Low magnesium is surprisingly common, and it rarely has a single cause. The recommended daily intake is 420 mg for men and 320 mg for women, but most people in Western countries fall short of that target. Your levels can drop because of what you eat, medications you take, or how your body handles magnesium internally. Often, it’s a combination of all three.
Most People Simply Don’t Get Enough
The most widespread reason for low magnesium is diet. Industrial food processing strips magnesium from many staple foods, and the shift toward highly processed Western diets has made this worse over the past several decades. In Spain, for example, roughly 75% of the population consumes less than 80% of the recommended magnesium intake. Similar patterns show up across Europe, the United States, and other industrialized countries.
Magnesium is concentrated in foods that many people don’t eat enough of: dark leafy greens, nuts, seeds, beans, and whole grains. Refined grains lose most of their magnesium during processing. If your diet leans heavily on white bread, processed snacks, and fast food, you’re likely running a daily deficit that compounds over time.
Medications That Drain Magnesium
Several common medications actively lower magnesium levels, sometimes significantly. If you take any of these, they may be the primary driver of your deficiency.
- Proton pump inhibitors (PPIs) like omeprazole and pantoprazole reduce your gut’s ability to absorb magnesium from food. These are among the most widely prescribed drugs in the world, used for acid reflux and ulcers, and long-term use is a well-established cause of low magnesium.
- Loop diuretics (water pills often prescribed for high blood pressure or heart failure) cause your kidneys to flush out extra magnesium in urine. Normally, your kidneys reabsorb magnesium to compensate for what you lose through digestion, but diuretics compromise that backup system.
- H2 blockers like famotidine also lower magnesium, though the effect is weaker than with PPIs.
- Metformin, the most common type 2 diabetes medication, can cause magnesium loss through the gastrointestinal tract.
If you’ve been on any of these for months or years, your magnesium stores may have gradually depleted even if your diet is reasonable.
Diabetes and Insulin Resistance
Type 2 diabetes and low magnesium feed each other in a vicious cycle. People with type 2 diabetes are roughly ten times more likely to have low magnesium than the general population.
Here’s how the cycle works: when blood sugar runs high, your kidneys excrete more magnesium in urine. High insulin levels do the same. So poorly controlled diabetes steadily drains your magnesium. At the same time, low magnesium impairs how your cells respond to insulin, making blood sugar harder to control. It does this by interfering with the signaling machinery on insulin receptors, reducing your cells’ ability to take in glucose. Low magnesium also disrupts insulin release from the pancreas itself, because magnesium is needed to regulate the ion channels that trigger insulin secretion.
The result is that diabetes worsens magnesium deficiency, and magnesium deficiency worsens diabetes. If you have insulin resistance or prediabetes, this connection is worth paying attention to early.
Other Common Causes
Alcohol is a potent magnesium drainer. It increases urinary magnesium loss and often goes hand in hand with poor dietary intake. Chronic heavy drinking is one of the most reliable predictors of magnesium deficiency.
Gastrointestinal conditions that cause chronic diarrhea, including Crohn’s disease, celiac disease, and short bowel syndrome, reduce the time your gut has to absorb magnesium from food. Even without a diagnosed condition, prolonged bouts of diarrhea or vomiting from any cause can drop your levels quickly.
Aging plays a role too. Magnesium absorption in the gut declines with age, while kidney excretion tends to increase. Older adults are also more likely to take the medications listed above, compounding the problem.
What Low Magnesium Feels Like
Mild magnesium deficiency often shows up as muscle cramps, twitching, or spasms, particularly in the legs and feet. You might also notice numbness or tingling in your hands and feet, fatigue that doesn’t improve with rest, or general weakness. Some people experience tremors or abnormal eye movements.
Severe deficiency is more dangerous. It can cause seizures, delirium, and abnormal heart rhythms. Dangerously low levels have the potential to trigger fatal cardiac arrhythmias. Most people won’t reach that point, but persistent mild symptoms are worth investigating rather than ignoring.
Why Your Blood Test Might Miss It
The standard blood test measures total serum magnesium, with a normal range of 1.7 to 2.2 mg/dL. The problem is that only about 1% of your body’s magnesium circulates in your blood. The rest is stored in bones, muscles, and soft tissues. Your body works hard to keep blood levels stable, pulling from those stores when needed. This means your serum level can look normal even when your total body magnesium is genuinely depleted.
If your blood test comes back in the low-normal range (say, 1.7 to 1.8 mg/dL) and you have symptoms, you may still benefit from increasing your intake. A result below 1.7 mg/dL confirms deficiency, but a result just above that line doesn’t necessarily rule it out.
Choosing the Right Supplement
Not all magnesium supplements are absorbed equally. Forms that dissolve well in liquid are more completely absorbed in the gut. Magnesium citrate, chloride, lactate, and aspartate all have better bioavailability than magnesium oxide or magnesium sulfate. Magnesium oxide is the cheapest and most common form on store shelves, but your body absorbs a smaller fraction of it.
If you’re supplementing to correct a deficiency, magnesium citrate or magnesium glycinate are popular choices that balance absorption, tolerability, and cost. Citrate can have a mild laxative effect at higher doses, which some people find helpful and others find inconvenient. Glycinate tends to be gentler on the stomach.
Food sources remain the most efficient way to maintain adequate levels long term. A quarter cup of pumpkin seeds delivers about 190 mg of magnesium. One cup of cooked spinach provides around 160 mg. Almonds, black beans, and dark chocolate are also rich sources. Building these into your regular diet addresses the underlying gap that supplements can only patch.