Magnesium Supplementation Reduces Hot Flashes in Women with Breast Cancer

New study shows that magnesium supplementation may be effective and safe for breast cancer patients

By Michael T. Murray, ND

Printer Friendly PagePrinter Friendly Page


Park H, Parker GL, Boardman CH, Morris MM, Smith TJ. A pilot phase II trial of magnesium supplements to reduce menopausal hot flashes in breast cancer patients. Support Care Cancer. 2011;19(6):859-863.


Phase 2, open clinical trial


Twenty breast cancer patients (on average: 53.5 years; 8 on tamoxifen, 9 on aromatase inhibitors, 14 on antidepressants) experiencing at least 14 hot flashes each week

Study Medication and Dosage

Supplementation with magnesium oxide (400 mg/day for 4 weeks, increasing to 800 mg/d if needed, which occurred in 17 patients).

Outcome Measures

Prospective hot flash diary entry was used to collect data for 5 weeks of study period. Linear analog scale quality-of-life questionnaires, the symptom assessment scale (21 questions), and self-assessment scale (6 questions) questionnaires were used to assess quality of life during the study period. The hot flash score was defined as the product of the daily frequency and average hot flash severity.

Key Findings

Magnesium supplementation was found to be associated with a significant reduction in frequency of hot flashes (from 52.2 to 27.7/week, a 41.4% reduction, P =0.02) and hot flash score (from 109.8 to 47.8, a 50.4% reduction, P=0.04). More than half of patients were found to have greater than 50% reduction in hot flash score, and 76% were found to have greater than 25% reduction. Reductions in fatigue, sweating, and distress were all significant.

Practice Implications

Women who survive breast cancer often experience severe hot flashes as a result of anti-estrogen treatment, such as tamoxifen (Nolvadex®), and aromatase inhibitors including anastrozole (Arimidex®), exemestane (Aromasin®) and letrozole (Femara®). These hot flashes can be extremely uncomfortable and not amenable to usual treatments due to the concern about estrogenic activity of hormone replacement therapy as well as natural remedies like soy isoflavones and various herbal approaches. This new study shows that magnesium supplementation may be effective and is presumably a very safe therapy for these women. Side effects were minor: 2 women stopped the magnesium, 1 for headache and 1 for nausea, and 2 women had grade 1 diarrhea. Compliance was excellent, and many patients continued treatment after the trial.

Low magnesium levels may contribute to the development of hot flashes by making blood vessels more sensitive to hormonal changes or via influencing the serotonergic system in the brain.

The authors postulated that low magnesium levels may contribute to the development of hot flashes by making blood vessels more sensitive to hormonal changes or via influencing the serotonergic system in the brain. With supplemental magnesium, blood vessels may have become more stable, thereby eliminating the hot flash, or magnesium may have exerted some sort of central nervous system effect.

In addition to helping with hot flashes, correction of low magnesium status may have additional health benefits. Magnesium deficiency is extremely common in Americans, especially the elderly.1 In addition to the well-known association between low magnesium and increased risk for cardiovascular disease, low magnesium levels have also been linked to an increase in all cause mortality,2 Alzheimer’s disease,3 decreased muscle performance,4 insulin-resistance,5 and osteoporosis.6

About the Author

Michael T. Murray, ND, is President and CEO of Dr. Murray Natural Living and is Chief Science Officer for Enzymedica. Dr. Murray is a graduate, faculty member, and serves on the Board of Regents of Bastyr University, where he received his doctorate in Naturopathic Medicine. He is co-author of A Textbook of Natural Medicine and the Encyclopedia of Natural Medicine. He has also written over 30 other books including his latest book, The Magic of Food. For more information please visit


1. Durlach J, Bac P, Durlach V, Rayssiguier Y, Bara M, Guiet-Bara A. Magnesium status and ageing: an update. Magnes Res. 1998;11:25-42.

2. Reffelmann T, Ittermann T, Dörr M, et al. Low serum magnesium concentrations predict cardiovascular and all-cause mortality. Atherosclerosis. 2011 Jun 12. [Epub ahead of print]

3. Lemke MR. Plasma magnesium decrease and altered calcium/magnesium ratio in severe dementia of the Alzheimer type. Biol Psychiatry. 1995;37:341-343.

4. Dominguez LJ, Barbagallo M, Lauretani F, et al. Magnesium and muscle performance in older persons: the InCHI-ANTI study. Am J Clin Nutr. 2006;84:419.

5. Bo S, Pisu E. Role of dietary magnesium in cardiovascular disease prevention, insulin sensitivity and diabetes. Curr Opin Lipidol. 2008;19:50-56.

6. Kitchin B, Morgan SL. Not just calcium and vitamin D: other nutritional considerations in osteoporosis. Curr Rheumatol Rep. 2007;9:85-92.