In fact, only three of the 15 studies in the meta-analysis de Maleissye et al. have conducted showed a beneficial effect of sunscreen use on the count of melanocytic nevi, while eight studies reported a positive association between sunscreen application and MN count.
Interestingly, Goodson et al. have reported in 2009, already, that a single dose of N-acetyl cysteine (NAC) could provide an alternative to classic coetaneous means of sun protection (Goodson. 2009). Moreover, its inhibitory effect on the UV-induced glutathione depletion could be potentiated by the administration of other dietary anti-oxidants that strengthen the endogenous antioxidant system (Camp. 2011).
Camp WL, Turnham JW, Athar M, Elmets CA. New agents for prevention of ultraviolet-induced nonmelanoma skin cancer. Semin Cutan Med Surg. 2011 Mar;30(1):6-13.
de Maleissye MF, Beauchet A, Saiag P, Corrêa M, Godin-Beeckmann S, Haeffelin M, Mahé E. Sunscreen Use and Melanocytic Nevi in Children: A Systematic Review. Pediatr Dermatol. 2012 Sep 20.
Goodson AG, Cotter MA, Cassidy P, Wade M, Florell SR, Liu T, Boucher KM, Grossman D. Use of oral N-acetylcysteine for protection of melanocytic nevi against UV-induced oxidative stress: towards a novel paradigm for melanoma chemoprevention. Clin Cancer Res. 2009 Dec 1;15(23):7434-40.