Keratinization is the process whereby the surface of the glans and remaining mucosa of the circumcised penis become dry, toughened and hard. Normally, the glans is covered by the foreskin, which moisturizes the area by transudation, keeping the surface of the glans and inner mucosa moist and supple. After circumcision, however, the glans and surrounding mucosa become permanently externalized, and they are exposed to the air and the constant abrasion of clothing. These areas dry out, causing layers of keratin to build, giving the glans and remaining mucosa a dry, leathery appearance and reducing sensation.
Keratin as "Protection"
It was hypothesized in the past that the layers of keratin resulting from circumcision provided a barrier of protection against sexually transmitted diseases. In 1986, the late Aaron J. Fink invented the idea, without any evidence, that circumcision could prevent the transmission of HIV, arguing that the hard and toughened glans of the circumcised male resisted infection, while the soft and sensitive foreskin and glans mucosa of the intact male were ports of entry.
Recent studies have shown this hypothesis to be false. One study found that there is "no difference between the keratinization of the inner and outer aspects of the adult male foreskin," and that "keratin layers alone were unlikely to explain why uncircumcised men are at higher risk for HIV infection, however keratinization of the glans penis was not measured." Another study found that "no difference can be clearly visualized between the inner and outer foreskin." Be that as it may, this hypothesis continues to be popular among researchers who advocate for circumcision as STD prevention.
Foreskin restoration by non-surgical means has been found to reduce keratinization and to improve appearance and sensation. When the glans penis is consistently covered and protected by a regrown foreskin the moisture and oils cause the keratinization to come off gradually. Increased sensation has been reported by many restored men.
- Fink, Aaron J. (1986): A possible Explanation for Heterosexual Male Infection with AIDS, in: NEJM. 315 (18): 1167. Retrieved 4 September 2020.
- Dinh, MH / M.D. McRaven / Z. Kelley / S. Penugonda / T.J. Hope (27 March 2010): Keratinization of the adult male foreskin and implications for male circumcision, in: AIDS. 24 (6): 899-906, PMID. Retrieved 7 June 2020.
- Rosenberg, Molly S. / FX Gómez-Olivé / Julia K Ronr / Kathleen Kahn / Till W Bärnighausen (1 August 2018): Are circumcised men safer sex partners? Findings from the HAALSI cohort in rural South Africa, in: PLOS ONE. 13 (8): e0201445, PMID, PMC, DOI. Retrieved 20 October 2019.