Early on in my quest to manage my case of PCOS holistically, I suspected that I had a progesterone deficiency. In Googling possible remedies, magnesium supplementation kept appearing, and so I added it in (along with zinc, a topic for another post). Recently, I’ve been doing more digging into the actual science behind the use of magnesium for PCOS management, and surprisingly, I cannot find any studies that show a causal link between magnesium supplementation and progesterone levels in humans, although there are other studies that show magnesium levels in the body change as hormone levels change across the menstrual cycle (the reverse direction of causation). But adding in magnesium and zinc seemed to help my symptoms, so let’s see how that might be.

Magnesium supplementation and PCOS

I started my research by trying to find randomized control trials of magnesium supplementation among women with PCOS. As seems to be a theme when I start investigating a topic, the literature is sparse and disappointing.

There are some studies that test for magnesium levels in women’s blood and compare levels across women with and without PCOS. A meta-analysis of these studies demonstrates that in 60% of those studies, average magnesium levels were lower in the women with PCOS (Babapour et al. 2021). In the remainder of studies, no statistically significant difference was found between the two groups of women. This kind of correlation study, however, cannot differentiate between low magnesium causing PCOS among some women or PCOS causing low magnesium among some women with PCOS.

Another study considered the impact of magnesium consumption (as well as fiber) in the diet through the use of a 3-day food journal, completed by 87 women with PCOS and 50 women without PCOS (Cutler et al. 2019). They paired the food journal data with various markers of well-being taken through blood samples. They found that women with PCOS consumed about 21% fewer grams of fiber and about 13% fewer milligrams of magnesium than those without PCOS. Increased consumption of magnesium was associated with decreased insulin resistance, decreased testosterone, and decreased C-reactive protein which is a measure of systemic inflammation. We’ll have a full discussion of fiber in a later post, but I’d also like to highlight that they found increased fiber intake was associated with lower insulin resistance, lower fasting insulin, lower testosterone, lower DHEA-s (another androgen), lower triglycerides, and lower LDL cholesterol. While this study cannot conclusively determine causation, it seems unlikely that PCOS leads women to eat less fiber and/or consume less magnesium, so there may be some amount of causality in their findings. However, we cannot rule out the possibility that women who consume more magnesium and/or fiber are also more likely to do other things that are actually improving their biomarkers instead of the magnesium and fiber.

There are three studies that make use of a randomized control trial of magnesium supplementation, a method that would allow us to determine causation. One of these studies has had its publications retracted due to omission of critical information about study design that would impact interpretation of results. Due to the uncertainty around the validity of their results, that study will not be addressed here. That leaves two studies using randomized control trials, the gold standard for determining the effect of magnesium supplementation on women with PCOS.

One of these studies recruited 60 women with PCOS. Half were given a daily supplement of 250 mg of magnesium and 400 mg of vitamin E per day (Shokrpour and Asemi 2019). The other half received a placebo. Fasting blood samples were taken at the start of the study and after 12 weeks of administration of the supplement/placebo. They found that within the group of women receiving the supplement, sex-hormone binding globulin increased (a positive change because it helps to neutralize excess androgens), an index of free androgens decreased, C-reactive protein decreased, hirsutism decreased, nitric oxide increased (which helps with blood pressure regulation), and total antioxidant capacity increased. Among the control group, the only statistically significant change that occurred across the 12 weeks was an increase in C-reactive protein. Relative to the changes in the control group, all trends in the treatment group are statistically significantly different than the trends found in the control group, except for the change in sex hormone binding globulin. This means that we can be pretty certain the trends found in the treatment group are not just trends that we would expect to observe over time in a group of women with PCOS. Unfortunately, this study did not consider the impact of magnesium on insulin resistance, nor can we separate out the effects of magnesium from the effects of the vitamin E in the supplement.

A second randomized control trial considered only magnesium supplementation, with the treatment group receiving 250 mg of magnesium oxide daily for 8 weeks, while the control group received a placebo (Farsinejad-Marj et al. 2020). Like the previous study, they recruited 60 women with PCOS in total and took blood samples before and after the intervention. They found a decrease in BMI among the treatment group, and unlike the control group, the treatment group did not experience an increase in waist circumference over the intervention period. This study found no impact of supplementation on fasting glucose levels or measures of insulin resistance. Unlike the previous study, they found no impact on sex hormone binding globulin, free androgen index, or other measured sex hormones. This study did not consider C-reactive protein, nitric oxide, or hirsutism. It should be noted that this intervention lasted only 8 weeks while the previous one lasted 12 weeks. As we will see below, some of the impacts of magnesium may require longer term use to be detected. The dosage here is also only about 158 mg of magnesium itself because this dosage is based on magnesium oxide. As we’ll see below, most studies that consider the impact of magnesium supplementation on the population at large use at least 300 mg of magnesium.

Magnesium supplementation and insulin resistance

While there are limited studies on the effects of magnesium supplementation on women with PCOS, there is a decent amount of literature on magnesium supplementation on insulin resistance in the general population. Given the high prevalence of insulin resistance among women with PCOS, this literature is relevant here.

Two studies provide convenient reviews of this literature. The first reviewed 21 studies that considered the effect of magnesium supplementation on insulin resistance (Simental-Mendia et al. 2016). Across studies, they find that there is a significant impact of magnesium supplementation on HOMA-IR, a measure of insulin resistance that considers both fasting blood glucose and fasting insulin levels. They find that those studies that considered interventions of at least 4 months were more likely to observe a significant reduction in insulin resistance and plasma glucose levels. Studies that considered populations who were deficient in magnesium to start were also more likely to observe a significant impact of magnesium supplementation on insulin resistance. Interestingly, across studies, there is no difference in impact as the dosage of magnesium changes, although all studies used at least 300 mg per day.

A second study analyzed 12 studies of magnesium supplementation on insulin resistance (Silva Morais et al. 2017). They excluded studies that restricted their sample populations based on sex, race, or ethnicity, resulting in a smaller number of studies considered. Of the 12 studies considered, three studies found no impact of supplementation. These included a 12-week study of healthy participants with no insulin resistance, a 12-week study of type 2 diabetics that used magnesium lactate (a form not often studied), and a 12-week study considering people who had kidney transplants 2 weeks prior to the start of the study (a rather unique subset of the general population). The remainder of the studies ranged from 6 to 24 weeks, and included populations of healthy individuals with no insulin resistance, healthy individuals with insulin resistance and/or prediabetes, and individuals with type 2 diabetes or gestational diabetes. Magnesium oxide and magnesium chloride were the most commonly used forms of magnesium supplementation, and the dosage for all but one study (the one considering those with gestational diabetes) used dosages of at least 300 mg/day. Across these broad participant ranges, at least one measure of insulin resistance improved across the intervention period.

Magnesium supplementation and premenstrual syndrome

Lastly, there is evidence that magnesium supplementation may ease premenstrual syndrome (PMS) symptoms which I think is worth discussing here as well, although PMS is not a phenomenon that is specific to PCOS. Several studies have considered the use of 250 mg magnesium in combination with 40 mg of vitamin B6 daily throughout the entire menstrual cycle (Porri et al. 2021). After about 2 months of supplementation, treatment groups experienced statistically significant reductions in symptom severity relative to the control groups who received placebo supplements.

Food sources of magnesium

While most studies consider magnesium supplementation, you can increase consumption of magnesium by consuming more foods rich in magnesium. The list below includes some of the best sources of magnesium with the amount of magnesium per serving found in the food (NIH 2022):

1. Pumpkin seeds, 1 oz (156 mg)

2. Chia seeds, 1 oz (111 mg)

3. Almonds, dry roasted 1 oz (80 mg)

4. Spinach, boiled, 1/2 cup (78 mg)

5. Cashews, dry roasted, 1 oz (74 mg)

6. Peanuts, oil roasted, 1/4 cup (63 mg)

7. Black beans, cooked, 1/2 cup (60 mg)

8. Edamame, shelled and cooked, 1/2 cup (50 mg)

9. Potato, baked with skin, 3.5 ounces (43 mg)

10. Kidney beans, canned, 1/2 cup (35 mg)

11. Banana, 1 medium (32 mg)

It should be noted that most sources of magnesium (whole grains, seeds, legumes, and some nuts) contain phytates which impair our ability to absorb the minerals they contain, like magnesium. Beans should always be soaked before consuming and consuming sprouted versions where possible also increases absorption. This absorption issue is part of the reason why supplementation may be helpful for some women (and men!).

Need for future research

As we see time and time again, there is a need for further research on the use of magnesium supplements for PCOS management. Given the underlying genetic mutations that contribute to the majority of PCOS cases, it would be helpful to have studies that specifically look at the use of magnesium supplements for women with PCOS, as they may or may not experience the same results as the general population. These studies should consider magnesium supplements alone (instead of in combination with vitamin E) and should consider the impacts of supplementation that occurs for at least 4 months given the longer term use required to see impacts in the general population.

Take home points

Magnesium may benefit women with PCOS through its impact on insulin resistance. Supplementation of magnesium in conjunction with vitamin E may improve androgen levels and hirsutism. Supplementation of magnesium with vitamin B6 may improve PMS symptoms. Most studies with only female participants used 250 mg while those not focused on females alone used at least 300 mg per day. Always talk to a trusted healthcare professional before starting a supplement regimen.

References

Babapour M, Mohammadi H, Kazemi M, Hadi A, Rezazadegan M, and Askari G. 2021. Associations Between Serum Magnesium Concentrations and Polycystic Ovary Syndrome Status: a Systematic Review and Meta-analysis. Biological Trace Element Research 199:1297–1305 https://doi.org/10.1007/s12011-020-02275-9

Cutler DA, Pride SM, and Cheung AP. 2019. Low Intakes of Dietary Fiber and Magnesium are Associated with Insulin Resistance and Hyperandrogenism in Polycystic Ovary Syndrome: A Cohort Study. Food Science Nutrition 7:1426–1437. https://doi.org/10.1002/fsn3.977

Farsinejad-Marj M, Azadbakht L, Mardanian F, Saneei P, and Esmaillzadeh A. 2020. Clinical and Metabolic Responses to Magnesium Supplementation in Women with Polycystic Ovary Syndrome. Biological Trace Element Research 196:349–358. https://doi.org/10.1007/s12011-019-01923-z

National Institutes of Health [NIH]. 2022. Magnesium: Fact Sheet for Health Professionals. Available: https://ods.od.nih.gov/factsheets/Magnesium-HealthProfessional/

Porri D, Biesalski HK, Limitone A, Bertuzzo L, and Cena H. 2021. Effect of Magnesium Supplementation on Women’s Health and Well-being. NFS Journal 23:30–36. https://doi.org/10.1016/j.nfs.2021.03.003

Shokrpour M and Asemi Z. 2019. The Effects of Magnesium and Vitamin E Co-Supplementation on Hormonal Status and Biomarkers of Inflammation and Oxidative Stress in Women with Polycystic Ovary Syndrome. Biological Trace Element Research 191:54–60. https://doi.org/10.1007/s12011-018-1602-9

Silva Morais JB, Soares Severo J, Reis de Alencar GR, Soares de Oliveira AR, Climaco Cruz KJ,
do Nascimento Marreiro D, de Almendra Freitas BJS, Resende de Carvalho CM, de Carvalho e Martins MC, and Goncalves Frota KM. 2017. Effect of Magnesium Supplementation on Insulin Resistance in Humans: A Systematic Review. Nutrition 38:54–60. http://dx.doi.org/10.1016/j.nut.2017.01.009

Simental-Mendíaa LE, Sahebkarb A, Rodríguez-Morána M, and Guerrero-Romeroa F. 2016. A Systematic Review and Meta-analysis of Randomized Controlled Trials on the Effects of Magnesium Supplementation on Insulin Sensitivity and Glucose Control. Pharmacological Research 111:272–282. http://dx.doi.org/10.1016/j.phrs.2016.06.019

Disclaimer: This post is not intended to diagnose or treat any medical issues. It is intended for informational purposes only. I am not a medical practitioner. Always consult a trusted healthcare provider with any questions you may have about a medical condition or treatment and before starting any new health care regimen.