Is there a link between vitamin D and PCOS? The “sunshine” vitamin is known to improve mood and help with calcium and phosphate regulation. But what about its impact on PCOS? We dive into vitamin D and its effect on PCOS in this article. Keep reading!
What is PCOS?
Polycystic ovary syndrome, or PCOS, is a common condition affecting how an individual’s ovaries work. There are many symptoms of PCOS, which will vary from person to person. As PCOS cannot be cured, many people turn to lifestyle interventions to manage their symptoms. This may include nutrition tweaks or adding in supplements like vitamin D.
What is Vitamin D?
Vitamin D is a fat-soluble hormone, that the body creates from direct sunlight on the skin when outdoors. In the summer months, most individuals will get enough vitamin D through sunlight, however, throughout the winter months, this isn’t the case.
Vitamin D helps to regulate the amount of calcium and phosphate in the body. These nutrients are essential in keeping bones, teeth and muscles healthy.
Vitamin D and PCOS: what’s the link
You may be wondering what the link between vitamin D and PCOS is. Interestingly, some recent studies have found that vitamin D deficiency is common in individuals with PCOS and the prevalence of deficiency is higher in people with PCOS than the general population. It has been estimated that 67% to 85% of people with PCOS are deficient in vitamin D. Whereas, in the US, it is estimated that about 35% of people have a vitamin D deficiency.
Benefits of vitamin D for PCOS
So, does supplementing with vitamin D have benefits for PCOS? Let’s take a look at the evidence.
Improves insulin resistance
Many people with PCOS have insulin resistance. In fact, up to 80% of people with PCOS have insulin resistance, regardless of their body size or shape. A meta-analysis evaluated the effect of vitamin D supplementation on people with PCOS. Their results indicated that vitamin D significantly improved HOMA-IR, a model that measures insulin resistance.
A 2018 study of 36 participants found that, compared to the placebo group, vitamin D supplementation significantly decreased fasting plasma glucose and HOMA-B levels, indicating improved insulin resistance.
May improve fertility
Another benefit of vitamin D supplementation is the impact it can have on menstrual cycle regulation, potentially also improving fertility. One 3-month study concluded that supplementing 400IU of vitamin D, 1,000mg of calcium a day and metformin can help in maintaining a regular menstrual cycle.
Observational studies have seen that vitamin D may increase endometrial thickness in those undertaking IVF and improve outcomes. More research is required on the impact of vitamin D on fertility in people with PCOS.
Improves mood
One of the ways that vitamin D is good for PCOS is that it may help in improving your mood.
Research in this area has shown that people with PCOS are at a higher risk of mood and anxiety disorders such as depression. A systematic review and meta-analysis found that vitamin D supplementation had positive effects on people with major depressive disorder and reduced negative emotions.
More research is required on the impact of vitamin D supplementation on mood in people with PCOS specifically, but the evidence so far is promising.

Sources of vitamin D
Vitamin D can be found in some foods naturally, plus some food is fortified with vitamin D. Vitamin D can also be supplemented.
Food sources of vitamin D
There are some foods that contain vitamin D, but these are in small amounts. This includes oily fish such as salmon, sardines, herring and mackerel. Plus, red meat, liver and egg yolks. Some foods are fortified with vitamin D such as some fat spreads and breakfast cereals.
Vitamin D supplements
Because vitamin D is converted in the body from sunlight, it can be challenging to get enough vitamin D during the winter months from food alone. Plus, if someone has dark skin, doesn’t get much sun on their skin or is at risk of deficiency, then supplementing all year round may be necessary.
Therefore may be suggested that people with PCOS should take vitamin D supplements all year round. Vitamin D supplements come in spray and tablet form.
Speak to your doctor or healthcare provider before taking supplements.
Vitamin D dosage
Adults require 10 micrograms (also sometimes written as 400 IU) of vitamin D per day during the winter, including pregnant and breastfeeding people. Those at risk of vitamin D deficiency (people with dark skin, those who cover their bodies fully with clothing, those who don’t go outside in sunlight often for example) may need to take vitamin D supplements throughout the year.
As with any supplement, speak to your doctor to determine your ideal dose and dosage schedule.
Signs of low vitamin D or deficiency
The main symptoms of low vitamin D are unexplained tiredness and bone aches or pains. Other less common symptoms may be poor sleep, low mood, hair loss, muscle weakness, a loss of appetite or getting sick more easily.
If you believe you may be deficient in vitamin D, speak to your doctor and request a blood test. People with dark skin and those who cover up their bodies fully with clothing or don’t go outside in sunlight often are more at risk of vitamin D deficiency.
Side effects of vitamin D supplementation
Supplementing with too much vitamin D can cause too much calcium to build up in the body. This can damage the kidneys and heart, and weaken bones. No more than 100 micrograms (4,000 IU) of vitamin D a day should be taken.
Best Vitamin D Supplement for PCOS
We’ve selected two of the highest-rated vitamin D supplements for people with PCOS.
Ultra Vitamin D provides effective levels of the preferred form of vitamin D3 (cholecalciferol).
- 96 tablets
- 25ug
- Vegetarian
BetterYou D3000 + Vitamin D + K2 Spray 12ml
- 30 daily servings
- Vegan
- 75ug of vitamin D3 plus 75ug of vitamin K2
- Peppermint flavour
Key takeaways: vitamin D and PCOS
Vitamin D is essential for a variety of roles in the body including calcium and phosphate regulation. It appears that people with PCOS are more likely to be deficient in vitamin D than the general population. Vitamin D supplementation appears to be beneficial for PCOS as it may improve fertility outcomes, improve insulin resistance and boost mood.
Everyone in the Northern Hemisphere should supplement vitamin D in the winter months, but it may be helpful for people with PCOS to supplement with vitamin D throughout the year. Always speak to a healthcare professional if you believe you are deficient in vitamin D.