Matthew Messer

Matthew Messer


PCOS is a very common hormonal disorder that may affect more than 10% of women. It is important to address it as it can be joined by insulin resistance over time, which is a serious risk factor for several chronic diseases. Women with PCOS are very often deficient in vitamin D and supplementation with vitamin D3 can go a long way to improve the hormonal and metabolic problems associated with it.

Occurrence of vitamin D deficiency in PCOS

Polycystic ovary syndrome (PCOS) is one of the most common hormonal diseases in women of reproductive age worldwide. It is usually characterized by menstrual irregularities, androgen excess, and an overgrowth of cysts in the ovaries, which can be accompanied by unpleasant symptoms such as acne, increased body hair growth, and infertility.

Although the exact causes of PCOS are still unknown, it is thought that excessive androgen production, insulin resistance and inflammatory processes may play a role. In recent years, with the spread of PCOS, the search for effective therapies has become particularly important. Several studies have reported that, among other factors, vitamin D deficiency may play a role in the development of the disease, which is good news because the treatment of vitamin D deficiency is easy and has no side effects.

In a 2018 study, 639 women with PCOS and 449 fertile women were tested for vitamin D levels, divided into different categories based on their vitamin D levels. Women with PCOS were more likely to be vitamin D deficient, with 77% of them having a vitamin D level lower than 75 nmol/l, which is considered the cut-off for adequate levels. Healthy women had an average of 15.5 nmol/l higher vitamin D levels and 36% had adequate levels.

Lower levels of vitamin D were associated with poorer levels of the HOMA-IR index, a measure of insulin resistance, and of blood lipids. Apparently, vitamin D deficiency has quite a negative effect on PCOS, but how is this possible?

The link between vitamin D and PCOS

Vitamin D receptors are also found in insulin-producing beta cells, and once activated by vitamin D, insulin production is increased. Vitamin D deficiency also increases whole-body inflammation, which is known to play a role in the development of insulin resistance. Finally, it may also affect insulin production through its effects on calcium.

Patients with PCOS also frquently develop fat metabolism disorders, which increase the risk of cardiovascular disease. This is partly due to high levels of parathyroid hormone (PTH). Vitamin D lowers the levels of PTH, thereby supporting lipid metabolism and improving blood lipid levels.

Finally, vitamin D has a wide range of hormonal effects, which are important for the functioning of female hormones, among other things.

What is really important to know, of course, is whether and how much does vitamin D3 supplementation improve the symptoms of PCOS? A new meta-analysis provides answers to this question.

Benefits of vitamin D3 supplementation in PCOS

A meta-analysis published in 2023 summarized the results of 13 randomized trials that tested the effects of vitamin D3 supplementation in patients with PCOS.

The main factors that were tested for changes were different hormone levels, inflammation markers, (Hs-CRP) and cholesterol levels.

The results were as follows:

  • Levels of hs-CRP, a marker of inflammation and a major cardiovascular risk factor, were much lower in the vitamin D supplementation groups than in the control group.
  • Elevated testosterone levels, a problem in PCOS, were significantly reduced by vitamin D supplementation.
  • Although total cholesterol levels alone are not the best way to determine cardiovascular risk, they also decreased in the vitamin D supplementation groups.

The researchers conclude that vitamin D supplementation may help to alleviate the negative hormonal and metabolic changes associated with PCOS. If you know someone with PCOS who may not be supplementing with vitamin D, you may want to send them this article!

  1. Krul-Poel YHM, Koenders PP, Steegers-Theunissen RP, Ten Boekel E, Wee MMT, Louwers Y, Lips P, Laven JSE, Simsek S. Vitamin D and metabolic disturbances in polycystic ovary syndrome (PCOS): A cross-sectional study. PLoS One. 2018 Dec 4;13(12):e0204748. doi: 10.1371/journal.pone.0204748. PMID: 30513089; PMCID: PMC6279035.
  2. Zhang B, Yao X, Zhong X, Hu Y, Xu J. Vitamin D supplementation in the treatment of polycystic ovary syndrome: A meta-analysis of randomized controlled trials. Heliyon. 2023 Mar 8;9(3):e14291. doi: 10.1016/j.heliyon.2023.e14291. PMID: 36942243; PMCID: PMC10023924.

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