Vitamin D and PCOS

Key Takeaways

• Vitamin D plays a role in bone health, immune function and metabolic processes in the body.
• Vitamin D deficiency appears to be relatively common in individuals with PCOS and in the general population.
• Sunlight exposure between April and September is the main natural source of vitamin D in the UK.
• Dietary sources include oily fish, egg yolks and fortified foods.
• Maintaining adequate vitamin D levels may support overall health alongside nutrition, movement and sleep.

Vitamin D is often associated with bone health, yet its role in the body extends far beyond maintaining strong bones.

In recent years, researchers have explored how vitamin D may influence metabolic health, inflammation and hormone regulation. This has led to increasing interest in its potential relevance for people living with polycystic ovary syndrome (PCOS).

Vitamin D deficiency is relatively common in the general population, particularly in northern climates such as the UK where sunlight exposure is limited during the winter months. Studies suggest that deficiency may be even more common among individuals with PCOS.

Understanding the relationship between vitamin D and PCOS may help highlight another important piece of the lifestyle puzzle when supporting long-term health.

Why Vitamin D Levels May Be Lower in PCOS

Vitamin D is produced in the skin following exposure to sunlight and can also be obtained in smaller amounts from certain foods.

Several factors may contribute to lower vitamin D levels in individuals with PCOS.

Firstly, vitamin D is fat-soluble, meaning it can be stored in body fat. Research suggests that higher body fat levels may reduce circulating vitamin D levels, which may partly explain why deficiency is more common in metabolic conditions.

Secondly, insulin resistance, which is common in PCOS, may influence vitamin D metabolism and signalling pathways within the body.

Lifestyle factors may also play a role. Many people spend large portions of the day indoors, particularly during the colder months, which can limit sunlight exposure.

Some groups may also have a higher risk of vitamin D deficiency. Individuals with darker skin pigmentation may require longer sun exposure to produce the same amount of vitamin D as those with lighter skin. This is because melanin reduces the skin’s ability to produce vitamin D from sunlight.

Vitamin D deficiency is also more common in people who cover most of their skin for cultural or religious reasons, or those who spend very little time outdoors.

For individuals living in northern Europe, including the UK, vitamin D levels often decline during autumn and winter when UVB radiation is insufficient for vitamin D production.

Vitamin D, Insulin Resistance and Metabolic Health

One of the most widely studied areas of vitamin D research in PCOS relates to insulin resistance.

Vitamin D receptors are present in many tissues involved in glucose metabolism, including pancreatic cells that produce insulin and muscle cells that help regulate glucose uptake.

Some studies suggest that adequate vitamin D levels may support insulin sensitivity and glucose metabolism, although research findings remain mixed.

Vitamin D may also influence inflammation. Chronic low-grade inflammation is often observed in PCOS and may contribute to metabolic disturbances.

While vitamin D alone is unlikely to resolve metabolic challenges, ensuring adequate levels may form part of a broader lifestyle approach that includes balanced nutrition, movement and sleep.

You can learn more about the role of exercise in supporting metabolic health in our article on strength training and PCOS.

Vitamin D, Mood and Wellbeing

PCOS is associated with higher rates of anxiety, low mood and fatigue.

While these experiences are influenced by many factors, vitamin D may play a role in brain function and mood regulation.

Vitamin D receptors are present in several regions of the brain involved in emotional regulation. Some research has explored associations between low vitamin D levels and mood disturbances, although more studies are needed to understand these relationships fully.

Supporting overall nutritional status, including vitamin D, may therefore be an important part of a holistic approach to wellbeing in PCOS.

How Sunlight Supports Vitamin D Production

Sunlight is the most significant source of vitamin D for many people.

When skin is exposed to ultraviolet B (UVB) rays from the sun, the body begins producing vitamin D. In the UK, this process typically occurs between April and September, when the sun is strong enough to stimulate vitamin D production.

Short periods of sunlight exposure during spring and summer can help support vitamin D levels. For many people, exposing the face, arms or legs to sunlight for a brief period during the middle of the day may contribute to vitamin D production.

The exact amount of time needed can vary depending on several factors, including skin tone, time of day, season and geographical location. Individuals with darker skin may require longer exposure compared with those with lighter skin.

It is important to balance sunlight exposure with skin protection. Sunburn increases the risk of skin damage and skin cancer, so prolonged exposure without protection is not recommended.

Because sunlight exposure is limited in the UK for several months of the year, public health guidance recommends that adults consider vitamin D supplementation during autumn and winter.

Anyone concerned about their vitamin D status may wish to discuss testing or supplementation with their GP or you can book a call with us.

Food Sources of Vitamin D

Only a small number of foods naturally contain vitamin D. These include:

• Oily fish such as salmon, sardines and mackerel
• Egg yolks
• Liver
• Fortified foods such as some dairy alternatives or breakfast cereals

Because dietary sources are limited, sunlight exposure is typically the main source of vitamin D for many people.

Vitamin D and Long-Term Health

Vitamin D contributes to several processes relevant to PCOS, including bone health, muscle function and immune regulation.

Maintaining adequate levels may therefore support long-term wellbeing alongside other lifestyle strategies.

This includes regular movement, resistance exercise, balanced nutrition and sufficient sleep.

You can read more about the connection between hormones and skeletal health in our article on bone health and PCOS.

Frequently Asked Questions

Is vitamin D deficiency common in PCOS?

Some research suggests vitamin D deficiency may be more common among individuals with PCOS, particularly where insulin resistance or higher body fat levels are present. However, vitamin D deficiency is also common in the general population, particularly in northern countries with limited sunlight during winter.

Can vitamin D improve PCOS symptoms?

Vitamin D plays an important role in many processes in the body, including bone health, immune function and metabolism. Some research has explored its role in insulin sensitivity and inflammation in PCOS, but it should be viewed as one component of a broader lifestyle approach rather than a standalone solution.

How can I support my vitamin D levels naturally?

Sunlight exposure during spring and summer is the primary natural source of vitamin D for most people. Small amounts are also found in foods such as oily fish and egg yolks. In the UK, supplementation is commonly recommended during autumn and winter months due to reduced sunlight exposure.