An estimated 2% to 15% of Americans experience hypomagnesemia, a condition caused by a deficiency in magnesium (via StatPearls). Therefore, it’s not surprising that many people turn to magnesium-based supplements to meet their recommended daily intake. Magnesium is an essential nutrient that plays a role in blood sugar control, mental well-being, strong bones, reduced heart disease risk, and improved sleep. (There’s even evidence to support the idea that sleep quality may significantly improve when magnesium and melatonin are taken together.)
Speaking to NCPIC, Jonathan Stegall, M.D., an integrative oncologist in Atlanta, Georgia, provides additional clarity on why magnesium can help you sleep better, based on research. Stegall mentioned a 2022 systematic review of studies involving more than 7,500 adults, which yielded mixed results: “The observational studies showed a positive association between magnesium status and sleep quality, while the randomized controlled trials showed an uncertain relationship between magnesium and sleep,” he said. Two years later, a randomized controlled trial “found that magnesium-L-threonate improved sleep quality, especially deep sleep and REM sleep, as well as providing better energy, improved mood, improved productivity, and more alertness among adults.”
But what about magnesium and its supposed link to breast cancer risk? Stegall, the founder and medical director of The Center for Advanced Medicine, set the record straight: “Regarding magnesium and cancer risk, there is no good evidence to suggest that magnesium supplementation increases the risk of breast cancer.”
The potential link between magnesium and breast cancer: What we know
In a 2021 study published in the International Journal of Cancer, researchers examined whether a genetic predisposition to higher blood levels of 11 micronutrients was linked to breast cancer risk. After analyzing data from almost 123,000 women with breast cancer and nearly 106,000 women without breast cancer, the authors were only able to find such a connection with magnesium, but not with any of the other nutrients examined. That said, they stressed the need for more research before making any conclusions.
Similarly, a 2023 paper in BMC Medicine found a link between magnesium supplementation and increased breast cancer risk. However, as Stegall clarified, “Even the study author acknowledged that these results are not conclusive and more research needs to be done.”
“Currently, the bulk of the research suggests that magnesium helps protect against breast cancer,” stressed the integrative oncologist. “For starters, a magnesium deficiency possibly increases the risk of various cancers, including breast cancer.” Stegall also mentioned the results of a 2019 study published in Scientific Reports, in which researchers examined genetic markers and self-reported questionnaires from nearly 2,300 participants. As Stegall explained, the authors “found that women who supplement with magnesium have a lower risk of developing breast cancer.”
What to know about breast cancer risk and magnesium supplementation
The U.S. Centers for Disease Control and Prevention provides a list of breast cancer risk factors, which include increasing age (particularly after 50), early onset of menstruation (before age 12), late menopause (after age 55), inherited genetic mutations, a family history of breast or ovarian cancer, dense breast tissue, and exposure to radiation therapy before age 30. Meanwhile, avoidable risk factors include physical inactivity, post-menopausal obesity, certain types of hormone replacement therapy, the use of certain birth control pills, alcohol consumption, and smoking.
Of course, having one or more of these risk factors doesn’t necessarily mean that you’ll definitely get breast cancer. The best way to reduce your risk is to consult your doctor for guidance, whether for regular screening, identifying which foods to eat and to avoid for better breast health, or before introducing a magnesium-based supplement into your daily routine.
As Stegall cautioned, “Supplements are most helpful when addressing a known deficiency […] but many times, magnesium deficiency causes no symptoms at all. I recommend that patients ask their healthcare provider to measure magnesium in the blood.”
