Longitudinal associations of fiber, vegetable, and fruit intake with quality of life and fatigue in colorectal cancer survivors up to 24 months posttreatment

The increasing colorectal cancer (CRC) survivor population highlights the need for dietary recommendations in order to enhance health-related quality of life (HRQoL) and alleviate symptoms of fatigue, chemotherapy-induced peripheral neuropathy (CIPN), and gastrointestinal problems. Because of the therapeutic potential of dietary fiber on the gut, we aim to assess longitudinal associations of postdiagnostic dietary fiber, fruit, and vegetable intake, a major source of dietary fiber, with HRQoL, fatigue, CIPN, and gastrointestinal symptoms in CRC survivors from 6 wk to 24 mo posttreatment. In a prospective cohort among stage I–III CRC survivors (n = 459), 5 repeated study measurements between diagnosis and 24 mo posttreatment were executed. Dietary fiber intake and fruit and vegetable intake were measured by 7-d dietary records. HRQoL, fatigue, CIPN, and gastrointestinal symptoms were measured by validated questionnaires. We applied confounder-adjusted linear mixed models to analyze longitudinal associations from 6 wk until 24 mo posttreatment and used hybrid models to disentangle the overall association into intraindividual changes and interindividual differences over time. Higher dietary fiber intake and fruit and vegetable intake were longitudinally associated with statistically significant better physical functioning and less fatigue. Intraindividual analyses showed that an increase of 10 g/d in dietary fiber within individuals over time was associated with better physical functioning (β: 2.3; 95% CI: 0.1, 4.4), role functioning (ability to perform daily activities; 5.9; 1.5, 10.3), and less fatigue (−4.1; −7.7, −0.5). An average increase in fruit and vegetable intake of 100 g/d between individuals over time was predominantly associated with less fatigue (−2.2; −4.2, −0.3). No associations were found with CIPN and gastrointestinal symptoms. Our results suggest that increasing dietary fiber, fruit, and vegetable intake is related to better physical and role functioning and less fatigue in the first 2 y after the end of treatment for CRC.