A long term study by researchers from Harvard School of Public Health, Boston, have shown that men consuming high quantities of citrus fruits and vegetables are at a 30-40 percent lower risk of developing oral pre-malignant lesions, which in 16 to 40 percent cases transform into cancer. The researchers examined fruit and vegetable consumption and the rate of oral pre-malignant lesions among 42,311 U.S. men enrolled in the Health Professionals Follow-up Study.

The diet of subjects was assessed every four years using food frequency questionnaires. Researchers noted that a total of 207 cases of oral pre-malignant lesions occurred between 1986 and 2002.

They found that men who consumed greater quantities of citrus fruit, citrus fruit juice and Vitamin C-rich fruits and vegetables were at 30-40 percent lower risk of contracting oral pre-malignant lesions.

Overall, the "dietary recommendations to increase consumption of fruits are appropriate for preventing oral pre-cancer and cancer," Dr. Kaumudi Joshipura and team concludes.

The findings of the study are published in September issue of American Journal of Epidemiology.