Magnesium is involved in more than 300 enzyme reactions in the body, from making energy and protein to controlling muscle contraction, nerve signals, blood sugar and blood pressure. Surveys suggest many adults eat less than they need. If you have looked at supplements, you have probably noticed a confusing range of forms: glycinate, citrate, oxide, threonate and more. This guide explains the types of magnesium, their benefits and how to choose.
How much magnesium do you need?
| Group | Recommended daily amount |
|---|---|
| Men 19–30 | 400 mg |
| Men 31+ | 420 mg |
| Women 19–30 | 310 mg |
| Women 31+ | 320 mg |
| Pregnancy | 350–360 mg |
Types of magnesium compared
| Form | Absorption | Commonly used for | Notes |
|---|---|---|---|
| Magnesium glycinate (bisglycinate) | Good | General supplementation, relaxation, sleep support | Gentle on the stomach; least likely to cause diarrhea |
| Magnesium citrate | Good | Constipation, general use | Mild laxative effect at higher doses |
| Magnesium oxide | Low | Constipation, heartburn; used in migraine studies | High magnesium content per pill but poorly absorbed |
| Magnesium chloride | Good | General use; also in topical sprays | Topical absorption is not well proven |
| Magnesium malate | Good | General use, muscle aches | Limited specific research |
| Magnesium L-threonate | Good | Brain health and memory | Crosses into the brain in animal studies; human evidence is early |
| Magnesium taurate | Good | Heart and blood pressure support | Mostly animal research so far |
| Magnesium sulfate | Low orally | Epsom salt baths; hospital IV use | Not recommended as an oral daily supplement |
Which type of magnesium should you choose?
- For general daily use or a sensitive stomach: glycinate.
- For constipation: citrate or oxide.
- For sleep and relaxation: glycinate is the most popular choice, though evidence for sleep benefits is limited and strongest in older adults with low intake. Pair it with good habits from our guide on falling asleep faster.
- For migraine prevention: discuss with your doctor; most studies used around 400–600 mg of magnesium oxide or citrate, which is above the self-supplementation limit.
Evidence-based benefits of magnesium
- Blood pressure: meta-analyses show modest reductions, especially in people who are low in magnesium. See normal blood pressure by age.
- Blood sugar: higher magnesium intake is linked to a lower risk of type 2 diabetes, and supplements may improve insulin sensitivity in people who are deficient.
- Migraine: neurology guidelines rate magnesium as “probably effective” for preventing migraines.
- Constipation: some forms draw water into the bowel and act as gentle laxatives.
- Bone health: magnesium is needed to activate vitamin D. Learn more in our guide to vitamin D deficiency.
Signs of low magnesium
Early signs can include loss of appetite, nausea, fatigue and weakness. More significant deficiency can cause muscle cramps and twitches, numbness, tingling and abnormal heart rhythms. Blood tests are not perfect, because most magnesium is stored in bones and cells. People at higher risk include those with type 2 diabetes, digestive diseases, alcohol use disorder, older adults and people taking long-term proton pump inhibitors or certain diuretics.
Best food sources of magnesium
| Food | Serving | Magnesium |
|---|---|---|
| Pumpkin seeds, roasted | 1 oz (28 g) | 156 mg |
| Chia seeds | 1 oz (28 g) | 111 mg |
| Almonds | 1 oz (28 g) | 80 mg |
| Spinach, boiled | ½ cup | 78 mg |
| Cashews | 1 oz (28 g) | 74 mg |
| Dark chocolate (70–85%) | 1 oz (28 g) | about 65 mg |
| Black beans, cooked | ½ cup | 60 mg |
| Avocado | 1 cup, cubed | 44 mg |
Many of these are also high-fiber foods, so you get a double benefit.
Side effects and safety
- The most common side effects are diarrhea, nausea and stomach cramps, especially with citrate, oxide and chloride.
- People with kidney disease should not take magnesium supplements without medical advice, as the kidneys may not clear excess magnesium.
- Magnesium can reduce absorption of some antibiotics (tetracyclines and quinolones) and osteoporosis drugs (bisphosphonates). Take them at least 2 hours apart, and check with your pharmacist.
- Very high doses can cause dangerously high magnesium levels, with low blood pressure, confusion and irregular heartbeat.
Frequently asked questions
Is it better to take magnesium in the morning or at night?
Either works. Many people take glycinate in the evening as part of a wind-down routine. Taking it with food may reduce stomach upset.
Can I take magnesium every day?
For most healthy adults, a daily supplement within the 350 mg limit is considered safe. Focus on food first.
Do Epsom salt baths raise magnesium levels?
There is little good evidence that meaningful amounts are absorbed through the skin. A warm bath can still be relaxing.
Medical disclaimer: This article is for general education only and is not a substitute for personal medical advice. Talk to your doctor or pharmacist before taking magnesium, especially if you have kidney disease or take prescription medication.
