Ingredient
Magnesium
Research dose
300–350 mg/day
Evidence: Moderate Trials gave magnesium daily, for weeks: what counts is the amount you take in a day.
Magnesium from a supplement: 300 mg a day was enough to raise blood magnesium across 34 trials, whose median dose was 368 mg a day. The US upper limit for magnesium from supplements is 350 mg a day; above it diarrhoea and nausea are more likely. The RDA, 400–420 mg for men and 310–320 mg for women, counts food too.
Upper reference: 350 mg per serving. One serving at or above it is marked “too much”.
Sources
Zhang X, Li Y, Del Gobbo LC, et al. Effects of magnesium supplementation on blood pressure: a meta-analysis of randomized double-blind placebo-controlled trials. Hypertension. 2016;68(2):324-333.
Supports the research dose. Where: Abstract: "Mg supplementation at a median dose of 368 mg/d for a median duration of 3 months"; "Mg supplementation with a dose of 300 mg/d or duration of 1 month is sufficient to elevate serum Mg and reduce BP". Read the source, checked 9 Oct 2026.
Matek Sarić M, Sorić T, Juko Kasap Ž, et al. Magnesium: health effects, deficiency burden, and future public health directions. Nutrients. 2025;17(22):3626.
Supports the upper reference. Where: Section 6.2: "The Tolerable Upper Intake Level (UL) for supplemental magnesium is 350 mg/day (excluding food sources) in adults"; section 4.2: RDA "400–420 mg/day for adult men and 310–320 mg/day for adult women". Read the source, checked 9 Oct 2026.
Magnesium supplements we've checked
21 magnesium supplements, each judged on how much a day its label's own directions give. See them all, ranked.
In the pre-workouts we've checked
| Product | Per scoop | Verdict |
|---|---|---|
| RAW Nutrition Essential Performance | 50 mg | Not graded |
| Jocko Fuel Pre-Workout | 15 mg | Not graded |
| BSN N.O.-Xplode | 125 mg | Not graded |