Magnesium Supplements Crash Course: Benefits and Side Effects

Suddenly, everyone is obsessed with magnesium supplements. It’s the key ingredient in #sleepygirlmocktails, powders stirred into tart cherry juice and prebiotic soda, a wellness cocktail for anxious millennials. Your coworkers are popping magnesium glycinate before bed instead of melatonin, because it allegedly cures insomnia, constipation, and existential dread. Folks seem especially concerned with optimizing their poop and pillow time. In the past year, Google searches for “which magnesium is best for sleep” and “which magnesium makes you poop” have more than doubled.

Magnesium is essential for maintaining a healthy cardiovascular system. It’s also one of the most abundant minerals in the human body, running more than 300 biochemical reactions, from protein synthesis to nerve function and blood sugar regulation. It supports bone structure and helps shuttle calcium and potassium across cell membranes, a process that allows for muscle contractions and normal heart rhythms.

You can get it from foods like legumes, leafy vegetables, and whole grains, or from fortified foods and dietary supplements. The question is: Do you need to supplement?

Symptoms of Magnesium Deficiency

While an essential mineral for overall health, many people don’t get enough magnesium. This is partly because magnesium is predominantly found in high-fiber foods, and a significant portion of Americans do not consume sufficient fiber, according to registered dietitian Sue-Ellen Anderson-Haynes. Research confirms this: More than 90 percent of women and 97 percent of men fail to meet the recommended daily intake for dietary fiber.

Older adults are particularly at risk, as the body’s ability to absorb magnesium decreases with age. Health conditions like Crohn’s disease or kidney disease, alcohol use disorder, and the use of diuretics can all lead to magnesium depletion.

Anderson-Haynes notes that a magnesium deficiency (also known as hypomagnesemia) can result in a range of symptoms, such as headaches, nausea, constipation, tremors, heart palpitations, and muscle soreness. Chronic magnesium deficiency can increase the risk of developing high blood pressure, osteoporosis, insulin resistance, and type 2 diabetes.

Benefits of Magnesium Supplements

There are several forms of magnesium supplements, including:

• Magnesium citrate: Often taken as a remedy for occasional constipation.
• Magnesium glycinate: Often taken for better sleep and reduced anxiety.
• Magnesium oxide: Often taken for constipation or indigestion.
• Magnesium l-threonate: Often taken for better sleep, cognitive function, and reduced stress.
• Magnesium chloride: Often taken as an electrolyte replenisher and for its laxative effect.

Supplements are most useful for people with a confirmed deficiency, but early research suggests possible benefits for specific conditions, including migraines, insomnia, and cardiovascular disease.

“It’s really overlooked that magnesium can help with menstrual cycle irregularity in terms of making sure that you’re not having severe cramping,” says Anderson-Haynes, who adds it may also benefit women in perimenopause and menopause. Clinically, it may be part of the treatment for pregnancy complications like preeclampsia and eclampsia.

Can You Take Too Much?

The recommended dietary allowance is 320 milligrams per day for women and 420 milligrams per day for men. These are amounts most people can reach with a balanced diet; healthy kidneys regulate magnesium levels, excreting excess when magnesium intake is high and conserving it when it’s low.

Daily supplements under 350 milligrams are generally considered safe for healthy adults. “If you take too much magnesium, you’ll probably get diarrhea, because it loosens the bowels,” Anderson-Haynes says. Other side effects include nausea, gastrointestinal discomfort, and, at very high levels of magnesium (usually from overusing laxatives or antacids), low blood pressure, muscle cramps, breathing problems, and, in rare cases, cardiac arrest. People with kidney disease are at the highest risk of toxicity.

Should You Supplement?

For most healthy adults, magnesium supplements aren’t essential. If you struggle with migraines, insomnia, or other conditions where research suggests health benefits, they may be worth trying—but first talk to a health care professional.

Otherwise, focus on magnesium-rich foods. These include but are not limited to: legumes (beans, lentils, chickpeas), leafy greens (artichokes, kale, spinach), whole grains (oats, barley, quinoa), nuts (almonds, cashews, peanuts), fruit (bananas, avocado, dried apricots), and soy products (tofu, soy milk, edamame).

If you do decide to take any dietary supplements, “look for a seal or certification that says GMP (Good Manufacturing Practices) or NSF,” says Anderson-Haynes, stressing the importance of third-party tests and verifications, considering the FDA doesn’t regulate dietary supplements in the US.

Meet the Experts

• Sue-Ellen Anderson-Haynes, MS, RDN, CDCES, is a spokesperson for the Academy of Nutrition and Dietetics and founder of 360Girls&Women.

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