The Association between Dietary Folate and Vitamin B12 Intake and Genital Human Papillomavirus (HPV) Infection in Men

Abstract

Human papillomavirus (HPV) infection, which is an established cause of venereal warts and anogenital carcinoma, is one of the most prevalent sexually transmitted infections worldwide. Most HPV infections are asymptomatic, suggesting that other co-factors might play a role in the progression from infections to HPV-related diseases. Nutritional status is known to influence the immune system and alter host defense mechanisms, so it may be a determinant factor of the body’s cellular and biological response toward HPV infection. This dissertation presents an analysis which aims to understand the role of dietary intake – as a proxy of nutritional status – and the natural history of HPV infection in men. The first research question focuses on the association between dietary folate and vitamin B12 intake and persistent genotype specific HPV infections. The acquisition and clearance of genotype specific HPV infections and dietary folate and vitamin B12 intake are investigated in the second and third research question. All the analyses accounted for potential confounders such as energy intake, age, and risky sexual behaviors. This dissertation utilized data from the Hawaiʻi HPV male longitudinal study, which followed 445 adult men between 2004-2006. Compared to those with the highest intake level, our analyses did not yield strong evidence to support our hypothesis that men who consumed less dietary folate and vitamin B12 were at a higher risk of genotype specific HPV infections. However, we did find that men whose dietary folate and vitamin B12 intake were in the lowest and middle tertiles had higher odds of persistent genotype specific HPVs. Men whose dietary vitamin B12 intake was in the middle tertile had a higher risk of acquiring genotype specific HPVs. During the persistent stage of infection (> 130 days), men whose dietary folate intake was in the lowest tertile had a lower rate of any risk and oncogenic HPV clearance. Men whose dietary vitamin B12 intake was in the middle tertile had a lower rate of oncogenic HPV clearance.