Fruits and vegetables are important components of a healthy diet, but intakes in most Western countries are well below the recommended five servings a day. Men in particular are eating too little. The aim of this study is to understand the processes underlying this gender difference. Fruit and vegetable intake, nutrition knowledge, taste preferences, attitudes to fruit and vegetable intake, and dieting status, were assessed in a simple questionnaire in 1,024 older adults attending population-based cancer screening across the UK. The results confirmed the pattern of men consuming fewer servings of fruit and vegetables daily than women (2.52 vs 3.47; p<0.01). Fewer men than women knew the current recommendations for fruit and vegetable intake, and fewer were aware of the links between fruit and vegetable consumption and disease prevention. Women rated their liking for vegetables but not fruit higher, and there were no differences in attitudes. Men were less likely to be dieting to lose weight. Multivariate analysis showed that the gender difference in intake was substantially attenuated by controlling for nutrition knowledge. There were no significant attenuating effects of preferences, attitudes or dieting status. These results indicate that men's poorer nutrition knowledge explains a significant part of their lower intake of fruit and vegetables.