Health expert Prof Tim Spector has come under fire from fellow scientists after he suggested people should stop using factor 50 sunscreen all year round.
Spector quoted a recent mouse study suggesting that vitamin D levels may be an important factor in cancer immunity and immunotherapy success, and says the research is “another reason to stop using SPF 50 year-round that our natural defenses block”.
However, a co-author of the study disputed such conclusions.
“Sunlight can help our bodies make vitamin D, but sun exposure is also a clear risk factor for skin cancer. Since we can also get vitamin D from diet, it is easy to prevent possible vitamin D deficiency while minimizing harmful sun exposure. Our study does not indicate that the application of sunscreen is in any way detrimental to health,” said Prof Caetano Reis e Sousa of the Francis Crick Institute.
Spector, who made the statement on X, saw that his post was initially marked with a context box that read: “The linked study is a pre-clinical study based on mice alone. The suggestion that this means that humans SPF- can reduce use is a big leap that is not evidence-based, and should be read with caution.” However, he subsequently re-posted on the platform.
The posts were met with a backlash from medical professionals.
“This is a terrifyingly inaccurate post that can cause great damage and even loss of life. Academic authorities with a large fan base should be more mindful than this,” Adriano Aguzzi, a professor and director of the Institute of Neuropathology at the University of Zurich, wrote on X.
Speaking to the Guardian, Spector reiterated his view.
“Studies has shown that lower levels of vitamin D in people with melanoma are associated with poorer outcomes and thicker tumors – a measure of the severity of the disease.”
“Other research showed that melanoma patients who went on a sunny vacation before diagnosis had less thick tumors. The same study showed that people who had sunny holidays after diagnosis were less likely to experience recurrence.”
Spector said the risk of developing melanoma is largely dependent on genetics.
“So while the vast majority of people in the UK don’t need to wear SPF 50 all year round, certain people need to be more careful if they intend to be in the sun for long periods of time. This individuals include those 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 for 365 days a year is probably excessive and will likely leave 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 mouse study to humans, a mistake made all the more serious by a random inference that we should use less sunscreen to reduce cancer risk,” he said.
“This flies in the face of 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, most recent high-quality trials and meta-analyses have found no effect of vitamin D on mortality, nor is there any evidence that sunscreen inhibits vitamin D production in anyway,” he added.
Antony Young, an emeritus professor of experimental photobiology at King’s College London, said there was no need to use sunscreen all year round in the UK – although the practice was unlikely to be harmful.
“The dose of ultraviolet B radiation needed to make vitamin D in the skin is much lower than that for sunburn,” he said.
Young added that while there were no studies on the effect of SPF 50 sunscreens on vitamin D, his own work showed that correct use of SPF 15 during a week’s sunny holiday in the Canary Islands prevented sunburn and yet allowed excellent vitamin D production.
“The problem is that people don’t use sunscreens correctly, which means that typical use of SPF 50 will give an SPF in the region of 15, so it’s unlikely to have a big effect on vitamin D,” he said. said.
This isn’t the first time Spector has had doubts about sunscreen. Write on X in 2022, he said that sunshine was responsible for only a small proportion of melanomas and death rates had not changed for 40 years. “But charities benefit doctors and sunscreen manufacturers,” he wrote.
