Patricia Thompson - NUTRITION TALK FROM TIME to time, one or other of the nutrients attracts more attention. Most recently, there has been a number of advertisements promoting increased intake of calcium for various health benefits. In some cases, extremely high levels are recommended for weight control, sleep disturbances, depression, arthritis and menopausal symptoms.
Of the minerals, calcium is found in the highest concentration in the body. Along with phosphorus and magnesium, it forms the foundation of bone structure, the skeleton and teeth. It is therefore very critical to bone health and growth. Although the bone receives and loses calcium throughout life, the greatest gains in bone density occur during high periods of growth such as adolescence, while the rate of bone loss increases as we get older.
BONE HEALTH
The disease, osteoporosis is believed to be related to calcium deficiency. Although this bone disease appears in mature to old persons, the roots of its cause could actually be due to inadequate calcium intake during our youth. Also, during pregnancy, the developing baby draws calcium from the mother and if her dietary intake is inadequate, she will release calcium from her bone to supply the growing skeleton of her baby. After repeated pregnancies, her bone becomes depleted of calcium and weakens.
Calcium alone is not enough. Calcium works best in relation with other minerals and vitamin D and its metabolism is controlled by hormones. Women suffering with early signs of osteoporosis may need hormone therapy along with calcium supplements to ensure optimal use by the bone. Calcium has also been reported to bring relief for joint pain and arthritis.
HEART, MUSCLE AND NERVE HEALTH
Calcium is central to a variety of other functions such as nerve and muscle activity and blood coagulation. Some types of muscle cramps, especially during pregnancy, are attributed to low levels of calcium, and this can also cause tetany (spasms and twitching of the muscles).
High levels of calcium and magnesium are of benefit to heart health. Persons who drink 'hard' water, containing these minerals, have been found to have fewer heart attacks than persons who drink 'soft' water. Because of its relation to nerve activity, it has been used in depression, anxiety, panic attacks, nervous ticks and twitches, insomnia and hyperactivity.
There is also evidence of benefits against colon and rectal cancer when calcium is taken in high amounts but more research is needed to verify these associations.
GETTING ENOUGH CALCIUM
Calcium is found in foods from both animal and plant sources. High calcium foods include dairy products such as milk, cheese and yogurt; canned, bony fish such as sardines and mackerel, dark green, leafy vegetables such as callaloo, dried peas and beans and fortified soy milk.
The rate of absorption from food averages about 50 per cent but this will vary in the presence of enhancers or inhibitors. Physical activity will increase absorption and bone density so that even intakes, lower than the recommended dose, may be adequate. However, diets high in protein and fat will lower availability so that higher intakes of calcium from the diet would be required.
CALCIUM SUPPLEMENTS
If you prefer artificial sources, make sure the calcium is in an absorbable form, combined with an acid such as hydrochloride, lactate, gluconate, sulphate or orotate. Dolomite and bone meal are relatively unabsorbable and may be contaminated with toxic metals such as lead, arsenic, mercury and aluminium.
As with all supplements, excess can have side effects. Too much calcium can lead to kidney stones, kidney failure, poor muscle tone, constipation, abdominal pains, loss of appetite, nausea and vomiting.
Patricia Thompson M.Sc., Registered Nutritionist, The Nutrition Centre, Eden Gardens.
