It’s getting near summer again and we must be nearly due for the annual ‘slip slop slap’ message pounding the airwaves. Horror stories will emerge about people who did not follow this advice and ended up with melanoma, the most deadly type of skin cancer.
The unbalanced nature of the message has left many people believing that all sun is bad, and historically some experts have even gone so far as to tell us there is actually no safe level of sun exposure at all. What is true is that due to atmospheric factors, it takes less time to get sunburnt in New Zealand, and therefore we have a greater risk of getting skin cancers than people in other parts of the world. Two very vocal charities, the Cancer Society and Melanoma Foundation are behind the sunscreen message and because of their standing we tend not to question this advice.
Perhaps we should. What we were never told was that while sunscreens can protect us from premature aging and some less deadly types of skin cancer, there is scant evidence that it makes a difference to our chances of getting melanoma, yet avoiding melanoma is the primary reason we are told to use sunscreen in the first place.
The stay out of the sun/sunscreen message is further complicated because recent years have seen a boom in research on a once overlooked vitamin, vitamin D. Our primary source of vitamin D is from sunlight; our bodies make it when the sun falls on our skin. You may have heard a lot about vitamin D in the media recently, many studies have been published demonstrating that high levels of vitamin D correspond to significant reductions in the risk of getting at least 17 types of cancer as well as other diseases (some studies suggest a risk reduction of as much as 50%).
One of the reasons vitamin D has attracted so much international research is because of a fascinating local observation – New Zealand has high rates of melanoma, but we actually have a lower than average rate of death from it. It is hypothesised that while our harsh sun is likely causing an increase in incidences of melanoma, it is also causing us to make a lot more vitamin D which has a protective effect.
The ‘stay out of the sun message’ has led to widespread vitamin D deficiency. Apart from the (likely) increases of all sorts of cancers, other diseases such as rickets have also been making a comeback. Rickets is a bone disorder caused by low levels of vitamin D, some estimates suggest incidences of it have increased four-fold in recent times, mirroring the increase in sunscreen use.
There is evidence that sunscreen use can slow down signs of aging and reduce chances of getting less deadly (easily treatable) skin cancers, but even today, the evidence for protection against melanoma is very slim. Ian Wishart wrote in his vitamin D book that there was not a single study that suggested sunscreen use reduced incidences of melanoma and during his debate with Dr Jan Paulson of the Cancer Society she could not refute this point (watch the video below).
Given that fear of getting melanoma is the driver behind sunscreen sales, I would have thought that that the Cancer Society would be able to provide evidence to back up their claim. It is worth noting the conflict of interest as sunscreen manufacturers are big donors to the cancer charities.
Sunscreens do have their use, but the messages are confused. The downside is they block vitamin D creation which may be leading to increases in several other types of cancer. I think the message has to be get sun when you can – but avoid getting sunburnt. Get suspicious moles checked ASAP. Be careful of the sunscreen lotions you do use, as some have dangerous chemicals. The sun remains your best source of vitamin D and any harm that may be caused must be balanced against the protective effect against a host of cancers and other diseases.