Health expert Professor Tim Spector is facing criticism from fellow scientists after advising against the use of SPF 50 sunscreen year-round. Spector’s recommendation stems from a recent mouse study, which suggests that vitamin D levels might play a role in cancer immunity and the success of immunotherapy. He argued that this study provides “another reason to stop using SPF 50 all year round, which blocks our natural defenses.”
However, one of the study’s co-authors disagreed with Spector’s interpretation. Professor Caetano Reis e Sousa from the Francis Crick Institute emphasized that while sunlight helps the body produce vitamin D, it is also a known risk factor for skin cancer. He noted that vitamin D can be obtained through diet, making it unnecessary to risk harmful sun exposure. “Our study does not suggest that sunscreen use is harmful to health,” he said.
Spector shared his views on X, where his post was flagged with a warning indicating that the mouse study does not justify reducing SPF use in humans. Despite this, he reposted his statement, which drew strong reactions from the medical community.
Professor Adriano Aguzzi from the University of Zurich labeled Spector’s post as dangerously misleading, stressing that public figures should be more responsible with their influence.
In an interview with The Guardian, Spector defended his stance, citing studies that link lower vitamin D levels in melanoma patients to worse outcomes. He mentioned research indicating that melanoma patients who had sun exposure before diagnosis had thinner tumors and fewer recurrences if they vacationed in sunny locations post-diagnosis. Spector believes genetics play a significant role in melanoma risk, and that while most people in the UK don’t need SPF 50 year-round, those with a family history of melanoma or fair skin should be cautious. He suggested that constant use of SPF 50 might lead to vitamin D deficiency.
Dr. David Robert Grimes criticized Spector’s advice, calling it “wrong-headed” to apply findings from mouse studies to humans. He pointed out that extensive research supports the effectiveness of sunscreen in preventing skin cancer and noted that recent studies show no significant impact of vitamin D on mortality. Grimes also stated there is no evidence that sunscreen use inhibits vitamin D production.
Professor Antony Young from King’s College London agreed that sunscreen isn’t needed year-round in the UK, but added that it isn’t harmful either. He explained that the amount of UVB radiation needed for vitamin D production is much less than what’s required to cause sunburn. Young’s research demonstrated that using SPF 15 during a sunny holiday prevented sunburn while still allowing for sufficient vitamin D production. He pointed out that most people do not apply sunscreen correctly, meaning that SPF 50 often provides much lower protection, equivalent to SPF 15, which is unlikely to significantly affect vitamin D levels.
Spector has previously questioned the benefits of sunscreen. In a 2022 post on X, he argued that sun exposure contributes minimally to melanoma rates, which have remained steady for decades, suggesting that some parties benefit financially from promoting sunscreen use.
