of Dietary Supplements. Calcium Fact Sheet for Health Professionals (updated 2026-06-22))
- Calcium deficiency can also cause rickets in children and bone disorders in adults, though these are more often caused by vitamin D deficiency. (NIH Office of Dietary Supplements. Calcium Fact Sheet for Health Professionals (updated 2026-06-22))
- Growing children and adolescents need more calcium. (ICMR-NIN. Dietary Guidelines for Indians 2024)
- Too much: very high blood calcium is usually caused by a health condition (such as high parathyroid hormone or cancer), not by high calcium intake. (NIH Office of Dietary Supplements. Calcium Fact Sheet for Consumers (updated 2023-09-14))
General information, not medical advice — for your own needs, ask a doctor or dietitian.
How much is needed
| Who | Amount | What the figure is | Whose figure |
|---|---|---|---|
| Adult man, sedentary work | 1000 mg/day | recommended dietary allowance | ICMR-NIN 2020 |
| Adult woman, sedentary work | 1000 mg/day | recommended dietary allowance | ICMR-NIN 2020 |
| Pregnant woman | 1000 mg/day | recommended dietary allowance | ICMR-NIN 2020 |
| Adult men and women (and pregnancy where stated) | 2500 mg/day | safe upper limit | ICMR-NIN 2020 |
| Adult man and adult woman (text) | 1000 mg/day | recommended dietary allowance | ICMR-NIN 2020 |
Sources: ICMR-NIN Nutrient Requirements for Indians 2020, as given by FSSAI (Direction of 2 Aug 2021); ICMR-NIN Nutrient Requirements for Indians 2020 (Short Report)
In every millet and pseudo-cereal, per 100 g raw
| Grain | Amount | Source |
|---|---|---|
| Ragi (finger millet) | 364 mg | IFCT A010 |
| Quinoa | 198 mg | IFCT A009 |
| Teff | 180 mg | USDA FDC 169747 |
| Rajgira (amaranth) | 162 mg | IFCT A002 |
| Fonio | 40 mg | FAO WAFCT 2019 |
| Foxtail millet | 31 mg | NIN 2007 via ICAR-IIMR |
| Jowar (sorghum) | 27.6 mg | IFCT A005 |
| Bajra (pearl millet) | 27.35 mg | IFCT A003 |
| Barnyard millet | 20 mg | NIN 2007 via ICAR-IIMR |
| Kuttu (buckwheat) | 18 mg | USDA FDC 170286 |
| Little millet | 16.06 mg | IFCT A016 |
| Kodo millet | 15.27 mg | IFCT A017 |
| Proso millet | 8 mg | USDA FDC 169702 |
Each grain has ONE source, named on its page: IFCT = Indian Food Composition Tables 2017 (ICMR-NIN) with its food code; USDA FDC; FAO WAFCT 2019; NIN 2007 via ICAR-IIMR. Values exactly as printed, not converted — tables differ in method, so compare within a source. Published values for the grain, not a laboratory test of our packs.
Absorption and food
- Vitamin D is required for active calcium absorption in the gut and for keeping blood calcium normal. (NIH Office of Dietary Supplements. Calcium Fact Sheet for Health Professionals (updated 2026-06-22))
- Sunlight exposure keeps vitamin D status up, which helps calcium absorption (ICMR-NIN suggests about 30 minutes, preferably 11 am-2 pm). (ICMR-NIN. Dietary Guidelines for Indians 2024)
- Oxalic acid and phytic acid in some plants bind calcium and lower its absorption. (NIH Office of Dietary Supplements. Calcium Fact Sheet for Health Professionals (updated 2026-06-22))
- Example: about 5% of calcium is absorbed from spinach versus 27% from milk. (NIH Office of Dietary Supplements. Calcium Fact Sheet for Health Professionals (updated 2026-06-22))
- In a varied diet, these oxalate and phytate effects probably matter little. (NIH Office of Dietary Supplements. Calcium Fact Sheet for Health Professionals (updated 2026-06-22))
- The share absorbed falls as intake rises: about 45% at 200 mg/day but only 15% above 2,000 mg/day. (NIH Office of Dietary Supplements. Calcium Fact Sheet for Health Professionals (updated 2026-06-22))
- Higher sodium (salt) intake increases calcium loss in urine. (ICMR-NIN. Dietary Guidelines for Indians 2024)
- Phytic acid in cereals and pulses hinders mineral absorption; boiling or pressure-cooking lowers it considerably, making iron, calcium, magnesium and zinc more absorbable. (ICMR-NIN. Dietary Guidelines for Indians 2024)
- Milk, curd, sesame seeds, ragi and green leafy vegetables such as amaranth are good sources of calcium. (ICMR-NIN. Dietary Guidelines for Indians 2024)
- Milk is the best source of well-absorbed calcium (but a poor source of iron). (ICMR-NIN. Dietary Guidelines for Indians 2024)