In 2011 the NIH reported that approximately 43% of the U.S. population (including almost 70% of older women) use dietary supplements containing calcium. What’s not said is that without balancing their calcium with proper amounts of magnesium, they may be at risk.

There is a growing amount of scientific evidence pointing to high calcium–low magnesium intake leading to calcification, or hardening, of arteries (atherosclerosis—the number one cause of death in the US), osteoporosis and osteoporotic bone fractures. A 2011 British Medical Journal study showed a higher risk of heart disease and stroke in women taking calcium supplements.

Most people, and the majority of MDs, do not understand certain key facts about calcium and its sister mineral, magnesium:

• Typically, less than half of calcium intake is actually absorbed in the gut. Of the remainder, some is excreted (but causes constipation on the way out), and the rest helps to form kidney stones, gallstones, heel spurs, atherosclerotic plaque in artery walls, and breast calcifications.

• Magnesium stimulates the hormone calcitonin, which helps to preserve bone structure and draws calcium out of the blood and soft tissues back into the bones, all the while lowering the likelihood of osteoporosis, some forms of arthritis, heart attack and kidney stones.

• Adequate levels of magnesium are essential for the absorption and metabolism of calcium and vitamin D. Magnesium actually converts vitamin D into its active form.

• Recommendations for calcium intake vary greatly. In the United States, adults are told to take 1,000 mg per day and women over 50 are told to take up to 1,500 mg. In the United Kingdom, the RDA is 700 mg daily, while the World Health Organization recommends only 400–500 mg.

Often supplementation is taken without consideration for the amount of calcium in the diet both from food sources and from water (some tap and mineral waters). Many people, especially those consuming dairy products, have high-calcium diets. This can lead to a greater amount of unabsorbed calcium unopposed by magnesium.

The commonly accepted ratio of 2:1 calcium to magnesium found in many cal-mag supplements traces back to the French scientist Dr. Jean Durlach, who stipulated the 2:1 ratio as an outermost not-to-be-exceeded level when considering calcium intake from all sources (food, water and supplements). This has been largely misunderstood and has been taken instead as an outright recommendation.

The fact that most people do not get their minimum daily requirement of magnesium exacerbates the situation. The high calcium–low magnesium diet of most Americans when coupled with calcium supplementation can give a Ca to Mg imbalance of 4: or 5:1 or higher, which constitutes a walking time bomb of impaired bone health, compromised muscles and nerves, and heart disease.

Magnesium is a "safer" product than calcium because it is excreted more completely and doesn’t build up in the body. Most people can supplement with magnesium citrate powder orally and get positive results. The easily obtainable Natural Calm is the one I recommend. Building up to 300 mg twice a day is a good treatment dose, and sipping it in water throughout the day keeps it from causing any laxative effects.

The only people who should avoid self-administering of magnesium are those with heart block (the type that requires a pacemaker), myasthenia gravis (because their muscles are already too relaxed), bowel obstruction, and people on kidney dialysis.

For more critical information on the subject of magnesium, visit the nonprofit educational resource site at www.nutritionalmagnesium.org.

Carolyn Dean, MD, ND, is the medical director of the Nutritional Magnesium Association and the author of The Magnesium Miracle.

Online 3/23/12