The authors explained that fruits and vegetables have been extensively studied for their possible effects on the risk of cancer, including bladder cancer. Fruits and vegetables contain several nutrients, phytochemicals, as well as antioxidants which potentially protect from cancer.

According to the National Cancer Institute, there are approximately 72,570 new cancer bladder cases and 15,210 deaths caused by bladder cancer annually in the United States.

Song-Yi Park, PhD., and colleagues set out to determine what effect high fruit and vegetable intake might have on invasive bladder cancer risk.

The team carried out a prospective analysis involving 185,885 older adults who participated in the Multiethnic Cohort Study. The study was set up in 1993 to examine the relationship between dietary, lifestyle, genetic factors, and the risk of cancer.

The researchers gathered and analyzed data over a 12.5-year period. During that time 152 females and 429 males developed invasive bladder cancer.

After making adjustments for some variables which influence cancer risk, such as age, the scientists discovered that those with the lowest bladder cancer risk were women who ate the most fruits and vegetables.

Park and team found that:
Women with the highest yellow-orange vegetable intake had a 52% lower risk of developing invasive bladder cancer compared to women with the lowest consumption.
Women with the highest consumption of vitamins A, C, and E were the least likely to develop bladder cancer.
Fruit and vegetable consumption appeared to have no effect on male bladder cancer risk.

Park said, "Our study supports the fruit and vegetable recommendation for cancer prevention. However, further investigation is needed to understand and explain why the reduced cancer risk with higher consumption of fruits and vegetables was confined to only women."