As for many other cancers, high consumption of fruit and vegetables is supposed to reduce the risk of ovarian cancer. In addition to being a major source of dietary vitamin C, folate, and fibre, fruits and vegetables also contain numerous other potentially anticarcinogenic phytochemicals (Park and Pezzuto, 2002). The majority of case–control studies (La Vecchia et al, 1987; Engle et al, 1991; Bertone et al, 2001; Bosetti et al, 2001; Cramer et al, 2001; McCann et al, 2001; Zhang et al, 2002; McCann et al, 2003), although not all (Shu et al, 1989; Salazar-Martinez et al, 2002), have suggested an inverse association of consumption of total vegetables or of certain subgroups of vegetables with ovarian cancer risk. In two prospective cohort studies that have reported results for consumption of total vegetables and ovarian cancer risk (Kushi et al, 1999; Fairfield et al, 2001), a nonsignificant approximately 25% reduction in ovarian cancer risk was observed for the highest in comparison with the lowest category of consumption. A recent comprehensive review of the literature on fruit and vegetable consumption and cancer by the IARC Working Group on the Evaluation of Cancer-Preventive Strategies (2003) concluded that ‘an increase in consumption of vegetables possibly reduces the risk of ovarian cancer’. In contrast to vegetable consumption, fruit consumption in case–control (Shu et al, 1989; Bosetti et al, 2001; McCann et al, 2001,2003; Salazar-Martinez et al, 2002; Zhang et al, 2002) and cohort studies (Kushi et al, 1999; Fairfield et al, 2001) of ovarian cancer have yielded conflicting results, with both inverse and positive associations.
We have therefore examined overall fruit and vegetable consumption as well as consumption of specific fruits and vegetables in relation to total ovarian cancer incidence and its subtypes in a large prospective population-based cohort of Swedish women.