Calcium is the most abundant mineral in the human body. Find out what calcium is used for in the body, as well as the needs of different population groups and the foods containing calcium.
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Updated on 07/01/2020
Presentation, food sources and nutritional needs
Definition, functions and roles
Calcium is the most abundant mineral in the human body, amounting to about 1 to 1.2 kg in adults. Ninety-nine per cent of this calcium contributes to the formation and strength of bones and teeth. Non-osseous calcium, despite its small percentage (1%), is involved in multiple essential bodily functions: blood clotting, muscle contraction, nerve conduction, hormone release, etc.
The concentration of calcium in the blood is kept within very narrow limits at the expense of bone reserves. Therefore, the impact of a diet that does not provide enough calcium (a deficient diet), only becomes apparent when changes occur in the bones (poor bone maintenance in young people, decalcification in adults and the elderly).
At all ages, therefore, it is essential to ensure continuous and adequate coverage of calcium needs. This is helped by intakes close to the population reference intakes. This is especially true during childhood and adolescence, when peak bone mass is being established, as well as at the time when physiological ageing of the bones occurs.
In fact, bone is a living tissue that forms and degrades throughout our lives. This means that old bone can be replaced by young bone and the various types of damage sustained by the bone can be repaired.
During the first 20 years of life, formation occurs faster than degradation, which allows bone mass to be acquired and consolidated. Then, from the age of about 30, physiological bone loss occurs (with formation being insufficient to compensate for degradation), followed by amplification of this loss from the age of 50 for women and 60 for men, which provides fertile ground for the development of osteoporosis.
Composition of foods containing calcium
In general, dairy products are major sources of calcium, for the French population. However, calcium levels in different cheeses can vary widely. In addition to dairy products, some leafy vegetables and cabbages, dried fruit and a few mineral waters are also significant sources of calcium.
Population reference intakes
The population reference intakes (PRI) for adults were updated in 2016. They are 1000 mg for young people aged 19-23 years and 950 mg for those over 24 years of age.
Regarding children, the previous reference intakes (French ANCs) in calcium were 500 mg for infants, 700 mg for children aged 4 to 6 years, 900 mg for children aged 7 to 9 years and 1200 mg for those aged up to 19 years. They are in the process of being re-assessed.
Risks of deficiency and excess intake
Signs of calcium deficiency only become apparent when changes in the bones occur in the medium and long term: disorders related to mineralisation defects in osteoid tissue (rickets in children and osteomalacia in adults) or excessive bone loss (osteoporosis in the elderly).
Osteomalacia is a disease affecting adults related to a lack of accumulation of mineral elements in the skeleton. When it occurs in young, growing people, it is called rickets. These diseases lead to bone and muscle pain as well as bone deformation.
Osteoporosis results from a pathological accentuation of bone ageing and is characterised by a very low bone mass and deterioration of bone structure. Its best-known manifestations are vertebral collapse, and wrist and hip (femoral neck) fractures. This disease is three times more common in women than in men. In fact, between the ages of 30 and 80 years, women lose an average of 45% of their initial bone mass, whereas this loss is only 15-20% in men.
In the long term, excessive intake of calcium can, in susceptible individuals, lead to hypercalciuria, and thus urolithiasis and nephrocalcinosis, the risk of which may be increased in cases of hypervitaminosis D. In 2003, the SCF established an upper intake limit of 2500 mg/day.