A registered dietitian who typically avoids recommending supplements now urges all patients to consider magnesium, citing its role in hundreds of bodily functions and growing evidence of widespread deficiency.
“I’m a supplement minimalist, but I’m also a realist,” says Tammy Karni, a functional nutrition specialist at Simply Nutrition in Houston. “The problem with magnesium is that our soils are depleted. So even if you have the best diet and great intentions to eat all the good sources of magnesium, the soils are depleted in minerals.”
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Magnesium Benefits Span Multiple Body Systems
The mineral’s impact extends far beyond the commonly known benefits for sleep and muscle function.
“Anything that spasms, twitches, is irritable or cramps is in total or in part associated with magnesium,” Karni explains. “It is involved in probably every organ in our body.”
Karni links magnesium deficiency to various health conditions, including:
Insomnia and sleep disorders
Cognitive decline
Depression and mood disorders
ADHD symptoms
Muscle spasms and cramps
Seizures and tremors
Tinnitus (ringing in the ears)
Heart arrhythmias
Digestive issues and constipation
Modern Lifestyle Depletes Magnesium Levels
Several everyday factors can decrease magnesium levels, according to Karni. These include:
Caffeine consumption
Alcohol intake
Drinking sodas (phosphorus depletes magnesium)
Stress
Highly processed diets
High sugar consumption
Certain medications (including antacids and diuretics)
Regular sauna use or heavy sweating
High calcium supplement intake
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Safe Dosage and Supplementation
Despite magnesium’s growing popularity, concerns about proper dosing persist. Karni recommends starting with 400 milligrams taken at night and says people can safely increase to 1,000 milligrams if needed.
“Some people need more,” she notes. “I go to the sauna every day, so I realized that I was not getting enough and went from 400 to 600 milligrams.”
Athletes and people who sweat heavily may require higher doses to maintain optimal levels.
Safety and Side Effects
While some worry about magnesium toxicity, called hypermagnesemia, Karni emphasizes that the risk is minimal for people with healthy kidney function.
“Your body gets rid of magnesium if you take too much,” she explains. “The problem of taking too much may be some digestive issues. It may cause diarrhea because it’s a muscle relaxant. So magnesium is called a relaxation mineral.”
Choosing the Right Form
Not all magnesium supplements are created equal. Karni advises avoiding magnesium carbonate and oxide, which aren’t well absorbed. Instead, she recommends magnesium glycinate as a good broad-spectrum option.
Different forms of magnesium target specific needs:
Magnesium glycinate: Best for cognitive function and mood
Magnesium threonate: Crosses the blood-brain barrier effectively
Magnesium malate: Targets muscle function
Magnesium thorate: Supports heart health
Food Sources Not Enough
While magnesium occurs naturally in many foods, Karni maintains that modern agricultural practices make it difficult to get adequate amounts through diet alone. However, these foods can help boost intake:
Cashews and almonds
Sunflower seeds
Whole grains
Beans
Quinoa
Leafy greens
Dark chocolate
Avocado
Testing for Deficiency
Traditional blood tests may not accurately reflect magnesium status.
“Only 1% of magnesium is in the blood. Ninety-nine percent is in tissue,” Karni explains. “Getting a blood test doesn’t tell you much. About 45% of Americans are depleted, and I think more than 90% of us are not getting enough in food, even if we’re trying to.”
Given the mineral’s broad impact on health and the low risk of overconsumption, Karni joins a growing number of health professionals who recommend magnesium supplementation for most adults.
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