Low magnesium: what it does, who runs low and how much you need

Here's the calm, honest version: what magnesium does, who runs low and how much is enough.

What magnesium does in your body

Magnesium is a helper mineral for more than 300 enzyme systems ^[1]. It helps you:

• Turn food into energy
• Keep muscles and nerves working, including letting muscles relax after they contract
• Build protein, bone and DNA
• Regulate blood sugar and blood pressure as part of normal body function

Evidence: A — well-established roles ^[1].

Who tends to run low

Low intake is common. About 48% of Americans get less magnesium from food and drinks than their estimated average requirement (NHANES 2013–2016) ^[1]. That's intake, not blood levels.

Some people are more likely to run low ^[1]:

• Older adults, who often eat and absorb less and lose more through the kidneys. Teens and men over 70 have the lowest intakes.
• People with type 2 diabetes, who can lose more in urine.
• People with digestive conditions such as Crohn's or celiac disease, or past bowel surgery.
• People with alcohol use disorder.
• People on certain long-term medicines, like acid reducers called proton pump inhibitors (PPIs) and loop or thiazide diuretics ("water pills"). In 2011, the FDA warned that PPIs, usually taken over a year, can lead to low magnesium ^[1].

Signs worth asking your doctor about

Healthy kidneys hold on to magnesium when intake is low, so obvious problems are uncommon in healthy people ^[1].

Early signs are vague: poor appetite, nausea, tiredness and weakness. More serious deficiency can contribute to numbness, tingling, muscle cramps, abnormal heart rhythms and seizures ^[1]. Evidence: A.

These signs have many other causes. Testing is the only way to know, and even blood tests miss part of the picture, since less than 1% of your magnesium is in your blood ^[1].

How much you need

Most adults need 310–420 mg a day. Men need more than women ^[1].

The 350 mg upper limit (UL) covers magnesium from supplements and medicines only, not food. Healthy kidneys clear extra food magnesium ^[1]. The label Daily Value is 420 mg ^[4].

Foods with the most magnesium

Seeds, nuts, beans, soy and whole grains top the list. Many are low cost and plant-based ^[1][5].

Easy ways to add more:

• Pepitas on tacos or oatmeal
• Frijoles negros or rajma (kidney bean curry)
• Edamame or soymilk
• Peanut stew, palak (spinach) dishes or brown rice

Food first, then supplements

Start with food. If you and your doctor decide a supplement makes sense, here's what to know.

Forms. Labels list "elemental" magnesium, the amount of magnesium itself. In small studies, forms that dissolve well (citrate, aspartate, lactate, chloride) were absorbed better than oxide and sulfate ^[1]. Evidence: C. Good comparisons of glycinate, malate, taurate or L-threonate are limited.

Sleep. A 2021 review pooled 3 small trials in 151 older adults. People taking magnesium fell asleep about 17 minutes faster on average than with a placebo, but total sleep time didn't clearly change. The evidence was rated low to very low quality ^[2]. Evidence: C — limited. Individual results vary.

Too much. For anyone 9 and older, the UL for supplemental magnesium is 350 mg a day ^[1]. Higher doses often cause diarrhea, nausea and cramping, most often with oxide, carbonate, chloride and gluconate. Very large amounts, usually from laxatives or antacids, can be dangerous, especially with kidney disease ^[1]. If you have kidney problems, talk to your doctor first.

Interactions ^[1]:

• Bisphosphonates (alendronate): take at least 2 hours apart.
• Some antibiotics (doxycycline, ciprofloxacin): take them 2 hours before or 4–6 hours after magnesium.
• Diuretics: loop and thiazide types raise magnesium loss; potassium-sparing types reduce it.

Pregnant, breastfeeding or under 18? Check with your doctor or pharmacist before adding any supplement.

Where magnesium shows up in our products

• 13-in-1 Magnesium Complex: 500 mg magnesium per 2-capsule serving, from 13 forms including oxide, bisglycinate, citrate, malate, taurate, L-threonate and orotate, plus vitamin B6. The label lists 500 mg of magnesium itself (120% of the Daily Value), from 1,711 mg of magnesium compounds. That's above the 350 mg upper limit NIH sets for magnesium from supplements ^[1]. It also includes magnesium oxide, a form often linked to loose stools. Ask your doctor whether a full serving is right for you.
• Blood Sugar Complex: 250 mg of magnesium (as magnesium oxide) per serving.
• Gut Health: 90 mg of magnesium (as magnesium oxide) per serving.

Magnesium from every supplement counts toward the same 350 mg limit, so add them up.

Keep reading

• Your magnesium wind-down routine
• Steady energy and blood sugar routine
• Gut health routine
• Low vitamin B6
• Low vitamin D

Not sure where to start? Take the Sleep, stress and winding down quiz.

Questions people ask

Sources

1. NIH Office of Dietary Supplements. Magnesium fact sheet for health professionals, updated Jan 6, 2026.
2. Mah J, Pitre T. BMC Complement Med Ther, 2021.
3. American Academy of Sleep Medicine. Sleep Prioritization Survey 2024.
4. FDA. 21 CFR 101.9.
5. USDA. FoodData Central.