Magnesium and PCOS
Magnesium is one of the most underappreciated nutrients in PCOS management. Women with PCOS are significantly more likely to have low serum magnesium than women without the condition – and this matters, because magnesium plays a direct, mechanistic role in insulin signalling, glucose metabolism, and the hormonal dysregulation that drives PCOS symptoms.
In my clinical practice, measuring magnesium (and often finding it low or at the very bottom of the reference range) is a routine part of working with new PCOS patients. Correcting magnesium deficiency is not a dramatic intervention, but it is a foundational one – and the research supports it.
Why Magnesium and PCOS Matter
Magnesium is involved in over 300 enzymatic reactions in the body. In the context of PCOS, its most important roles are:
- Acting as a second messenger for insulin signalling, magnesium is required for the auto-phosphorylation of the insulin receptor, a critical step in insulin’s ability to stimulate glucose uptake
- Facilitating glucose transport into cells via GLUT-4 transporter translocation
- Regulating the AMPK pathway, which governs cellular energy metabolism and insulin sensitivity
- Supporting adrenal stress response regulation, which is relevant for the adrenal PCOS subtype
The association between low magnesium levels and PCOS is well documented. A cross-sectional study found that women with PCOS had a 19-fold greater risk of magnesium deficiency than women without PCOS. A 2021 systematic review and meta-analysis confirmed that serum magnesium concentrations are lower in overweight and obese women with PCOS compared to controls.
The 2025 systematic review and meta-analysis published in Medicina, specifically examining RCTs on magnesium and PCOS supplementation, found improvements in blood sugar parameters, lipid profiles, blood pressure, and, importantly, androgen markers, including testosterone and DHEA.
Does Magnesium Supplementation Actually Help PCOS?
The evidence is nuanced, and I want to be direct with you about what the research shows:
Magnesium and PCOS alone: Evidence for magnesium supplementation in isolation for PCOS outcomes is mixed. A 2022 systematic review found that magnesium supplementation alone did not produce statistically significant improvements in oxidative stress, blood glucose, or serum lipids in PCOS patients.
Magnesium and PCOS in combination: The picture improves substantially when magnesium is combined with other nutrients. Magnesium combined with vitamin E, or with zinc, calcium, and vitamin D, significantly improved glucose metabolism, insulin resistance (HOMA-IR), triglycerides, total cholesterol, and inflammatory markers in PCOS patients.
2024 RCT: A clinical trial published in Biological Trace Element Research tested 250mg/day of magnesium oxide in women with PCOS for two months. Improvements were observed in anthropometric and metabolic parameters, supporting the value of supplementation.
The weight of the evidence suggests that magnesium is most effective as part of a broader nutritional approach rather than as a single-nutrient intervention, which is consistent with the general principle that PCOS is a multifactorial condition requiring comprehensive management.
Magnesium and PCOS: Which Type of Magnesium Is Best?
This is where supplement selection gets important. Not all forms of magnesium are equally absorbed or equally appropriate for PCOS. Here is a clinical breakdown:
Magnesium glycinate
This is generally my first recommendation for women with PCOS. Magnesium glycinate (magnesium bound to the amino acid glycine) has excellent bioavailability, is well-tolerated by the gut, and has the added benefit that glycine itself has mild anti-anxiety and sleep-supportive properties. For women with PCOS who also struggle with anxiety or poor sleep, which is common, this form addresses multiple issues simultaneously.
Magnesium bisglycinate
Similar to glycinate with high absorption and gentle gastrointestinal profile. Often used interchangeably with glycinate in clinical practice.
Magnesium threonate
This form has superior central nervous system penetration and is the form of choice for cognitive function and anxiety. For women with PCOS-related anxiety or mood dysregulation, this is worth considering, though it is typically more expensive.
Magnesium oxide
This is the cheapest and most widely available form, and the one used in the 2024 PCOS RCT described above. However, it has poor bioavailability (only about 4% is absorbed) and commonly causes loose stools at higher doses. It is the least preferred option despite being the most studied in PCOS trials, partly because it is cheap and easy to standardize in research.
Magnesium citrate
Reasonably good bioavailability, commonly available, but has a laxative effect at higher doses. Appropriate for women who also have constipation (common in PCOS), but not ideal as a primary magnesium source.
Magnesium and PCOS: How Much Should You Take?
The RCTs in PCOS have generally used 250–300mg of elemental magnesium per day. The Canadian RDA for magnesium in women is 310–320mg per day, meaning many women are not meeting basic dietary requirements, let alone the higher levels that may be therapeutic in the context of PCOS-related deficiency.
Dietary sources of magnesium worth emphasizing: dark leafy greens, pumpkin seeds, almonds, dark chocolate, black beans, and avocado. Prioritizing these foods alongside supplementation is ideal.
Starting dose: 150–200mg elemental magnesium glycinate daily, taken with food, building to 300mg if tolerated. Taking it in the evening supports both sleep and absorption.
As with all supplements, discuss magnesium with your healthcare provider before starting, particularly if you have kidney disease or take medications that affect magnesium levels (such as certain diuretics or proton pump inhibitors). Any mineral supplements, like magnesium, should be spaced well away from other medications as it may affect their absorption, particularly thyroid medication.
The Bottom Line on Magnesium and PCOS
Magnesium is not a dramatic intervention, but it is an important foundational one for women with PCOS, particularly those with insulin resistance, anxiety, sleep disruption, and cardiometabolic risk factors. Low magnesium worsens insulin resistance – and correcting deficiency removes an obstacle to the improvements you are working toward with your other PCOS management strategies.
Choose magnesium glycinate or bisglycinate for best absorption and tolerability. Take it in the evening. And eat your pumpkin seeds.
References for Magnesium and PCOS:
Shahmoradi S et al. (2024). Effect of magnesium supplementation on insulin resistance in PCOS. Biol Trace Elem Res 202(3):941-946. PMID: 37393389
Li R et al. (2022). Magnesium alone or in combination with other supplements in PCOS: Systematic review. Front Endocrinol 13:974042. PMID: 35992132
Babapour M et al. (2021). Serum magnesium concentrations and PCOS status: Systematic review and meta-analysis. Biol Trace Elem Res 199(4):1297-1305. PMID: 32812171
Cirar Daziroglu ME et al. (2025). Magnesium supplementation in PCOS: Systematic review and meta-analysis of RCTs. Medicina 61(2):280. PMID: 40005397
