If you have not already done so, please visit our How To summary page that discusses the approach that we use to select and present information on these pages

Sunlight and Vitamin D

If you have not already done so, please watch Dr Holic’s video on Vitamin D as it provides a great overview of the importance of vitamin D.

It seems that everyone has been told that vitamin D is important for strong bones as its has been used to cure “Rickets” which is a disease that weakens the bones.  However,  you have to be severely deficient in vitamin D to notice symptoms in your bones.

Studies have shown that Vitamin D has an effect on over 200 genes pointing to how widely it influences our bodily functions.  Some of the important functions include:

  • Important to bone growth – hence preventing “Rickets”
  • Important to immune function
  • Important to brain function and nerve growth
  • Important in protecting against inflammation

Having sufficient vitamin D has been shown to reduce your risk of getting cancer, multiple sclerosis (MS), dementia, erectile dysfunction, schizophrenia, and heart disease.  The list of conditions influenced by lack of vitamin D is constantly being added to.

The best source of vitamin D is your skin.  When your skin is exposed to ultraviolet radiation (specifically UV-B),  it produces this vitamin.  Other good dietary sources of vitamin D include cod liver oil and fatty fish such as salmon.  Eggs and liver have limited amounts of vitamin D.  So the average person would likely consider sunlight to be the best natural source.

A daily exposure to direct sunlight to arms and legs of around 10-15 minutes per day will provide sufficient vitamin D to maintain optimum levels in your body.  In Australia, certainly in the top half, you would try to avoid the period a couple of hours either side of midday due to the risk of sunburn.  Note that you need direct sunlight – it can’t be through windows as they block UV and you cannot be wearing sunscreen – though it may be best to apply it to your face.


Other than for the production of vitamin D, sunlight is also important in many ways:

  • Hormonal changes in the brain are triggered by sunlight and deficiency has been linked to mental health concerns.
  • Your “biological clock” is tied to exposure to sunlight.
  • The development of correctly shaped eyes to provide good uncorrected vision seems to be tied to sunlight exposure.

Sunlight seems to be generally important for good health and we recommend that you take advantage of this natural and free resource rather than reach for the supplements.  Science still has a long way to go to understand all of the effects of sunlight deficiency and some effects may be decades in the making.

Dangers of Sunlight

Excessive exposure to UV light, particularly where repeated damage has resulted, has been linked to skin cancer in population studies. How this causes cancer is not well understood, particularly as melanomas often develop in areas of the body that rarely get sun exposure.

We believe that you if you remove lifestyle factors of poor diet and lack of physical activity, you will be substantially less likely to get any form of cancer, including melanoma.   Just don’t overdo sunlight exposure.