Diet and premalignant lesions of the cervix: evidence of a protective role for folate, riboflavin, thiamin, and vitamin B12.

OBJECTIVE: A case-control study was conducted among a population of multiethnic women identified from clinics on Oahu, Hawaii between 1992 and 1996 to explore the relationship between diet and cervical dysplasia.

METHODS: Two-hundred and fourteen women with biopsy-confirmed high and low grade squamous intraepithelial lesions of the cervix (SIL) and 271 controls were identified. Exfoliated cervical cells were collected for HPV DNA testing. Surveys were administered to assess non-dietary risk factors and intake of nutrients from over 250 specific food items as well as nutritional supplements.

RESULTS: Riboflavin and thiamin from food sources, vitamin B12 supplements, and total (food and supplements) folate displayed inverse, dose-responsive associations with high-grade SIL (HSIL). Riboflavin from food sources and total folate also demonstrated inverse, dose-responsive associations with low-grade SIL (LSIL). The odds ratios for LSIL and HSIL were reduced by 50-90% for the highest compared to the lowest levels of intake of these nutrients. A number of major food sources of these vitamins, including all types of breads, bran cereal, and fruit juice, also demonstrated inverse associations with HSIL. There was some evidence that the increased risk of HSIL associated with low nutrient intake was most pronounced among drinkers and smokers.

CONCLUSIONS: This investigation provides evidence that thiamin, riboflavin, folate, and vitamin B12 may play a protective role in cervical carcinogenesis.