Cardiovascular disease (CVD) is a leading global health concern, largely driven by suboptimal lifestyles. Improving diet and physical activity is crucial for CVD prevention, yet many fail to meet recommended targets, particularly for fruit and vegetable (FV) consumption. Providing asymptomatic individuals with non-invasive vascular imaging results, such as coronary artery calcification (CAC) or carotid atherosclerosis, has shown promise in improving CVD risk factor control by influencing motivation, self-efficacy, and intentions. Studies have demonstrated positive impacts on blood pressure and lipid levels through improved medication adherence. However, evidence regarding the impact on dietary habits, specifically FV intake, remains limited. Abdominal aortic calcification (AAC), an indicator of structural vascular disease, is strongly linked to subclinical CVD and predicts future CVD events. Given the association between FV consumption and reduced AAC, this study aimed to investigate whether providing AAC results, along with educational resources, influences FV intake, overall diet quality, physical activity, and other CVD risk factors in older adults.

Existing research indicates a correlation between providing non-invasive vascular imaging results and improved cardiovascular risk factor control. Studies on coronary artery calcification (CAC) and carotid atherosclerosis have shown positive impacts on blood pressure and lipid levels, primarily by encouraging medication initiation and adherence. However, evidence on the impact of vascular imaging results on dietary changes, specifically fruit and vegetable intake, is sparse. A scoping review conducted by the research team highlighted limited evidence from randomized controlled trials (RCTs) on this topic. This study addresses this gap by focusing on the impact of providing abdominal aortic calcification (AAC) results, a readily available and easily interpretable marker of CVD risk, on dietary behavior in older adults.

This 12-week, two-arm, single-blind, parallel randomized controlled trial (RCT) enrolled 240 participants (aged 60-80) with abdominal aortic calcification (AAC) assessments. Participants were randomly assigned (1:1) to receive their AAC results with educational resources (AAC+Ed group) or educational resources alone (Control+Ed group). Both groups received educational materials on CVD risk control. Baseline and 12-week assessments included plasma carotenoid concentrations (biomarkers of FV intake), a food frequency questionnaire (FFQ), dietary quality (Dietary Guideline Index), physical activity levels (CHAMPS questionnaire), body weight, blood pressure, heart rate, lipid profile, glucose concentrations, and estimated CVD risk score. Linear mixed-effects regression was used to analyze between-group differences. The study employed a modified intention-to-treat analysis, including all randomized participants. Exploratory analyses investigated the correlation between baseline AAC scores and changes in outcomes.

No significant between-group differences were observed in primary outcomes (changes in plasma carotenoid concentrations and FV intake) at 12 weeks. Both groups showed substantial within-group improvements in FV intake. However, the provision of AAC results led to significant between-group differences in serum total cholesterol (−0.22 mmol/L [−0.41, −0.04]), non-HDL cholesterol (−0.19 mmol/L [−0.35, −0.03]), and estimated CVD risk score (−0.24% [−0.47, −0.02]). These improvements were driven by greater reductions in total cholesterol, non-HDL-C, and LDL-C in the AAC+Ed group. Non-fasting glucose concentrations also differed significantly between groups due to increases in the control group and no change in the intervention group. No significant between-group differences were found for other secondary outcomes (dietary quality, physical activity, body weight, blood pressure, heart rate). Exploratory analyses revealed an inverse association between baseline AAC scores and change in body weight in the AAC+Ed group, with those with higher AAC scores experiencing greater weight loss. A significant time by study wave interaction was observed for total carotenoid concentrations, suggesting a potential influence of COVID-19 restrictions on lifestyle behaviours.

The study's findings suggest that providing AAC results, while effective in improving some CVD risk factors (blood lipids), did not significantly impact fruit and vegetable intake in older adults. The lack of impact on dietary changes may be attributed to several factors, including the study's conduct during the COVID-19 pandemic, which might have influenced participants' behavior. The less established recognition of AAC as a CVD risk factor compared to CAC may also play a role. While no between-group differences in FV intake were seen, both groups showed significant within-group improvements, possibly due to the educational intervention and Hawthorne effect. The improvement in blood lipid concentrations observed in the AAC+Ed group aligns with findings from other studies using CAC and carotid ultrasound results. This improvement may be partially explained by the greater weight reduction observed in participants with higher AAC scores.

This RCT demonstrated that providing AAC results alongside education did not significantly improve fruit and vegetable intake compared to education alone. However, both groups showed substantial improvements, suggesting the educational intervention's effectiveness. Providing AAC results improved blood lipid levels, reducing CVD risk. Further research with larger samples, tailored dietary and lifestyle advice, and structured follow-ups is needed to explore AAC's impact on risk-reducing behaviors and mechanisms underlying these changes. Future studies should also consider the influence of the pandemic and the level of understanding and perceived threat associated with AAC.

Limitations include the virtual delivery of results due to COVID-19 restrictions, which might have affected participants' understanding. The use of FFQs, while less burdensome, has limitations in recall accuracy and portion size estimation. The study did not reach its target sample size, potentially impacting statistical power. The observed improvements in both groups also suggest a potential Hawthorne effect, which future studies should address through improved trial design.