Coronary Artery Disease (CAD) and Angina and Magnesium

The mineral magnesium has actions in the body that resemble those of drugs in the calcium channel blocker family. Since these drugs are useful for angina, magnesium has been tried as well. Research evidence is very promising.

Magnesium has been called "nature's calcium channel blocker" because of its ability to block calcium from entering muscle and heart cells. Calcium-channel blockers work in a similar way, although much more powerfully. This is probably basis for some of magnesium's angina-relieving effects when it is taken as a supplement in fairly high doses.

Read more details about Magnesium.

In a 6-month, double-blind, placebo-controlled study, 187 individuals with angina were given either daily oral magnesium or placebo.¹⁷ The results showed that use of magnesium significantly improved exercise capacity, lessened exercise-induced chest pain, and improved general quality of life.

Similarly, two double-blind, placebo-controlled studies, enrolling a total of about 100 people with coronary artery disease found that supplementation with magnesium significantly improved exercise tolerance.^18,24

In the six-month trial mentioned above, subjects received magnesium at a dose of 730 mg daily.¹⁷

Note: Angina is a serious disease that absolutely requires conventional medical evaluation and supervision. No one should self-treat for angina. However, alternative treatments such as magnesium may provide a useful adjunct to standard medical care when monitored by an appropriate healthcare professional. Consult with your physician regarding magnesium dosage and specific safety issues.

• MD
• Clinical nutritionist or registered dietitian
• Naturopath

Safety Issues

The US government has set the following upper limits for use of magnesium supplements:

• Children

• 1-3 years: 65 mg

• 4-8 years: 110 mg

• Adults: 350 mg

• Pregnant or Nursing Women: 350 mg

In general, magnesium appears to be quite safe when taken at or below recommended dosages. The most common complaint is loose stools. However, people with severe kidney or heart disease should not take magnesium (or any other supplement) except on the advice of a physician. Maximum safe dosages have not been established for young children. There has been one case of death caused by excessive use of magnesium supplements in a developmentally and physically disabled child. ¹ Pregnant or nursing women should not exceed the nutritional dosages presented under Requirements/Sources .

If taken at the same time, magnesium can interfere with the absorption of antibiotics in the tetracycline family, ² and, possibly, the drug nitrofurantoin . ³ Also, when combined with oral diabetes drugs in the sulfonylurea family, magnesium may cause blood sugar levels to fall more than expected. ⁴

Interactions You Should Know About

If you are taking:

• Potassium supplements , manganese , loop and thiazide diuretics , oral contraceptives , estrogen-replacement therapy , cisplatin, digoxin , or medications that reduce stomach acid: You may need extra magnesium.

• Antibiotics in the tetracycline family or nitrofurantoin (Macrodantin): You should separate your magnesium dose from doses of these medications by at least 2 hours to avoid absorption problems.

• Oral diabetes medications in the sulfonylurea family (Tolinase, Micronase, Orinase, Glucotrol, Diabinese, DiaBeta): Work closely with your physician when taking magnesium to avoid hypoglycemia.

• Amiloride : Do not take magnesium supplements except on medical advice. ⁵

1. McGuire JK, Kulkarni MS, Baden HP. Fatal hypermagnesemia in a child treated with megavitamin/megamineral therapy. Pediatrics. 105(2):E18.
2. Tatro D, ed. Drug Interaction Facts. St. Louis, MO: Facts and Comparisons; 1999.
3. Naggar VF, Khalil SA. Effect of magnesium trisilicate on nitrofurantoin absorption. Clin Pharmacol Ther. 25(6):857-63.
4. Drug Evaluations Annual. Vol 2. Milwaukee, WI: American Medical Association; 1994.
5. Rudnicki M, Frölich A, Rasmussen WF, McNair P. The effect of magnesium on maternal blood pressure in pregnancy-induced hypertension. A randomized double-blind placebo-controlled trial. Acta Obstet Gynecol Scand. 70(6):445-50.

17. Shechter M, Bairey Merz CN, Stuehlinger HG, et al. Effects of oral magnesium therapy on exercise tolerance, exercise-induced chest pain, and quality of life in patients with coronary artery disease. Am J Cardiol. 2003;91:517-521.
18. Shechter M, Sharir M, Labrador MJ, et al. Oral magnesium therapy improves endothelial function in patients with coronary artery disease. Circulation. 2000;102:2353-2358.
24. Pokan R, Hofmann P, von Duvillard SP, et al. Oral magnesium therapy, exercise heart rate, exercise tolerance, and myocardial function in coronary artery disease patients. Br J Sports Med. 2006 Jul 6. [Epub ahead of print]