Looking for the best vitamin D supplement for PCOS?
Polycystic ovarian syndrome (PCOS) is a condition that affects many women and often leads to irregular periods, hormone imbalances, and fertility issues. Vitamin D deficiency is common in women with PCOS, and growing research suggests that low levels of vitamin D may play a role in worsening symptoms. But with so much conflicting advice out there, it’s easy to feel stuck.
If you’re living with PCOS, you’ve probably found yourself down a rabbit hole of supplements, wondering: Which ones actually help? Do I really need to take vitamin D — and if so, is it just a winter thing, or should I take it all year round?
In this blog, we’ll break it down clearly - exploring how vitamin D supplementation may help with PCOS symptoms, the best type of vitamin D to take, how much you need, and what to look for in a quality supplement.
What is Vitamin D?
Vitamin D is sometimes known as the ‘sunshine vitamin’, due to our bodies ability to produce vitamin D from exposure to sunlight on our skin.
Certain food sources such as fatty fish (e.g. salmon, sardines, trout or mackerel), eggs, liver, and fortified foods (e.g. breakfast cereals, bread, milks, spreads/butter) can provide us with vitamin D, however, not enough to meet the recommended daily requirements without sunlight or supplementation (1).
Due to a lack of sunlight, everyone in the UK is recommended to supplement their diet with vitamin D from October to March.
Vitamin D is important for many processes in the body, including supporting the absorption of calcium - for strong bones and heart health- and phosphorus - again for strong bones, teeth and energy production (1), and helping the development of follicles in the ovaries (2).
Vitamin D deficiency
Those most at risk of vitamin D deficiency include:
Those who are not often outdoors, perhaps frail, or housebound.
Those who wear clothes that cover most of their skin when they are outside.
Those with darker skin, who may not produce as much vitamin D from sunlight.
In adults, the symptoms of vitamin D deficiency include (3):
Muscle cramps and weakness
Fatigue
Bone pain
Mood changes or depression
Recommended Vitamin D3 Dosage (for adults):
Vitamin D and PCOS
Vitamin D plays an important role in women’s reproductive health, including having a link to PCOS (2). A study on 256 women with PCOS, found that over 70% of them were vitamin D deficient and a further 20% had insufficient levels of vitamin D (4). Other studies, such as one carried out in China, also found people with PCOS had much lower levels of vitamin D, than the general population (5).
Research shows that vitamin D may help with the following:
Improve insulin levels: Insulin resistance is often a problem in those with PCOS, and can contribute to weight gain (6). In an analysis of multiple controlled trials, people with PCOS who were supplemented with vitamin D had better insulin levels - meaning their blood sugar levels were more controlled when they took the vitamin D supplement.
Lower testosterone: High levels of testosterone are often found in people with PCOS, and can lead to symptoms such as acne and excess hair growth. The analysis also found that the vitamin D supplement helped lower testosterone in the body (6).
Lower cholesterol: PCOS is also linked to high cholesterol levels. The studies reviewed found that those who took the vitamin D supplements had lower levels of ’bad’ cholesterol in their blood (6).
Reduce inflammation: A study following 40 women for 8 weeks found that those who took a vitamin D supplement, had lower levels of inflammation markers in their blood, than those who didn't supplement (7).
Improve symptoms and regularity of the menstrual cycle: In a small study, over 75% of women with PCOS and low vitamin D levels, who took vitamin D and calcium supplements, saw improvements in their menstrual cycles, with a few even conceiving during the supplement study (8).
Boost fertility: In a meta analysis of 28 studies, research found that people with PCOS taking vitamin D supplements had higher rates of ovulation and pregnancy, than those who didn’t take a vitamin D supplement (9).
Vitamin D Supplements & PCOS
Given that vitamin D deficiency is common in people with PCOS and studies have shown improvements in insulin levels, testosterone levels and fertility, taking a vitamin D supplement all year round is likely to be beneficial.
There are 2 forms of vitamin D - D2 and D3. The most bioavailable and effective form of vitamin D supplementation to take is, Vitamin D3.
Why Vitamin D3?
Better absorbed and used by the body compared to Vitamin D2.
More effective at raising and maintaining overall vitamin D levels.
For even better absorption, you should try to take your supplement with a meal containing fats e.g. avocado, nuts, seeds, olive oil, as vitamin D is a fat-soluble vitamin.
Many supplements now combine Vitamin D3 with K2, which can help to maximise calcium absorption.
Recommended Vitamin D3 Dosage for PCOS- Specific support:
Studies often use doses between 2,000–4,000 IU/day (10) in women with PCOS to help improve insulin resistance, hormone balance, and menstrual regularity.
The best way to know what dose of vitamin D is best for you is by testing your vitamin D levels, through a 25 (OH)D blood test. If you are unsure of how much vitamin D to supplement with then speak to a women’s health dietitian for personalised advice.
Some suggestions for the best Vitamin D supplement for PCOS
Here are some brands that sell a high-quality Vitamin D supplement that you may want to try. Factors to consider when deciding whether a vitamin D supplement is ‘high-quality’ are:
Whether the brand uses 3rd party testing to ensure the safety and purity of the supplement
Supplements that use the D3 form of vitamin D
Supplements with minimal fillers or additives
Here are some recommendations:
Better Vits: Vitamin D3 with K2
Better You: Vitamin D3 and K2 oral spray (easy to use if you don’t get on with tablets)
In summary, women with PCOS are at greater risk of Vitamin D deficiency, and may find improvements in their menstrual cycle, blood sugar control and fertility by taking a vitamin D supplement.
Vitamin D supplements are just one of the supplements that you may want to include in your diet. You can read more about the other supplements below: