Quick Answer: Magnesium glycinate is best for most people—it's highly absorbable (up to 80%), gentle on the stomach, and helps with sleep and anxiety. Magnesium citrate is good if you also want digestive regularity. Magnesium L-threonate is best specifically for brain health. Avoid magnesium oxide—it's cheap but only 4% absorbed. Take 200-400mg daily.
Walk into any vitamin aisle and you'll find a dozen different magnesium supplements: glycinate, citrate, oxide, threonate, malate, taurate... the list goes on. With so many options, it's hard to know which one actually works for YOUR needs.
Here's the thing: the form of magnesium matters A LOT. Some forms absorb 20x better than others. Some are great for sleep while others will keep you running to the bathroom. Let me break down exactly which type you should take.
Magnesium Types Comparison Chart
| Type | Absorption | Best For | Side Effects |
|---|---|---|---|
| Glycinate | High (80%) | Sleep, anxiety, daily use | Minimal |
| Citrate | Medium (25-30%) | Constipation, general | Mild laxative |
| L-Threonate | High | Brain, memory, cognition | Minimal |
| Malate | Medium | Energy, muscle pain | Minimal |
| Taurate | Medium | Heart health | Minimal |
| Oxide | Very Low (4%) | Constipation only | Strong laxative, cramping |
Magnesium Glycinate: Best Overall Choice
Best for: Sleep, anxiety, stress, muscle relaxation, daily supplementation
Magnesium glycinate is magnesium bound to glycine, an amino acid that's calming on its own. This creates a double benefit: you get the magnesium AND the relaxation effects of glycine.
Why Glycinate Stands Out
- Highest absorption: Up to 80% bioavailability
- No digestive issues: Won't cause loose stools or cramping
- Calming effects: Glycine supports GABA (relaxation neurotransmitter)
- Great for sleep: Research shows it improves sleep quality
- Reduces anxiety: Studies link it to lower cortisol and stress
When to Take
For sleep: 200-400mg 30-60 minutes before bed
For general health: Split dose morning and evening
Top Pick: Doctor's Best High Absorption Magnesium Glycinate—affordable, well-absorbed, and third-party tested.
Magnesium Citrate: Good for Digestion
Best for: Constipation relief, general supplementation (if you tolerate it)
Magnesium citrate is bound to citric acid. It absorbs reasonably well (25-30%) and has a mild laxative effect that some people actually want.
Pros and Cons
- Pro: Decent absorption (much better than oxide)
- Pro: Helps with constipation
- Pro: Relatively affordable
- Con: May cause loose stools
- Con: Not ideal before bed (bathroom trips)
When to Choose Citrate
Pick citrate if you deal with constipation and want a two-in-one benefit. Avoid if you have IBS-D or loose stools.
Magnesium L-Threonate: Best for Brain
Best for: Memory, cognitive function, brain fog, focus
Magnesium L-threonate (often sold as Magtein®) is the only form proven to cross the blood-brain barrier and increase brain magnesium levels. Developed at MIT, it's specifically designed for cognitive benefits.
Why It's Unique
- Crosses blood-brain barrier: Most forms don't reach the brain effectively
- Improves memory: Studies show benefits for learning and recall
- Supports neuroplasticity: May help brain adaptability
- May help anxiety: By supporting brain magnesium levels
The Downside
L-threonate is expensive and contains less elemental magnesium per dose. You may need to take multiple capsules for full benefit.
Best For: Students, professionals, older adults concerned about cognitive decline, or anyone with brain fog.
Magnesium Malate: Best for Energy
Best for: Energy production, muscle pain, fibromyalgia
Magnesium malate combines magnesium with malic acid, which plays a role in the energy production cycle (Krebs cycle). It's popular among those with chronic fatigue or muscle pain conditions.
Benefits
- Supports ATP production (energy)
- Good absorption
- May help with muscle soreness and fibromyalgia
- Gentle on stomach
Magnesium Oxide: Avoid for Supplementation
Not recommended: Only 4% absorption rate—nearly worthless as a supplement
Magnesium oxide is the most common form in cheap supplements because it's inexpensive. Unfortunately, your body absorbs almost none of it.
Why Oxide Is Problematic
- Only 4% absorbed: 96% passes straight through
- Strong laxative effect: That's where all the unabsorbed magnesium goes
- Can cause cramping: Draws water into intestines
- Waste of money: You're essentially buying an expensive laxative
The only legitimate use for magnesium oxide is as an occasional laxative. For actual magnesium supplementation, choose glycinate, citrate, or threonate.
How Much Magnesium Should You Take?
Daily Recommendations
- RDA: 310-420mg for adults (from all sources)
- Supplemental dose: 200-400mg daily
- Upper limit: 350mg from supplements (higher may cause diarrhea)
Important: Check the "elemental magnesium" on labels. A 500mg magnesium glycinate capsule may only contain 100mg of actual magnesium. The rest is the glycine carrier.
Signs You Need More Magnesium
- Muscle cramps or twitches
- Poor sleep quality
- Anxiety or stress sensitivity
- Fatigue
- Headaches or migraines
- Constipation
Which Magnesium by Condition
| Condition/Goal | Best Form |
|---|---|
| Sleep problems | Glycinate or Threonate |
| Anxiety/stress | Glycinate |
| Constipation | Citrate |
| Brain fog/memory | L-Threonate |
| Muscle cramps | Glycinate or Malate |
| Energy/fatigue | Malate |
| Heart health | Taurate |
| General daily use | Glycinate |
| Migraines | Glycinate or Citrate |
Top Product Recommendations
Best Magnesium Glycinate
- Doctor's Best High Absorption: Best value, well-tolerated
- Pure Encapsulations: Premium quality, hypoallergenic
- NOW Foods: Budget-friendly, effective
Best Magnesium L-Threonate
- Life Extension Neuro-Mag: Uses Magtein® brand
- Double Wood Supplements: Good value alternative
Best Magnesium Citrate
- Natural Vitality Calm: Popular powder form, tastes good
- Thorne Magnesium CitraMate: Premium quality
The Bottom Line
- Best overall: Magnesium glycinate (sleep, anxiety, daily use)
- Best for brain: Magnesium L-threonate
- Best for constipation: Magnesium citrate
- Best for energy: Magnesium malate
- Avoid: Magnesium oxide (barely absorbed)
- Dose: 200-400mg elemental magnesium daily
For most people, magnesium glycinate is the safest bet. It absorbs well, doesn't cause digestive issues, and provides the calming benefits most people are looking for. Start with 200mg and increase as needed.
Disclaimer: This article is for informational purposes only. Consult a healthcare provider before starting supplements, especially if you have kidney disease, heart conditions, or take medications.