MOTHER Nature knows best. A nutrient does not just serve one function but has many roles in the body, for instance, calcium. Apart from the fact that it is predominantly in the bones and teeth, calcium is required for the efficient working of the heart, nerves and muscles.
According to the National Institute of Health in America, in the land of cheese and milk, many Americans consume less than the recommended amount of calcium to maintain healthy bones. In Malaysia, many are lactose-intolerant and have to depend on non-dairy sources of calcium.
Symptoms of calcium deficiency are not immediately seen as the body breaks down calcium from bone to meet the shortfall in the blood. This increasingly over time increases the risk of bone loss. Cramping in the feet, dry skin, soft and brittle nails or misshapen nails, hair loss, numbness or tingling, deformed bone development and poor sleeping patterns are some of the symptoms of calcium deficiency.
Elevated blood pressure (hypertension) has also been linked with low levels of calcium though not all animal studies and human trials have been conclusive on this. A study carried out on oral supplementation of 1000mg per day of calcium in 57 borderline and mild-to-moderate high blood pressure for 14 weeks followed by a further 14 weeks without supplementation showed that pre-treatment with calcium lowers blood pressure.
The researchers from the Tianjin Hospital in China suggested increased calcium intake lowers blood pressure in hypertension and that the mechanism is probably due to calcium effect on how the body deals with sodium. Excessive consumption of sodium (from salt) is a common cause of high blood pressure especially in "salt-sensitive" individuals.
A German study published in the journal of Clinical Endocrinology and Metabolism has also shown that calcium together with vitamin D supplementation is effective in the reduction of blood pressure, including pregnancy-induced hypertension.
According to Michael Murray, author of the Encyclopedia of Natural Medicine, calcium supplementation appears to be very useful for reducing blood pressure in the elderly. Aside from supplementation, a diet high in fruits and vegetables and low in fat has also been shown to be helpful in lowering blood pressure and this may be attributed to the high mineral content of calcium, potassium and magnesium found in these foods.
Dairy sources have been acknowledged as calcium-rich but these foods are also high in phosphorous that prevent calcium from being absorbed. Non-dairy ,sources of calcium include almonds, fine bones in small fishes such as sardines, broccoli, cabbage, bok choy and dark green leafy vegetables. Small amounts of calcium are also present in some herbs and spices.
While there is no clear evidence to the role of calcium in lowering blood pressure, naturopathic doctors feel that calcium supplementation is safe and worth a try.
It may take six to eight weeks of supplementation to note any improvement. It is important that you do not reduce your anti-hypertensive medications but rather continue monitoring your blood pressure under the care of your practitioner.
There are several forms of calcium supplements available on pharmacy shelves and these vary in the chemical form and the amount of elemental calcium. Calcium carbonate is the most popular form as it is less expensive, but as pointed out by Michael Murray in his book, better results in reducing high blood pressure have been noted for calcium citrate than for calcium carbonate.
The University of Maryland recommends the calcium citrate form especially for older people and in particular postmenopausal women due to their low stomach acidity. Calcium should also be taken with magnesium and vitamin D for better absorption.