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All About Calcium PDF Print E-mail

There are several important control mechanisms that are involved in calcium metabolism. This important mineral is vital to a large number of functions in the body including the transmission of nerve impulses; translation of hormone signals; blood clotting and muscle contraction.

The body essentially has three calcium stores:

1. Bones

2. Blood and the yellow fluid surrounding the blood cells (plasma)

3. Cells (Intracellular Fluid)

The balance of calcium between these stores depends on the balance between Vitamin D, calcitonin and parathyroid hormone. The thyroid gland produces calcitonin which works in unison with parathormone (PTH) from the parathyroid gland1. PTH converts vitamin D into an active hormone that helps to increase available calcium. PTH in turn stimulates the bones to give up calcium, while calcitonin puts the calcium back into the bones.

Vitamin D is important in the control of plasma calcium, particularly by controlling the absorption of calcium in the gut and resorption into the bones. As we know, bones are the body’s main pool of calcium and the general health of the bone cells, nutritional factors as well as the balance of the hormones that control calcium metabolism all determine how effectively calcium is deposited in the bones.

Osteoporosis is a generalised skeletal disorder characterised by the thinning of bone and deterioration of its architecture, causing susceptibility to fracture. Although calcium has long been recommended to prevent osteoporosis, there is little evidence to suggest that high calcium intake prevents fractures2. It is a known fact that the indigenous tribes in Africa consume an average of 400mg calcium per day; well below the recommended intake for post-menopausal; yet they have virtually no osteoporosis!

A big problem is negative calcium balance (where more calcium is lost than taken in) which results from metabolic and nutrition errors that negatively affect calcium metabolism often rendering it ineffective! Negative calcium (otherwise known as calcium dumping syndrome) is the failure to deposit calcium in the bones at an appropriate rate.

The result of this is that the calcium that should have been deposited into bone can only either be dumped or excreted. This often gives rise to the hardening of muscles and even internal organs. This is often a cause of severe back pain or a condition known as ‘frozen shoulder’.

The deposition of calcium in the bone matrix occurs under the influence of finely tuned steroid hormones the likes of oestrogen, progesterone and testosterone. However a ‘lack’ of these is unlikely to be the only cause of bone loss. Calcium-wasting factors in the lifestyle, which adversely affects the bone cells, are much more likely to be the cause. The drop in sex hormones is no more than a triggering factor which tends to get the blame, the real cause being calcium-wasting lifestyle factors. Some medical scientists now believe that a lifelong consumption of a high-protein, acid-forming diet may be a primary cause of osteoporosis.

Many aspects of our current lifestyle are potential contributors to negative calcium balance:

• Diets high in animal protein: Animal protein contributes to a condition known as acidosis (excess acid in the body). The body cannot tolerate substantial changes in acid level in the blood and neutralises this through two alkaline minerals namely calcium and sodium. When the body’s reserves of sodium are used up, calcium is taken from the bones. Therefore the more protein you eat, the more calcium you need. Due to animal protein’s high acid content, the kidney’s re-absorption of calcium is altered resulting in more calcium being excreted on a diet based on dairy, meat, chicken, fish and eggs. On the other hand, diets low in protein can also lead to bone loss, since nearly 50% of the bone volume consists of protein. This highlights the need for a well-balanced nutritious diet rich in seeds, nuts, fruits and vegetables.

• Excess sodium (salt) Intake: Every 100mmol of sodium takes 1mmol of calcium out of the body, which makes it a negative risk factor because it increases calcium loss.

• Dairy: Although dairy products have a high calcium content, they deplete the body of both calcium and magnesium. Calcium in milk is approximately 10 times higher than that of magnesium. Therefore, diets high in dairy are relatively magnesium-deficient. Since magnesium is necessary for regulating calcium metabolism, this lack becomes a problem. Pasteurised milk and dairy products no longer have the phosphatase enzyme which is necessary for the assimilation of calcium; furthermore the skimming, processing and homogenising further degrade calcium, making it even more difficult for the body to absorb. Dairy products have a high phosphorus-to-calcium ratio. Phosphorus draws calcium from the reserves in the bone and binds with calcium in the intestines resulting in poor absorption. As with meat, dairy is acid-forming and as mentioned above, the body then uses calcium from the bones to buffer the high acid content so that your blood pH remains constant. The problem with dairy is that it takes more calcium to buffer its acid content than what you actually get from the dairy.

• Excess Dietary Phosphorus: Many food sources contain phosphorus, including beef, soft drinks, preserved foods, yeast, bran, wheat-germ, dairy and various supplements. Excessive phosphorus binds to other essential trace minerals such as manganese, magnesium, copper and zinc, all of which are essential for calcium absorption. This disturbed calcium-to-phosphorus ratio may cause hyperparathyroidism in people3. This causes a loss of bone calcium and the excess parathyroid hormone also drives calcium into cells, such as the muscle cells in arteries, leading to arterial calcification4.

• High Alcohol Consumption: This causes calcium to leach out of the bones, creating a negative calcium balance.

• Chronic Heavy Metal Exposure: Mercury, lead, cadmium and aluminium found in our food, water, air and dental fillings all contribute to excess intracellular accumulation of calcium.

• Deficiency in Zinc, copper, magnesium, boron, manganese, silicon or chromium: All these minerals play an important role in calcium metabolism.

• Smoking: Contributes to high cadmium levels, which interferes with calcium metabolism.

• Chronic use of Drugs and Stimulants: Coffee, chocolate, diuretics, aspirin, laxatives and stimulants all interfere with calcium metabolism. Allopathic drugs that affect calcium are steroid therapy (cortisone), Depo-Provera and anti-epileptics.

• Antacids: Chronic use of antacids causing decreased stomach acidity can also impair the absorption of minerals such as calcium and has been linked to conditions such as osteoporosis! 5

• Lack of Oestrogen: Menopausal women are at a greater risk of gradual calcium loss of bones.

Imbalanced Bowel Flora and Inflamed Colon: An imbalance in gut flora and inflamed conditions of the colon wall adversely affect calcium absorption. In an impacted colon, the bacterial population becomes putrefactive and the bowel contents tend to become more alkaline. Alkalinity in the colon will further impair the absorption of calcium and other minerals.

How to get Calcium

Calcium supplements should be in the form of organic compounds, which cause the least disturbance to conditions in the digestive system and are better absorbed. Calcium carbonate (chalk) is used most extensively in supplements; however it does not promote the best levels of absorption and utilisation and has the disadvantage of neutralising some of the acid produced in the stomach. Dolomite, coral calcium and oyster shell are also not favourable. Calcium glycinate, acetate or citrate are the best forms to use. Calcium should always be given with magnesium, preferably in a 1:1 ratio. Magnesium is by far the most important mineral when it comes to bone loss.

Nutritional factors also play a role in the integrity of calcium. Fruits and vegetables supply the best source of absorbable calcium as they consist of all the necessary co-factors for calcium absorption and metabolism. Make sure that your diet is rich in broccoli, kale, okra, chick-peas, red kidney beans, green beans, watercress, apricots, figs, currants, oranges, almonds, Brazil nuts, hazelnuts, walnuts, sesame seeds, lentils, split-peas and quinoa6. Sardines and pilchards are a good source of calcium too provided that the small bones are eaten too.

In conclusion, a balanced wholefood diet is still the best solution. Limited amounts of organic dairy could form part of this diet, especially if you can get whole and unpasteurised milk from an authentic and reliable source. Fruits and vegetables which contain potassium and magnesium contribute the most to the maintenance of good bone density as does regular weight-bearing exercise which helps to strengthen the skeletal system.

 

References:

1. The Optimum Nutrition Bible. Patrick Holford.

2. Calcium, Dairy Products and Osteoporosis: Robert P. Heaney, MD, FACP, FAIN Journal of the American College of Nutrition, Vol. 19, No. 90002, 83S-99S (2000

3. Reduced dietary phosphate improves calcium balance in the ovariectomized rat. Bone, Volume 27, Issue

4, Page 40 4. The role of calcium and magnesium in the development of artherosclerosis. Orimo H; OuchiY, Depratment of Geriatrics, University of Tokyo, Japan.

5. Disease in Disguise: Carolee Bateson-Koch DC ND

6. International osteoporosis foundation www.iofbonehealth.org