Medically reviewed by Sara Osman,RD,PT
Introduction
Calcium is the most abundant mineral in our bodies and it makes up 1.9% of the body by weight. [1,2]
The body gets calcium in two ways, either by eating calcium-rich foods or supplements or by drawing calcium from the body or bones specifically. [4]
The borrowed calcium from bones is usually replaced at a later stages when the nutrient levels go up, but it might not happen always. [4]
Calcium salts provides rigidity to the skeleton whereas calcium ions help in the metabolic process. [2]
Different hormones work with the kidney to control the calcium reserves in the body as well as excretion. [4]
In case of calcium deficiency, the body will remove calcium from the bones. [4]
- Ingested calcium is mixed with digestive juice calcium to be absorbed in the proximal small intestine. [2]
Net absorption percentage increases with intakes and peaks at 35% at an intake of 400 mg and then falls off as intake increases further. [2] - Net calcium absorption declines with ageing. It could be as high as 60% in infants and young children but decrease to 15-20% in adulthood and so forth. [1]
- However, certain anti-nutrients like oxalates and phytates can bind to calcium and decrease its bioavailability. [3,4]
- Almost 99% of the calcium is stored in the bones and teeth. [1,3]
- The remaining 1% is used by the body for nerve transmission, muscular function, intracellular signalling and other such important functions. [1]
- Bone mineral serves as the ultimate reservoir for the calcium circulating in the extracellular fluid.[2]
- When calcium levels drop in the blood, certain hormones signal the bone to release more calcium in the bloodstream, activate vitamin D to improve absorption of calcium in the intestines and reduce calcium excretion in urine. [4]
- Some of the absorbed calcium is excreted from the body in urine, faeces and sweat. [1]
- The average calcium losses in excretion are estimated to be around 240 mg/day. [7]
Body Functions
Recommended Daily Intake
Advertisement
Deficiency Symptoms
Calcium Food Sources
Advertisement
Excessive Intake/ Toxicity Side Effects
Groups At Risk of Calcium Deficiency
Calcium Interaction With Other Nutrients
- Vitamin D – Vitamin D intake improves calcium absorption. [1]
- Iron and Zinc – High calcium intake can possibly interfere with the absorption of iron and zinc. High calcium phosphate intake (1,360 mg/day) may decrease zinc absorption. [1,3]
- Sodium – High sodium intake increases urinary calcium excretion as it is believed that sodium competes with calcium for reabsorption in renal tubules. [1,2]
- Protein – High protein intake, especially animal protein and certain grains (acid ash protein) may increase urinary calcium excretion
and is therefore thought to negatively affect calcium status. [1,2,3,6]
One study found that 0.85 mg of calcium was lost for each gram of protein in the diet. [2] - Magnesium – Magnesium deficiency may be a result of high calcium intake. [3] Calcium intakes in excess of 2600 mg/day have shown to decrease magnesium absorption.[3]
- Oxalic and Phytic acid – Foods rich in oxalic or phytic acid may inhibit calcium absorption. [3]
Nutrient Profiles For Food Groups
Medically reviewed by Sara Osman,RD,PT
About Veganism
Learn more about the origins , different types and potential nutritional deficienciesOur Mission
Learn more about our mission, our approach and the story behind the project2050 Challenges
Learn more about the Environmental, Health and Societal challenges of the futureAdvertisement
Subscribe to Newsletter
