Too much versus too little CALCIUM (Ca)

The body of an adult contains more than 1 kg of calcium: 98 % in the form of calcium phosphate crystals in the bones and 2 % in the blood (with an important role in blood clotting).

In the bones, calcium is not permanently fixed but is continuously renewed, being absorbed from food and fixed in the bone tissue or excreted through urine, faeces or sweat. Since bone mass is built up in childhood and adolescence, an additional intake of calcium is necessary between the ages of 10 and 19.

The body's absorption of calcium is influenced by several factors:

• the ratio between Ca and P (phosphorus) – 2/1 in the bones;
• the presence of proteins or amino acids;
• the presence of lactose, lactic acid, citric acid, lipase and bile salts;
• the presence of vitamins: D (particularly D2 and D3);
• the content of vitamins A and C;
• stomach acid;
• the quality of the food;
• sex (in men the absorption of calcium is higher than in women);
• Excess salt and acidic drinks increase the rate at which calcium is excreted from the body.

Physical exercise is a very important way of fixing calcium in the bones.

Considerable amounts of calcium can be lost through sweat, but most of it is excreted through the large intestine and the urine.

The role of calcium:

• enters into the structure of the skeletal system and the teeth;
• takes part in blood clotting, iron metabolism and the acid-base balance;
• takes part in the mechanism of muscle contraction and is responsible for the health of the cardiovascular system;
• together with magnesium it reduces neuromuscular excitability (it is used in neuropsychiatry to treat insomnia);
• allows cells to divide and multiply;
• mediates the action of hormones.

Hypocalcaemia, a lack of Ca in the body, leads to tooth decay and rickets in children or to osteoporosis in adults and older people. Osteoporosis is also caused by excess acid in food, which removes calcium from the bones and directs it to other areas. Drinking beverages with a high phosphorus content leads to a rapid loss of calcium. Hypocalcaemia can show itself through insomnia, irritability, palpitations, depressive states, bloating, paraesthesia, headaches, dizziness, difficulty concentrating and shortness of breath. During the menopause, women lose between 2 and 5 % of their bone calcium a year, and with hormonal imbalances the losses can be between 3 and 8 %.

An excess of calcium in the body is rarer and is usually due to calcium supplements with vitamin D or to eating foods enriched with calcium. A rise in calcium can lead to stones being deposited in the kidneys, in the bladder or in the aorta. Hypercalcaemia can show itself through nausea, vomiting, asthenia, myo-osteoarticular pain, drowsiness, constipation and high blood pressure.

The richest sources of calcium are dairy products, drinking water, wine, fish and eggs, and smaller amounts of calcium are found in vegetables, fruit, cereals and meat.