Magnesium Glycinate vs Citrate vs Oxide: Which Form and What Dose?

Short answer: glycinate (bisglycinate) is the best tolerated and easiest on the stomach. Citrate absorbs well but has a laxative effect at higher doses. Oxide is cheap, poorly absorbed, and mostly used to inflate the milligram figure on a label.

The number on the pack is probably not magnesium

This is the single most useful thing to understand. Magnesium is never sold on its own — it is bound to something else, and that compound weighs far more than the magnesium inside it.

A supplement advertising 1,500mg of magnesium bisglycinate contains roughly 150mg of actual magnesium. The rest is glycine. The magnesium that counts is called elemental magnesium, and a well-labelled product states it separately.

Rough elemental content by form:

• Magnesium oxide — about 60% elemental, but poorly absorbed
• Magnesium citrate — about 16% elemental
• Magnesium bisglycinate — about 10% elemental

Oxide looks impressive on a label precisely because it is mostly magnesium by weight. Very little of it reaches your bloodstream, which is why a high milligram figure alone tells you almost nothing.

The forms compared

• Bisglycinate (glycinate) — magnesium bound to glycine. Well absorbed and the gentlest on the digestive system. The usual choice for anyone who has had trouble with other forms.
• Citrate — well absorbed and inexpensive. Draws water into the bowel, which is why it is also sold as a laxative. Fine at moderate doses, less comfortable at high ones.
• Malate — bound to malic acid, well absorbed, commonly used in blends.
• Taurate — bound to taurine. Less studied than the others.
• Lactate and ascorbate — reasonably absorbed, usually appear as part of a multi-form blend.
• Oxide — poorly absorbed. Its main use is bulking out the headline number.

Blends combining several forms are common. The logic is that different compounds absorb through slightly different routes, so a mixed formula may be steadier than a single form. What matters either way is the elemental total and whether oxide is doing most of the heavy lifting.

How much magnesium per day?

The Nutrient Reference Value used on UK labels is 375mg of elemental magnesium per day, covering everything you get from food as well as supplements. Most adults get a substantial share from diet — green vegetables, nuts, seeds, wholegrains and dark chocolate are all good sources.

On supplements specifically, EFSA sets a tolerable upper intake of 250mg per day of magnesium added to food or taken as a supplement, on top of dietary intake. The UK Expert Group on Vitamins and Minerals has used a higher guidance figure of 400mg per day. The limiting factor at higher intakes is digestive tolerance rather than toxicity — loose stools are the usual first sign of taking more than suits you.

If you are new to magnesium, starting lower and increasing is more comfortable than starting high.

What magnesium is authorised to do

Under GB nutrition and health claim rules, magnesium may be described as contributing to:

• a reduction of tiredness and fatigue
• normal muscle function
• normal functioning of the nervous system
• normal psychological function
• normal protein synthesis
• the maintenance of normal bones and teeth
• electrolyte balance

These claims apply to a product supplying at least 15% of the NRV per serving. Claims beyond this list — about sleep, anxiety or stress in particular — are not authorised in Great Britain, whatever you may read elsewhere.

Capsules or gummies?

Absorption is governed by the form of magnesium, not the delivery format. Choose on practicality: capsules carry more per unit and suit higher doses; gummies are easier to take consistently and avoid swallowing tablets.

Our magnesium range

The Magnesium Glycinate 6-in-1 Advanced Complex uses six forms — bisglycinate, citrate, taurate, malate, L-ascorbate and lactate — with the elemental figure stated on the page, plus vitamin B6, vitamin D3 and zinc. 90 vegan capsules.

The Magnesium Glycinate 5-in-1 Gummies offer a multi-form blend with vitamin B6 in a sugar-free gummy, for anyone who would rather not take capsules.

Both sit in our sleep and calm range.