Vitamin D: The Sunshine Vitamin

As the winter months roll in, we say goodbye to readily available sunshine, and with that: vitamin D. Synthesised in our skin upon sun exposure, this important vitamin becomes harder to get as we layer up and the clouds close over. Even in summer with the increased risk of sunburn and skin cancers, our sun exposure is restricted.

Our clinical nutritionist, Nicole, tells us why this vitamin is so important and strategies to optimise intake throughout winter.

They say sunshine is the best medicine.


Vitamin D is perhaps most well known for its role in calcium absorption to promote bone health. Sufficient vitamin D intake is required to maintain strong healthy bones and decrease the risk of developing bone disorders such as rickets in children and osteoporosis in adults.

This fat soluble vitamin also plays a crucial role in our immune system. Vitamin D has been shown to modulate various immune responses of the body due to the presence of vitamin D receptors on certain immune cells. A deficiency in vitamin D has been linked to an increased vulnerability to infection and increased autoimmunity (essentially when the immune system attacks its own healthy cells). Those with autoimmune conditions (rheumatoid arthritis, celiac disease, type 1 diabetes, inflammatory bowel disease, etc) may therefore have increased benefit from vitamin D supplementation.

Vitamin D also plays a critical role in mood and has been suggested to help with depression, particularly during winter for those who suffer from seasonal affective disorder (SAD). SAD is characterised by low mood and increased stress during the autumn and winter months only. Recent studies have researched the association between vitamin D and seasonal affective disorder and have found vitamin D supplementation to be promising in relieving feelings of depression.  


During May to August, the Ministry of Health recommend still getting some sun exposure – ideally a walk or outdoor activity between the hours of 11am and 3pm. The skin can’t synthesise vitamin D while you are wearing sunscreen, which can make it difficult to get a safe sun exposure. Fortunately, vitamin D can be synthesised in less time than it takes for skin damage to occur. In order to obtain adequate sun exposure, and protect your skin, aim for about 15 minutes sun exposure (less if you have fair skin or increased risk of skin cancer) before applying sunscreen. We recommend using a natural, ultra-gentle sunscreen which is safe for the whole family, such as Oasis Sun.

If you have darker skin tone, are of older age, have increased risk of skin cancer or are taking certain medications, your capacity for sun exposure and/or vitamin D synthesis may be hindered. In addition to this environmental factors such as location and air pollution also play a role in the effectiveness of obtaining vitamin D from the sun. In these situations, vitamin D supplementation may be required to maintain good health.

Unfortunately, very few foods naturally contain vitamin D. Small amounts can be found in the following:

  • Oily fish (salmon, tuna, mackerel, sardines)
  • Dairy products  
  • Egg yolks
  • Liver

If safe sun exposure, or eating adequate amounts of these foods is not possible, supplementation may be a more practical option. Cholecalciferol (vitamin D3) is the naturally occurring form which is synthesised in the skin via sun exposure. Most supplements contain this form.

Get in touch with one of our Tonic Health consultants or talk to a qualified health professional if you think that vitamin D supplementation might be beneficial to you.   


Aranow C. (2011). Vitamin D and the immune system. Journal of investigative medicine : the official publication of the American Federation for Clinical Research, 59(6), 881–886. doi:10.2310/JIM.0b013e31821b8755

Ministry of Health (2018). Vitamin D. Retrieved from

Penckofer, S., Kouba, J., Byrn, M., & Estwing Ferrans, C. (2010). Vitamin D and depression: where is all the sunshine?. Issues in mental health nursing, 31(6), 385–393. doi:10.3109/01612840903437657

Disclaimer: This blog post is intended for educational purposes only. Please do not use this information to diagnose or treat any health concerns you may have. This information is not intended to replace the advice given to you by a qualified health professional. Get in contact with a Tonic Health consultant or a relevant health professional if you need guidance on your individual health journey.