Magnesium is the fourth most abundant mineral in the human body and involved in over 300 enzymatic reactions. It is also one of the most commonly supplemented — but the form of magnesium matters enormously. The cheap oxide form found in most supermarket supplements has approximately 4% bioavailability. The glycinate form has approximately 80% bioavailability. That is a 20-fold difference, which explains why many people who have “tried magnesium” and noticed nothing were likely taking the wrong form.
Magnesium forms ranked by quality and use case
| Form | Bioavailability | Best for | Price tier |
|---|---|---|---|
| Magnesium glycinate / bisglycinate | ⭐⭐⭐⭐⭐ ~80% | Sleep, anxiety, muscle relaxation | Mid-premium |
| Magnesium malate | ⭐⭐⭐⭐ ~70% | Energy, fibromyalgia, exercise recovery | Mid |
| Magnesium taurate | ⭐⭐⭐⭐ ~70% | Cardiovascular, blood sugar, brain | Mid-premium |
| Magnesium citrate | ⭐⭐⭐ ~50% | General supplementation, constipation | Budget-mid |
| Magnesium l-threonate | ⭐⭐⭐⭐ High (crosses BBB) | Cognitive function, memory | Premium |
| Magnesium oxide | ⭐⭐ ~4% | Constipation (short-term only) | Budget |
Top 5 magnesium supplements UK
- Lily & Loaf Triple Magnesium — glycinate + malate + taurate; broadest coverage in one product; 90-day guarantee
- Pure Encapsulations Magnesium Glycinate — highest quality single-form glycinate; used by integrative practitioners; premium price
- Lily & Loaf Double Magnesium — sleep-focused two-form formula; excellent for sleep and relaxation specifically
- Nature’s Best Magnesium Bisglycinate — good single-form glycinate at mid price; reliable UK brand
- BiOptimizers Magnesium Breakthrough — 7 forms; very comprehensive; premium pricing
What to avoid
- Magnesium oxide (found in most supermarket brands) — nearly useless for systemic magnesium repletion
- Products that do not specify the form of magnesium used — assume it is oxide
- Excessively high single doses — above 400mg from supplements can cause loose stools and diarrhoea
Frequently Asked Questions
What is the best form of magnesium for sleep?
Magnesium glycinate (also called bisglycinate) is the most researched form for sleep quality improvement. It activates GABA receptors and its bound glycine reduces core body temperature — both key mechanisms for sleep onset.
How much magnesium should I take per day?
The UK recommended daily intake is 300mg for men and 270mg for women from all sources (food and supplements combined). From supplements specifically, 200–400mg of elemental magnesium per day is typical. Exceeding 400mg from supplements can cause digestive side effects.
Why is magnesium oxide sold so widely if it’s poorly absorbed?
It is cheap to produce and passes safety standards because it is technically not harmful. Marketing does not require specifying bioavailability. Most consumers do not know to look for the form, so manufacturers use the cheapest option.
Should I take magnesium in the morning or evening?
For sleep and relaxation benefits — evening, 30–60 minutes before bed. For energy and exercise performance (malate form) — morning or pre-exercise. A multi-form product can be taken in the evening to cover all three functions.
Related: Lily & Loaf Triple Magnesium Review | Is Magnesium Good for Weight Loss UK?
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