Bone Health : Calcium Intake Without Magnesium Is A Health Risk

By Carolyn Dean, MD, ND

Medical Director, Nutritional Magnesium Association
Author, The Magnesium Miracle.

Approximately 43 percent of the US population (including almost 70 percent of older women) use dietary supplements containing calcium.1. Without balancing their calcium with magnesium, they may be at risk.

Most people, including 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 absorbed in the gut,2 the rest either being excreted or potentially forming kidney stones or being transported to soft tissues where it can harden (calcify).
  • Adequate levels of magnesium are essential for the absorption and metabolism of calcium and vitamin D.

  • Magnesium converts vitamin D into its active form so that it can aid calcium absorption. Magnesium also stimulates the hormone calcitonin, which helps to preserve bone structure and draws calcium out of the blood and soft tissues back into the bones, lowering the likelihood of osteoporosis, some forms of arthritis, heart attack and kidney stones.3,4,5,6,7,8,9.10

  • 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.11,12,13

  • Recommendations for calcium intake vary greatly. In the US, 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.

The key to calcium-magnesium balance is at a cellular level. The effectiveness and benefits of calcium with respect to bone health and the prevention of osteoporosis are enormously impaired in the absence of adequate levels of magnesium in the body.

If we consume too much calcium without sufficient magnesium, not only will we create stress within the body but the excess calcium will not be utilized correctly and may become toxic. Magnesium keeps calcium dissolved in the blood. Too much calcium and too little magnesium can cause some forms of arthritis, kidney stones, osteoporosis and calcification of the arteries, leading to heart attack and cardiovascular disease.14

The commonly agreed-upon ratio of 2:1 calcium to magnesium found in many cal-mag supplements traces back to the French scientist Dr. Jean Durlach,15 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 is taken as a recommendation of a 2:1 calcium-to-magnesium imbalance.

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 and heart disease.

Medical doctors aren’t telling patients about magnesium because we didn’t learn about necessary nutrient supplementation in medical school. I thank my naturopathic training for educating me in this regard. Instead, most doctors only prescribe calcium to the exclusion of other nutrients, leading to an epidemic of calcium build-up diseases over the past decade and more magnesium deficiency.

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 only people who should avoid self-administering 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.

It is difficult to get enough magnesium through diet to even meet the minimum RDA requirements. It has been farmed out of the soil and eliminated from most processed foods. I recommend monitoring dietary calcium intake, supplementing with vitamin D3, getting the minimum daily requirement of magnesium, “and going for a 1:2 or at least a 1:1 calcium-magnesium balance.”

For more critical information on the subject of magnesium, visit the non-profit educational resource site at


1. National Institutes of Health, Office of Dietary Supplements. 2011. Dietary Supplement Fact Sheet: Calcium. “Calcium Intakes and Status.” 2. See reference 1 above.
3. Zofková I, , Kancheva RL. The relationship between magnesium and calciotropic hormones. Magnes Res. 1995 Mar; 8 (1): 77-84.
4. Zofková I, , Kancheva RL. The relationship between magnesium and calciotropic hormones. Magnes Res. 1995 Mar; 8 (1): 77-84.
5. Carpenter, T. O. Disturbances of vitamin D metabolism and action during clinical and experimental magnesium deficiency. Magnes Res. 1988 Dec; 1 (3-4): 131-9.
6. Saggese, G. Bertelloni, S. Baroncelli, G. I. Federico, G. Calisti, L. Fusaro, C. Bone demineralization and impaired mineral metabolism in insulin-dependent diabetes mellitus. A possible role of magnesium deficiency. Helv Paediatr Acta. 1989 Jun; 43 (5-6): 405-14.
7. McCoy, H. Kenney, M. A. Interactions between magnesium and vitamin D: possible implications in the immune system. Magnes Res. 1996 Oct; 9 (3): 185-203.
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10. Ramon Medalle, MD, Christine Waterhouse, MD and Theodore J. Hahn, MD Am, J. Clin Nutr. 29:854-858, 1976
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13. BMJ. 2011;342:d2040. Epub 2011 Apr 19. PMID: 21505219
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