HEALTHY BONES – Part 1
STRONTIUM for BONE HEALTH*
Strontium is a chemical element with symbol Sr, and atomic number 38. It is an alkaline earth metal. Nutritionally, it is referred to as a 'trace element'. Natural strontium is stable and is found in sea water and soil. Strontium is named after Strontian, a village in Scotland in the region where this mineral was first discovered in the ores taken from the lead mines. Strontium is chemically similar to calcium. Because of its extreme reactivity with oxygen and water, this element occurs naturally only in compounds with other elements, such as in the minerals strontianite and celestite.
Most people, when strontium is mentioned, think of strontium-90, a radioactive component of nuclear fallout, such as was produced during atmospheric testing of nuclear weapons in the 1950's. Strontium-90 (Sr90) is an isotope of strontium, with a half-life of 28.9 years. As a result of above ground nuclear testing, radioactive strontium spread throughout the environment and contaminated various foods, especially dairy products, and subsequently accumulated in the bones of both children and adults, leading in many cases to bone cancer.
Stable strontium (the subject of this newsletter), meaning non-radioactive, is non-toxic, even when administered in large doses for prolonged periods. Administration of stable strontium is the best way to eliminate radioactive strontium from the body. The stable form gradually replaces the radioactive form in bone, and the radioactive strontium is excreted in the urine.
Strontium is one of the most abundant elements on earth as well as being the most abundant trace element in sea water. The human body is said to contain approximately 320- 400mg of strontium, nearly all of which is in bone and connective tissue.
Strontium and Bones
Because strontium is chemically similar to calcium, strontium can replace calcium to some extent in various biochemical processes in the body, including replacing a small proportion of the calcium in the hydroxyapatite crystals of calcified tissues such as bones and teeth. This is its anabolic activity in bones. Strontium in these crystals imparts additional strength to bones and teeth. Strontium also appears to draw extra calcium into the bones. Rat studies have confirmed this.
Strontium and Osteoporosis
The human body absorbs strontium as if it were calcium. It tends to accumulate in bones, especially where active remodelling is taking place.
An editorial in the New England Journal of Medicine, January 29th 2004, discussed the following two studies.
In a three-year, randomised, double-blind, placebo controlled study using 680mg of strontium daily, women suffering from osteoporosis experienced a 41% reduction in risk of a vertebral fracture, compared to placebo. And overall vertebral density in the strontium group increased by 11.4%, in contrast there was a 1.3% decrease in the placebo group.
In a second study, 353 women who had suffered at least one vertebral fracture due to osteoporosis took varying levels of strontium medication or a placebo. The strontium dosage was 170mg, 340mg or 680mg per day. The women who took 680mg of strontium daily had an increase in lumbar bone mineral density of approximately 3% per year, significantly greater than placebo. By the second year of the study, there was a significant decrease in additional fractures in the strontium group compared to the placebo group. The authors concluded that the 680mg / day dose offered the best combination of efficacy and safety, and stated without equivocation that strontium (given as strontium ranelate) therapy increased vertebral bone mineral density and reduced the incidence of vertebral fractures. [2 gm/day of strontium ranelate provides 680mg of strontium.]
A further, larger study by the same research team (of the second study) involved 1,649 osteoporotic postmenopausal women. They received 680mg/day strontium (2 gm/day of strontium ranelate) or placebo for three years. The authors concluded that "treatment of postmenopausal osteoporosis with strontium ranelate leads to early and sustained reductions in the risk of vertebral fractures."
Several types of foods are rich in strontium.
340mg to 680mg per day.
Strontium is available as strontium carbonate, strontium chloride, strontium citrate and other salts as well as strontium ranelate. For example, 2194mg of strontium citrate supplies 680mg of elemental strontium, as does 2000mg (2grams) of strontium ranelate. Available from www.iherb.com.
It is recommended that the strontium supplement should not be taken at the same time as a calcium supplement, there should be at least a four-hour separation. This is because of the chemical similarity between strontium and calcium and the way they are absorbed and metabolised.
Strontium appears to offer a safe, effective and inexpensive approach to preventing and reversing osteoporosis and may be of benefit in other conditions (not discussed in this newsletter, but including osteoarthritis and the prevention of dental cavities). The optimum dose is 680 mg/day, although lower doses are clinically effective.
*Copyright 2012: The Huntly Centre.
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