By Claire Hosking

Claire Hosking  N.D. 

Specialist Naturopath – Holistic Nutritionist – Herbalist 

Firstly, I would love to share some exciting news. I am currently in the process of writing our first hormone program in which one of the key areas of focus is Polycystic Ovarian Syndrome (PCOS).  


PCOS is an endocrine disorder that affects the female reproductive system potentially causing irregular or absent cycles, hirsutism (excessive hair growth), acne, weight gain and infertility.  

While there are many causes and drivers of PCOS, with winter fast approaching, I wanted to talk about one of them, namely vitamin D which decreases in winter.

Image credit: Erik Holt Photography

Over recent years, many studies have shown that vitamin D deficiency may be involved in the development of insulin resistance, metabolic syndrome and a higher BMI all of which are commonly associated with ovulatory dysfunction found in PCOS individuals.  

While the mechanism is not entirely clear, vitamin D may have a beneficial effect on insulin either directly or by stimulating the expression of insulin receptors.

Vitamin D is completely different than most other vitamins. In fact, it’s a steroid hormone produced from cholesterol when your skin is exposed to the sun. For this reason, vitamin D is often referred to as ‘the sunshine vitamin.’

Did you know that according to the Australian Bureau of Statistics 1 in 4 people are vitamin D deficient?

Below are some suggested sources of vitamin D:


Your ideal time in Victoria to produce adequate vitamin D is in the warmer months of the year when the sun has a higher UV strength. Ideally in the southern states of Australia from September to April you can manufacture vitamin D with just 10 – 15 minutes of sun exposure outside of the high UV times. (i.e. before 10am and after 3pm).  This will deliver a safe level of sun exposure. Please remember this short timeframe must be devoid of sunscreen as it blocks the production of vitamin D. 

While you can still produce vitamin D during the colder months, the skin exposure time is much higher and much less realistic given the change in weather patterns.  It is normally recommended to focus on your careful sun exposure in Summer to help ensure that you have adequate vitamin D levels for winter. 


While sunshine is still the preferred choice of production of vitamin D, you are able to obtain some from foods. Generally, it comes from the following sources:

  1. Fatty fish: Salmon, tuna, and mackerel are some of the best sources of vitamin D
  2. Cod liver oil: an inexpensive and easily accessed supplement
  1. Egg yolks: The yolks of eggs are a good source of vitamin D
  2. Mushrooms: Some types of mushrooms, such as shiitake mushrooms, contain a small amount of vitamin D when exposed to UV light.
  3. Fortified foods: Many foods are fortified with vitamin D such as good quality, full fat dairy.


Supplementation (particularly in winter) may be an option to help support your optimal health.  However, there are many things for you to consider when supplementing. Correct and safe dosage levels will be individual for each person and it is important that adequate magnesium is available for vitamin D metabolism. 

When supplementing vitamin D it is important to make sure you have the right form.  Vitamin D2 (ergocalciferol) is produced by plants and fungi and vitamin D3 (cholecalciferol) is produced in animals.  Due to metabolisation by the liver, vitamin D3 has been found to be more effective at raising blood levels than vitamin D2.  If your liver is not healthy, you may have trouble creating the activated and more powerful form of vitamin D3.

If this is the case, scientists have recently created the activated form of vitamin D3 for supplementation. This new form very quickly restores healthy vitamin D status and ensures its subsequent benefits (if you have trouble finding this form, you can access it from our clinic).

Some studies have also suggested that vitamin D supplementation may improve certain aspects of PCOS, such as insulin resistance and menstrual irregularity. However, more research is needed to determine the optimal dosage and duration of vitamin D supplementation for women with PCOS.

It is always a good idea to make sure you enlist a health professional qualified to assess your vitamin D status and needs. I can help you to check your vitamin D status by referring you for pathology testing and then advise you of the correct type and dosage that you require.

I would love to discuss how Naturopathy can support you with Polycystic Ovarian Syndrome (PCOS).

Please feel free to make an appointment by calling our reception team on 03 5221 8220.

In health and happiness,



Esmail Mohammad Alayed Albarri, 1 ,* Ahmed Sameer Alnuaimi, 2 and Doaa Abdelghani 1 Effectiveness of vitamin D2 compared with vitamin D3 replacement therapy in a primary healthcare setting: a retrospective cohort study

Chih-Chien Sung, 1 Min-Tser Liao, 2 Kuo-Cheng Lu, 3 and Chia-Chao Wu 1 ,‘Role of Vitamin D in Insulin Resistance,’ J Biomed Biotechnol. 2012; 2012: 634195.

Claire Hosking

Specialist Naturopath, Holistic Nutritionist, Herbalist

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