Compare every Magnesium Oxide product across UK retailers on Suppio, ranked by true value - price per active dose, not pack size. Prices refreshed daily.
Low-cost magnesium salt with modest absorption
We rank Magnesium Oxide by price per gram of active ingredient - not by pack size - so a bigger tub with a worse price per dose can't outrank a smaller one that's actually cheaper.
Magnesium Oxide is a magnesium salt, which is a compound created by combining magnesium with oxygen. It is known for having modest absorption, meaning the body does not take up the mineral as easily as it does with other types of magnesium.
It is used as a supplement to increase the levels of magnesium in the body. Because it contains a high concentration of the mineral per gram, it is often used when a high dose is required in a small pill.
To make this supplement, manufacturers react magnesium metal or magnesium hydroxide with oxygen or heat. This process creates a stable powder that can then be pressed into tablets or filled into capsules for sale.
This ingredient is positioned in the mid-range for price. While the raw materials are relatively inexpensive to source, the final cost reflects the standard manufacturing and packaging processes used for common mineral salts.
| Purpose | Typical studied dose | Evidence |
|---|---|---|
| type 2 diabetes control | 500 mg to 1,000 mg magnesium oxide (providing 300 to 600 mg elemental magnesium) daily | limited |
| chronic constipation | Not specified | established |
| insomnia | 250 mg to 729 mg daily | emerging |
| anxiety | Not specified | emerging |
| bone mineral density and bone turnover | 250 mg to 1,800 mg | emerging |
| Form | What it is | Why chosen | Does it actually differ? |
|---|---|---|---|
| Magnesium Oxide | A form of magnesium that is very poorly absorbed by the body. | It can be used to increase stool frequency and soften stools, or to improve certain metabolic parameters in women with polycystic ovary syndrome. | It has extremely poor absorption (as low as 4 percent in humans) and a higher risk of stomach-related side effects compared to other forms. |
| Magnesium Citrate | A widely studied form of magnesium. | It is chosen for its consistently good bioavailability, meaning the body absorbs it well. | It is specifically noted as having good absorption, unlike magnesium oxide which is not recommended for increasing magnesium levels. |
| Magnesium Glycinate | A salt form of magnesium. | It is used because it appears to have good bioavailability. | It is listed as having good absorption, making it superior to magnesium oxide for raising magnesium levels in the body. |
Verdict: It is worth seeking out forms like Magnesium Citrate or Glycinate over Magnesium Oxide because they are much better absorbed by the body and have fewer stomach side effects.
Suppio matches identical products across UK retailers by barcode, then ranks by price per active dose rather than sticker price. Value rankings only ever include listings Suppio has independently verified against the live retailer page - unverified data is shown on each product’s own page but excluded from ranking.
Prices across our retailer network are refreshed at least daily.
Low-cost magnesium salt with modest absorption
We rank Magnesium Oxide by price per gram of active ingredient - not by pack size - so a bigger tub with a worse price per dose can't outrank a smaller one that's actually cheaper.
Suppio matches identical products across UK retailers by barcode, then ranks by price per active dose rather than sticker price. Value rankings only ever include listings Suppio has independently verified against the live retailer page - unverified data is shown on each product’s own page but excluded from ranking.
Prices across our retailer network are refreshed at least daily.