Mediators of fruit and vegetable consumption among colorectal cancer survivors

Abstract

Introduction: Due to early detection and treatment, survival from colorectal cancer (CRC) diagnosis has been steadily increasing. A CRC diagnosis could be considered a "teachable moment," a time when interventionists might successfully promote dietary changes. CRC interventions with tailored print communication (TPC) and telephone motivational interviewing (TMI) have been shown to be effective in promoting fruit and vegetable consumption (FVC) among CRC survivors. However, little is known about how these interventions work to exert their effect. This study investigated whether information processes mediate the relationship between a CRC intervention and FVC among CRC survivors.

Methods: This research used data from NC STRIDES, a study that tested the efficacy of two CRC intervention strategies to promote FVC among CRC survivors. Participants were randomized to control, TPC, TMI, or combined (TPC+TMI). Structural equation models were constructed to analyze data from 266 CRC survivors using two different measures of FVC, a 35-item and a 2-item measure.

Results: Two information processes, relevance of communication and trust in the communication, mediated the effect of TPC+TMI on FVC for both 35-item and 2-item measures. TPC+TMI was significantly associated with relevance of communication, and perceiving greater relevance was significantly related to trust in the communication. Trust was significantly related to FVC.

Discussion: Information processes, including relevance and trust in the communication, serve as mediators of the relationship between the CRC intervention and FVC.

Implications for cancer survivors: Future intervention research should investigate ways to enhance relevance of communication and trust in interventions with CRC survivors.

Figure 1

Conceptual model depicting the relationship between intervention, information processes, and fruit and vegetable consumption

Figure 2

Path diagram of model testing information processes as mediators of the association between intervention and 35-item measure fruit and vegetable consumption, adjusting for baseline fruit and vegetable consumption. Unstandardized β weights for variables entered into the model are shown. Significant relationships are indicated by asterisks (*p < .05, **p < .001).

Figure 3

Path diagram of model testing information processes as mediators of the association between intervention and 2-item measure fruit and vegetable consumption, adjusting for baseline fruit and vegetable consumption. Unstandardized β weights for variables entered into the model are shown. Significant relationships are indicated by asterisks (*p < .05, **p < .001).