Magnesium UK Guide: Best Forms, Doses & Top Products
Last updated: 2026-08-31 · by Sun Supplements
Magnesium is the UK's most-searched supplement — and the one with the most confusion. Glycinate, citrate, L-threonate, malate: which form should you actually take? How much, when, and for what goal? This guide answers all of it.
UK #1 search
Most-searched supplement
4 main forms
Glycinate, citrate, L-threonate, malate
Sleep & relaxation
The most common reason UK buyers take it
£8-£25
Typical 1-3 month supply
Why magnesium is the UK's #1 supplement
Magnesium is the most-searched supplement in the UK — and for good reason. Modern UK diets are widely estimated to be magnesium-deficient: refined grains, processed foods, and low intake of leafy greens mean most UK adults get well below the UK daily target of 300 mg for men and 270 mg for women. Add in alcohol, stress, and intense exercise (all of which deplete magnesium), and a UK adult's true magnesium requirement is often higher than what's delivered by diet alone.
Magnesium is involved in over 600 enzymatic reactions in the body — including energy production, muscle and nerve function, blood glucose control, blood pressure regulation, and sleep. Symptoms of low magnesium include muscle cramps, fatigue, poor sleep, anxiety, irritability, and (in severe cases) cardiac arrhythmia. UK buyers commonly take magnesium to address:
- Poor sleep — magnesium glycinate supports sleep onset and sleep quality
- Muscle cramps and tension — magnesium supports muscle relaxation
- Anxiety and stress — magnesium glycinate has calming effects via GABA modulation
- Exercise recovery — magnesium supports ATP production and reduces post-exercise soreness
- Menstrual cramps — magnesium may reduce period pain and PMS
- Migraine prevention — high-dose magnesium (400-600 mg/day) is supported by clinical evidence
Forms of magnesium compared
Not all magnesium is equal. The form (or "salt") determines absorption, tolerability, and intended use. The four forms UK buyers should know about:
| Form | Elemental Mg | Best for | Notes |
|---|---|---|---|
| Magnesium glycinate (bisglycinate) | ~14% | Sleep, anxiety, gentle on stomach | Most popular UK choice. No laxative effect. Calmative. |
| Magnesium citrate | ~16% | Constipation, general use | Better absorbed than oxide. Mild laxative effect at higher doses. |
| Magnesium L-threonate (MagMind) | ~8% | Cognition, memory, brain fog | The only form proven to cross the blood-brain barrier. Patented. |
| Magnesium malate | ~15% | Energy, muscle pain, fibromyalgia | Well-absorbed, gentle on stomach, supports cellular energy. |
Forms to avoid: magnesium oxide (poorly absorbed, ~4% elemental Mg, strong laxative effect), magnesium carbonate (anti-acid, low absorption), magnesium sulphate (Epsom salts — bath use only).
Glycinate vs citrate — the UK buyer's choice
The most common question from UK buyers: glycinate or citrate? In short: glycinate for sleep, anxiety, and daily use; citrate for occasional constipation or general magnesium support. Glycinate has a higher calming effect; citrate is more bioavailable on a per-gram basis but more likely to cause loose stools at higher doses.
L-threonate — the cognitive form
Magnesium L-threonate (patented as MagMind) is the only form shown in published clinical trials to raise brain magnesium levels. The 2026 evidence base supports its use for memory, focus, and age-related cognitive decline. It's more expensive than glycinate but worth it if cognition is your primary goal.
How much magnesium do you need
The UK Reference Nutrient Intake (RNI) for magnesium is 300 mg/day for men and 270 mg/day for women. Supplementation typically ranges from 200 to 400 mg of elemental magnesium per day. Most UK supplement labels state the elemental magnesium content on the front — check this rather than the total magnesium compound weight.
For specific goals:
- General health: 200-300 mg/day
- Sleep: 200-400 mg glycinate, taken 30-60 minutes before bed
- Muscle cramps: 300-400 mg/day, split across two doses
- Exercise recovery: 300-400 mg/day
- Migraine prevention: 400-600 mg/day (consult your GP if you have a diagnosed migraine condition)
When to take magnesium
Magnesium can be taken at any time of day. For sleep support, take it 30-60 minutes before bed. For exercise recovery, take it post-workout or with your evening meal. For general health, split the dose (morning + evening) to maintain steadier blood levels and reduce any stomach upset.
Magnesium competes with calcium for absorption, so if you also take calcium, separate them by 2-3 hours.
Taking magnesium with food
All forms of magnesium are better absorbed when taken with food. The one exception is magnesium citrate, which can be taken on an empty stomach for a more pronounced effect on bowel regularity.
Avoid taking magnesium at the same time as:
- Antibiotics (especially tetracyclines and quinolones) — magnesium binds to them and reduces absorption. Take 2-3 hours apart.
- Bisphosphonates (osteoporosis medication) — same binding issue.
- Iron supplements — they compete for absorption.
Top UK products
The most popular magnesium products with Sun Supplements UK buyers:
- NOW Foods Magnesium Glycinate 400 mg — 90 tablets, best-value glycinate. ~£10 for 3 months.
- Solaray Magnesium Glycinate 400 mg — 120 veg caps, vegan-friendly.
- Swanson Magnesium Glycinate Powder — 300 g, great for mixing into water or smoothies.
- Swanson Triple Magnesium Complex — blend of glycinate + citrate + malate, 120 caps.
- Solgar Magnesium Citrate — 60 tablets, premium heritage brand.
Frequently asked questions
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