Keywords: teeth and bone health, muscle contractions
- Acetylcholine synthesis
- Action of many hormones
- Action of saliva and many enzymes
- Blood clotting
- Blood pressure regulation
- Conversion of glycogen to glucose
- Muscle contractions
- Nerve impulses (release of neurotransmitters)
- Structure of cells
- Structure of bones and teeth
- Vitamin B12 absorption
Good food sources
- Cheese (especially hard cheeses)
- Canned fish (if bones are consumed)
- Cow’s milk
- Leafy green vegetables
- Pulses (legumes)
- Root vegetables
- Convulsions and seizures
- Some cases of gum disease
- Loss of muscle tone
- Muscle cramps
- Osteoporosis (brittle bone disease)
- Rickets or osteomalacia (bone softening)
The bioavailability of calcium is reduced by deficiencies of vitamin D and stomach acid, by high levels of dietary fibre, phytic acid (found in raw whole grains), oxalic acid (found in spinach) or saturated fat, and by a high protein or phosphorus intake, which causes increased losses of calcium in the urine. Sodium and caffeine also cause increased urinary losses of calcium.
60 per cent of calcium is lost when flour is refined. Although by law many countries require white flour to be fortified with calcium to compensate for this, the form of calcium which is used (chalk) is considered to have low bioavailability.
A 1985 research study points out that the conditions which produce calcium deficiency may also lead to a shift of calcium from bone to soft tissue. This may promote not only osteoporosis but also arteriosclerosis and high blood pressure, due to increased levels of calcium in the blood vessel walls. Motor neurone disease and senile dementia could result from the calcium being deposited in the central nervous system. Another effect of calcium deficiency may be a shift of calcium from outside the cells (normal) to inside the cells (abnormal), which would encourage the development of diabetes and immune deficiency. (Fujita T: Aging and calcium as an environmental factor. J Nutr Sci Vitaminol 31(Suppl):S15-19, 1985.)
Many people believe that the regular consumption of dairy produce (milk, cheese, yoghurt etc.) is essential to prevent calcium deficiency. This is in fact only true for individuals who eat a diet which would otherwise be very poor in calcium. The consumption of a good whole-food diet rich in vegetables and nuts ensures not only a high calcium but also a high magnesium intake. On the other hand dairy products are a poor source of magnesium, and individuals who rely on dairy produce for their nutrient intake can end up with a relative magnesium insufficiency. Calcium deficiency sometimes does not respond to supplementation unless any concurrent magnesium deficiency is also treated.
High dietary levels of calcium and potassium can help to prevent some of the harmful effects of excess sodium consumption.
Information compiled by Linda Lazarides
Naturopathic Nutritionist, Author, Educator