Magnesium & Testosterone


Magnesium is a key mineral for boosting testosterone. When paired with potassium and zinc, it constitutes the most noticeable testosterone boosting effect that I have yet witnessed in my own body. When supplementing with magnesium, potassium and zinc magnesium my voice noticeably deepens and sexual function improves. My personal dose is around 1.5g of elemental potassium per day (in split doses), combined with around 400mg of magnesium.

This article focuses on studies related to magnesium in isolation.

It is important to note that dietary factors such as consumption of oxalic acid (oxalate) or phytic acid (phytate) can significantly reduce magnesium absorption.

Animal Studies

Animal study - The more magnesium, the more testosterone in rats
Type of study: RCT, animal study (rats)
Supplement: Magnesium Sulfate MgSO4
Duration: 26 weeks (6 months)
Groups: 4 groups, control, 0.5g per 100g of MgSO4, 1g per 100g and 1.5g per 100g
Found: The rats were studied for 26 weeks, with hormonal and other measures taken at both 13 weeks and 26 weeks. Both Lutenizing Hormone, and Testosterone increased in a roughly linear relationship with magnesium intake, but FSH remained stable. Prostate weights of the rats also increased with magnesium intake. The rise in LH suggests magnesium has a beneficial impact on the testosterone feedback system.
Note: Dihydrotestosterone (DHT) and Estrogen (E) were not measured.

Human Observational Studies

Serum magnesium correlates with testosterone in elderly men
Type of study: Observational, cross-sectional
Participants: Elderly men
Sample size: 399
Age: 65+
Finding: Higher serum magnesium is strongly correlated with higher total testosterone after controlling for a range of factors. Given that this was an observational study, it cannot be used to establish causation. Magnesium was also associated with higher IGF-1.
(Estrogen, LH, Free Testosterone and DHT were not measured)

Magnesium inversely associated with body fat in elderly

The serum magnesium concentration is an independent correlate of muscle performance in older persons
"Plasma magnesium was significantly correlated (r = 0.46; p less than 0.002) with maximal oxygen consumption, ml/(kg x min), among the athletes."

Human Experimental Studies

Experimental trial - Magnesium boosts testosterone in sedentary and athletic men
Type of study: Experimental trial (not quite RCT)
Participants: Young men
Duration: 4 weeks
Sample size: 30
Dosage: 10 mg magnesium per kilogram body weight (equivalent of 840mg for the average UK male)
Age: 18-22
The study looked at three groups of participants: 10 sedentary men who received supplementation, 10 taekwondo practitioners who received supplements and 10 taekwondo practitioners who didn't.

It's wrong to automatically conclude that if you start exercising and taking magnesium you'll get similar results. Although it is possible, this study does not prove that. Remember: people were not randomized to exercise, it looked at people who already were exercising.

The Original ZMA trial, funded by the developers, that show it works

Small Human RCT - Magnesium supplementation enhances muscle building
Supplement: Magnesium Oxide
Duration: 7 weeks.
Study looked at effect of strength training on young untrained males. It involved 26 participants, 14 in the control group, 12 in the group supplemented with magnesium. Participants were between 18-30 years old. Taking existing dietary into account, participants in the experimental group were given magnesium oxide to bring intake up to 8 mg/kg body weight/day e.g. 560mg for a 70kg man. Torque strength was around 20% higher in the experimental group. I've not looked beyond the abstract yet, but presumably they took into account torque strength at baseline!

Small Human RCT - ZMA yielding 450mg per day of magnesium, does nothing for testosterone
Participants: 14, young men.
In a major challenge to the theory that magnesium raises testosterone, supplementation with ZMA yielding 450mg of magnesium did nothing to raise testosterone. A few possible explanations:
- Magnesium does nothing.
- Magnesium exerts effects by boosting sleep, but sleep was already good in these individuals.
- Magnesium exerts effects by improving mood, but mood was already good in these individuals.
- Magnesium only raises testosterone if there is a deficiency.
- Magnesium requires other dietary factors (like potassium) to work.
Based on personal experience, I'd lean towards the latter two explanations.

Another ZMA failure

In Vitro Studies

In Vitro study - Magnesium decreases the binding of testosterone to sex hormone binding globulin SHGB
- Relevance of this is unclear. I'll need to look at dosage in more detail.


No relationship between magnesium and 5AR activity in prostates

Magnesium absorption

When taking magnesium in supplemental form, or eating magnesium rich foods, it is vital to consider your consumption of phytate and oxalate. Spinach for example, is extremely rich in oxalate - so despite being high in magnesium, it is possible relatively little of that magnesium is absorbed. Almonds, another food rich in magnesium, are also high in both phytate and oxalate. Potentially, soaking the almonds (and other nuts) can greatly reduce phytate and oxalate levels, rendering the magnesium more bio-available.

2017 REVIEW:

Phytic acid (Phytate) significantly reduces magnesium absorption

Oxalic acid (Oxalate) significantly reduces magnesium absorption.

Magnesium absorption

To reiview




Magnesium and the HPA axis

supraphysiologic concentrations of magnesium don't have any major effect on hormones.