Health expert Prof Tim Spector has come under fire from fellow scientists after suggesting people should stop using factor 50 sunscreen all year round.
Spector quoted a recent mouse study That suggests that vitamin D levels may be an important factor in cancer immunity and the success of immunotherapy, saying the study is “yet another reason to stop using SPF 50 year-round, which affects our natural defense blocks”.
However, a co-author of the study disputed such conclusions.
“Sunlight can help our bodies produce vitamin D, but sun exposure is also a clear risk factor for skin cancer. Since we can also get vitamin D from food, it is easy to prevent possible vitamin D deficiency while minimizing harmful sun exposure. Our study does not suggest that the application of sunscreen is in any way harmful to health,” says Prof. Caetano Reis e Sousa of the Francis Crick Institute.
Spector, who made the statement about The suggestion that this means people can reduce their use of SPF is a huge leap that is not evidence-based and should be read with caution.” However, he then reposted on the platform.
The messages received a response from medical professionals.
“This is a frighteningly inaccurate post that could cause enormous damage and even loss of life. Academic authorities with a large following should be more aware than this,” Adriano Aguzzi, professor and director of the Institute of Neuropathology at the University of Zurich, wrote on X.
Speaking to the Guardian, Spector reiterated his position.
“Studies to have shown that in people with melanoma, lower levels of vitamin D are associated with poorer outcomes and thicker tumors – a measure of disease severity.”
“Other research showed that melanoma patients who went on a sunny holiday before diagnosis had fewer thick tumors. The same study showed that people who had a sunny holiday after the diagnosis were less likely to have a recurrence.”
Spector said the risk of developing melanoma was largely dependent on genetics.
“So while the vast majority of people in Britain don’t need to wear SPF 50 all year round, some people do need to be more careful if they plan to be out in the sun for long periods of time. This individuals include people with a family history of melanoma, pale skin and freckles, and those with a large number of moles,” he said.
“But even for these individuals, wearing SPF 50 365 days a year is likely excessive, likely leaving them vitamin D deficient.”
Dr. David Robert Grimes, a scientist and author of The Irrational Ape, criticized Spector’s post.
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“It is completely wrong to extrapolate an exploratory study in mice to humans, an error made all the more egregious by the haphazard inference that we should use less sunscreen to reduce cancer risk,” he said.
“This goes against over 100 years of clear data linking sunlight to skin cancer, and sunscreen as a highly effective way to prevent skin cancer. To make matters worse, the latest high-quality studies and meta-analyses have found no effect of vitamin D on mortality, and there is no evidence that sunscreen inhibits vitamin D production anyway,” he added.
Antony Young, emeritus professor of experimental photobiology at King’s College London, said there is no need to use sunscreen all year round in Britain – although it is unlikely to be harmful.
“The dose of ultraviolet B radiation required to produce vitamin D in the skin is much lower than that required for sunburn,” he said.
Young added that while there was no research on the effect of SPF 50 sunscreens on vitamin D, his own work had shown that the correct use of SPF 15 during a sunny week-long holiday in the Canary Islands prevented sunburn and yet enabled excellent vitamin D production.
“The problem is that people are not using sunscreens properly, meaning that normal use of SPF 50 will give an SPF of around 15, making it unlikely to have a major effect on vitamin D,” he said.
It’s not the first time Spector has had doubts about sunscreen. To write on X in 2022, he stated that sunshine was only responsible for a small proportion of melanomas and that mortality rates had not changed in forty years. “But charity doctors and sunscreen manufacturers profit from it,” he wrote.