Comparison
Zinc vs. Magnesium
Zinc or magnesium – what is proven for colds, sleep and cramps?
The short answer
Both are essential minerals, both are involved in more than 300 enzymes, and both score 7 out of 10 for human evidence in the BK-Score. There is no direct comparison; the studies address different questions and can only be laid side by side. Zinc: in a meta-analysis of 5,446 adults there were 5 fewer respiratory infections per 100 person-months, with moderate certainty of evidence. However, the 2024 Cochrane review missed its primary endpoint for prevention, and the shortening by 2.37 days is not a robust figure given 97 percent heterogeneity. Magnesium: a double-blind trial with 155 participants showed a small effect on sleep, measured by questionnaire only. For nocturnal leg cramps, two controlled analyses missed their primary endpoint.
The numbers side by side
| Axis | Zinc | Magnesium | Difference |
|---|---|---|---|
| Human evidenceHow much and how good the data in humans are | 7 | 7 | even |
| MechanismHow well the chain of action is understood | 8 | 8 | even |
| Safety dataHow well safety has been studied – not how safe it is | 8 | 9 | Magnesium better studied |
| Hype gap10 means: the advertising stays level with the data | 6 | 6 | even |
| Track record of useHow much documented use in humans exists – does not measure whether it works | 10 | 10 | even |
| Rating | Supported, with caveats · Supported, with caveats | ||
“Track record of use” measures how long and how widely something has been used in humans – not whether it works. The BK-Score is a subjective assessment by Biohacking Kompakt based on published scoring rules (German). It is not a scientific rating, not the consensus of a professional society and not a medical recommendation.
Why these numbers
Zinc
For deficiency and for cold duration there are controlled trials and meta-analyses, and the role in immune function is mechanistically clear. Overdosing disrupts copper balance – something rarely mentioned in advertising.
Magnesium
Very well established biochemically as a cofactor of hundreds of enzymes, with solid studies on blood pressure and sleep quality, but few large outcome trials. Safety is well studied; the marketing of individual salt forms goes beyond the comparative data.
Frequently asked questions
Is zinc or magnesium better for colds?
Only zinc has evidence here, and even that comes with caveats. Hunter 2021 reports 5 fewer respiratory infections per 100 person-months across 28 trials, a number needed to treat of 20. The 2024 Cochrane review with 34 trials, by contrast, missed its primary endpoint of cold risk (RR 0.93). For cold duration, both analyses show a shortening, but only the direction is robust. The sources reviewed contain no studies on magnesium and colds.
Does magnesium or zinc help with sleep?
For magnesium there is a significant but small finding: in Schuster 2025, a double-blind trial with 155 participants, the Insomnia Severity Index fell by 3.9 points versus 2.3 on placebo, p = 0.049, effect size d = 0.2. It was measured by questionnaire only. A review of 12 trials rates the evidence as low to very low. The sources reviewed contain no studies on zinc and sleep.
Does magnesium help with leg cramps?
Not according to the data reviewed. A Cochrane review with 11 trials and 735 participants missed its primary endpoint for nocturnal leg cramps. Kuusipalo 2026 confirmed this with 121 enrolled participants: a difference of −0.20 cramps per week, p = 0.929. In the same trial, compression stockings reduced frequency by 1.43 per week. For exercise-associated cramps, the Cochrane review found not a single randomized trial, so any robust study is missing.
What are the side effects of zinc and magnesium?
With zinc, non-serious side effects were more frequent in both large analyses, with RR 1.34 and 1.41 and a number needed to harm of 7; users mainly report nausea. Persistently high intake can cause copper deficiency. With magnesium, diarrhoea is the most common side effect, in the Cochrane review in up to 37 percent versus 14 percent on placebo; caution is advised with severe kidney failure. This information does not replace medical advice.
See all ratings in the ranking (German app)
Information only, not medical advice and not a usage or dosage recommendation. Prescription-only and unapproved substances belong in a doctor's hands.