Polycystic ovary syndromePatient friendly summary

  • Solar ultraviolet-B light can raise vitamin D levels.
  • Higher vitamin D levels may reduce PCOS symptoms.

Polycystic ovary syndrome (PCOS) is one of the most common female hormone disorders. PCOS affects about 5% to 10% of women of reproductive age (12–45 years old). PCOS is one of the leading causes of low female fertility.

PCOS is characterized by obesity, lack of ovulation, irregular or absent menstruation, acne, and large amounts of masculine hormones. Severity of symptoms varies greatly.

Risk factors for PCOS

The cause of PCOS is unknown. Contributing factors include:

  • Insulin resistance
  • Diabetes
  • Obesity

Sunlight exposure and PCOS risk

There are no reported studies of sunlight and PCOS risk.

Vitamin D and PCOS

Vitamin D levels

Women with PCOS and high body mass index usually have lower vitamin D levels. Studies in Germany, Austria, and Turkey linked low vitamin D levels to obesity and insulin resistance but not to PCOS per se.

Obesity and insulin resistance are two characteristics of the metabolic syndrome. This syndrome is often seen with PCOS. It also causes a predisposition to cardiovascular disease. Signs include fat around abdomen, high triglycerides, low high density lipoprotein-cholesterol (HDL-C) or good cholesterol, high low density lipoprotein-cholesterol (LDL-C) or bad cholesterol, insulin resistance, increased blood sugar, and increased inflammation.

How vitamin D works

Vitamin D offers many health benefits for women with PCOS:

  • Increases insulin sensitivity
  • Reduces risk of high blood pressure

These benefits also lower risk of the metabolic syndrome.


There is no evidence that vitamin D affects PCOS. However, vitamin D may reduce the risk and features of the metabolic syndrome.

Vitamin D and calcium

A study in New York increased vitamin D and calcium supplements. Within two months, menstrual cycles normalized and abnormal bleeding stopped.


A study in Turkey found that a single large dose of vitamin D3 (cholecalciferol) helped insulin resistance.

Based on studies of many diseases, the ideal vitamin D level is above 30–40 ng/mL (75–100 nmol/L). To achieve these levels, 1000–5000 (IU) (25-125 mcg)/day of vitamin D3 is recommended. However, there is considerable person-to-person variability. Vitamin D blood levels should be tested before and after vitamin D3 supplements.

Raising vitamin D levels has important benefits for women with PCOS. Vitamin D aids the reproductive system. It also stabilizes the metabolic syndrome. This syndrome is frequently seen with PCOS.

Find out more...

We will be adding a detailed evidence summary on this topic in the near future.  Please check back soon to find out more.

Page last edited: 17 May 2011