Impact of provision of abdominal aortic calcification results on fruit and vegetable intake: 12-week randomized phase 2 controlled trial

Cardiovascular disease (CVD) is driven largely by suboptimal lifestyle behaviors; improving diet and physical activity is central to prevention. Despite public health campaigns, most people do not meet fruit and vegetable (FV) intake recommendations. Providing asymptomatic individuals with results of non-invasive vascular imaging (such as coronary artery calcification [CAC] or carotid atherosclerosis) may catalyze behavior change via enhanced motivation, self-efficacy, goal setting, and shared decision-making with health professionals. Prior studies show that visualization of vascular disease can improve CVD risk factor control (e.g., blood pressure, lipids) mainly through medication initiation and adherence, but randomized evidence for effects on FV intake and overall diet is limited. Abdominal aortic calcification (AAC) is an early structural marker of vascular disease, associated with subclinical CVD and predicts future CVD events and mortality. Higher FV intake and certain constituents have been associated with less extensive AAC. No prior studies had tested whether providing visual AAC results could improve FV intake, overall diet quality, physical activity, and other CVD risk factors. This randomized controlled trial evaluated whether providing AAC results alongside educational resources, compared with education alone, improves objective (plasma carotenoids) and subjective (FFQ) measures of FV intake and secondary cardiometabolic outcomes in adults aged 60–80 years.

Evidence indicates that visualizing vascular calcification (e.g., CAC, carotid plaques) can improve CVD risk factor control, likely via medication initiation/adherence and behavior change support. Scoping and systematic reviews have suggested potential benefits for lipid levels and blood pressure, with mixed or limited evidence for dietary behavior changes including FV intake. AAC, detectable on DXA-derived lateral spine images and other imaging modalities, correlates with generalized atherosclerosis and predicts CVD events and mortality. Observational studies in older adults link higher FV intake and specific dietary patterns/components (e.g., flavonoids, cruciferous vegetables, lower dietary inflammatory index) with less extensive AAC. However, before this study there were no RCTs testing whether disclosure of AAC imaging results influences FV consumption, diet quality, physical activity, or broader CVD risk factors.

Design: Two-arm, single-blind (assessors), parallel-group, 12-week randomized controlled trial (MODEL study), conducted in Perth, Western Australia. Registered at ANZCTR (ACTRN12618001087246). Ethics approved (ECU HREC 20513 HODGSON). The original pre-pandemic protocol was modified due to COVID-19 using CONSERVE 2021 guidance. Participants: Community-dwelling adults aged 60–80 years, ambulant, able to attend clinic visits and complete electronic questionnaires, with email/mobile access. Recruitment via newspaper ads. Exclusions followed the pre-specified protocol; prior participants in a terminated pre-COVID trial were ineligible. Three recruitment waves corresponded to COVID-19 phases: Wave 1 (Sep 2020–Apr 2021), Wave 2 (May–Sep 2021), Wave 3 (Oct 2021–May 2022). Randomization and blinding: 1:1 allocation to intervention (AAC results + education; AAC+Ed) or control (education only; Control+Ed) using Stata-generated block randomization (ralloc). Where partners enrolled, they were allocated within the same block. A blinded research assistant enrolled participants; an unblinded investigator assigned codes. Participants were unblinded; outcome assessors were blinded until study end. Interventions: Approximately 2 weeks post-baseline, all participants received an email with allocation and a ~12-min educational video covering CVD, diet, and physical activity recommendations with study goals: (1) increase fruit intake by ≥1 serve/day (150 g/d) and vegetable intake by ≥1 serve/day (75 g/d); (2) improve overall diet (reduce salt, sugar, processed foods; increase wholegrains and nuts); (3) increase physical activity and reduce sitting. An e-booklet and FAQs accompanied the video. AAC+Ed group additionally received their individualized AAC results at baseline (with IMAGES and explanatory graphics/letter tailored to AAC score: none, evidence [1–5], extensive [≥6]); Control+Ed received results after 12 weeks. Participants and their general practitioner (GP) received result letters. A scheduled 30-minute follow-up phone call by an unblinded investigator occurred the day results/emails were sent. Assessments: Baseline and 12 weeks at Sir Charles Gairdner Hospital Bone Density Unit. - AAC imaging: DXA lateral spine image; AAC24 semi-quantitative score (0–24) by an expert reader. - Diet: Validated FFQ (DQES v3.2), adapted to report intake over the prior 12 weeks. FV intake (g/d) summed across items; energy, alcohol, macro/micronutrients derived. Adherence to Australian Dietary Guidelines assessed via Dietary Guideline Index (DGI). - Objective biomarker: Non-fasting plasma carotenoids (α-carotene, β-carotene, β-cryptoxanthin, lutein; lycopene excluded from total) via HPLC; samples protected from light and stored at −80 °C. - Physical activity: CHAMPS questionnaire estimating total and moderate-to-vigorous hours/week. - Clinical measures: Body weight (kg), height, seated blood pressure and heart rate (automated; average of 4 of 5 readings). - Biochemistry: Serum triglycerides, total cholesterol, HDL-c, non-HDL-c, LDL-c, glucose (ARCHITECT assays). - CVD risk: 5-year risk estimated using the Australian CVD Risk calculator. - Medication and healthcare use: Electronic questionnaires captured prescription/non-prescription medication use, GP visits, tests, and procedures. Outcomes: Primary—12-week change in FV intake measured by plasma carotenoids and FFQ-estimated FV (g/day). Secondary—12-week changes in dietary quality (DGI), energy and nutrients, physical activity, body weight, BP, HR, lipid profile, glucose, 5-year CVD risk, and medication/healthcare use. Exploratory—associations between baseline AAC24 and changes in outcomes; subgroup comparisons by AAC presence (≥1 vs 0) within AAC+Ed. Sample size: Planned n=300 (150/group) to detect 20% difference in total carotenoids (0.45 µg/mL) and 40 g/day difference in FV intake at 80% power, α=0.05. Actual n completing = 227 (115 AAC+Ed; 112 Control+Ed) due to COVID constraints. Statistical analysis: Modified intention-to-treat including all randomized participants. Mixed-effects regression with fixed effects for group, time (baseline, 12 weeks), and group×time interaction tested between-group differences. Descriptive statistics for margins and SD/95% CI. Chi-square tests for categorical comparisons (medications/healthcare use). Exploratory adjustments for changes in lipid- or BP-lowering medications. Spearman correlations for AAC24 vs change in outcomes; independent t-tests for changes by AAC presence within AAC+Ed. α=0.05; no multiplicity adjustment (phase 2 effectiveness study).

- Participants: 240 randomized (AAC+Ed n=121; Control+Ed n=119); 227 (94%) completed 12 weeks. Mean age 67.8 ± 5.0 years; 57.5% female. Baseline AAC present in 57.1% overall. - Primary outcomes (12-week between-group differences): • Plasma carotenoids (total, excluding lycopene): mean net difference +0.03 µg/mL (95% CI −0.06, 0.13); Pinteraction=0.494. • FV intake (FFQ, g/day): mean net difference +18 g/day (95% CI −37, 72); Pinteraction=0.526. • Both groups had significant within-group increases: plasma carotenoids +0.17 (0.10, 0.24) µg/mL in AAC+Ed and +0.14 (0.07, 0.21) in Control+Ed; FV intake +92 (53, 130) g/day in AAC+Ed and +74 (35, 113) g/day in Control+Ed (each p<0.001). - Secondary dietary outcomes: • DGI increased within both groups with no between-group difference (mean net difference −0.78 [−2.74, 1.17]; p=0.433). • No between-group differences in energy or most nutrients; folate increased more in AAC+Ed (Supplementary Table 1). AAC+Ed showed within-group increases in fiber and decreases in saturated fat. - Physical activity and anthropometrics: • No between-group differences in total or moderate-to-vigorous physical activity. Body weight decreased similarly in both groups (~−0.6 kg); no significant between-group differences. • BP and heart rate: no significant between-group differences; HR decreased within both groups (~−3 to −4 bpm). - Lipids, glucose, and estimated CVD risk (between-group differences favoring AAC+Ed): • Total cholesterol: −0.22 mmol/L (−0.41, −0.04); p=0.015. • Non-HDL-c: −0.19 mmol/L (−0.35, −0.03); p=0.022. • LDL-c: −0.16 mmol/L (−0.31, 0.00); p=0.049. • Triglycerides: −0.10 mmol/L (−0.27, 0.05); p=0.200 (NS). • Glucose: −0.32 mmol/L (−0.55, −0.08); p=0.007, driven by increases in Control+Ed with no change in AAC+Ed. • 5-year Australian CVD risk: −0.24% (−0.47, −0.02); p=0.048. - Medication/healthcare use over 12 weeks: Similar proportions visited GPs, had blood tests, or procedures across groups. Lipid-lowering medication initiation occurred in 5 participants (all AAC+Ed); one discontinuation in Control+Ed. Antihypertensive initiation in 1 AAC+Ed and 2 Control+Ed; one discontinuation in Control+Ed. Adjusting analyses for medication changes did not materially alter lipid/glucose results. - Exploratory analyses: • Within AAC+Ed, higher baseline AAC24 associated with greater weight reduction; participants with AAC≥1 vs AAC=0 had greater reductions in body weight, systolic/diastolic BP, and Australian CVD risk score. • Evidence of a study wave (COVID-19 period) interaction for total carotenoids (p<0.001), suggesting pandemic-related modulation of dietary changes.

Providing AAC imaging results plus standardized education did not enhance FV intake beyond education alone over 12 weeks, as measured both objectively (plasma carotenoids) and by FFQ. Both groups, however, substantially increased FV intake and carotenoid levels, indicating that participation and the educational materials elicited meaningful dietary change (potential Hawthorne effect and trial participation effects). Despite null primary effects, the intervention improved lipid profiles (total cholesterol, non-HDL-c, LDL-c), maintained glucose relative to control, and modestly reduced estimated 5-year CVD risk, aligning with prior imaging-disclosure trials (CAC/carotid) showing improved risk factor control. Several factors may explain the lack of added dietary benefit from AAC result disclosure: conduct during COVID-19 with varying restrictions likely affected access and motivation for dietary changes; AAC is less widely recognized by clinicians than CAC, potentially attenuating downstream counseling/medication behaviors; unblinded design and withholding AAC in controls may have spurred behavior change in both groups; and nearly 42% of AAC+Ed participants had no AAC, which may have reassured rather than motivated change. Exploratory analyses suggest those with higher AAC burden derived greater cardiometabolic benefits (weight and BP reductions), indicating risk stratification may enhance responsiveness. The lipid improvements may reflect combined effects of small weight loss, dietary fat quality changes (higher fiber, lower saturated fat), and some medication initiation, though the study was not powered to disentangle mechanisms. Overall, imaging result disclosure may be a useful adjunct to standard education for improving certain CVD risk factors, even if short-term dietary intake changes are not superior to education alone.

In this 12-week randomized controlled trial of adults aged 60–80 years, providing individualized AAC imaging results alongside educational resources did not produce greater improvements in fruit and vegetable intake than education alone. Both groups meaningfully increased FV intake and plasma carotenoids. Disclosure of AAC results did, however, yield modest but significant improvements in lipid profiles and reduced estimated 5-year CVD risk versus controls. Larger, longer trials that target participants with confirmed AAC, integrate tailored behavior-change programs and clinician engagement, and include structured follow-up are warranted to determine mechanisms, optimize interventions, and assess sustained impacts on diet, physical activity, and CVD risk, particularly among those with higher AAC burden.

- Delivery of AAC results was virtual due to COVID-19, potentially limiting participants’ understanding. - Dietary assessment via FFQ over a 12-week recall window may introduce recall bias, portion size imprecision, incomplete food lists, and seasonal variation; the FFQ may be insensitive to small between-group differences despite detecting within-group changes. - Non-fasting blood samples collected at variable times likely increased biochemical variability, potentially underestimating differences (including carotenoids). - Target sample size (n=300) was not reached (n=227 completers), reducing power to detect the hypothesized effects on primary outcomes. - Unblinded participants and potential Hawthorne effect may have promoted behavior change in both groups, diminishing between-group contrasts. - COVID-19 restrictions and study wave effects influenced outcomes and may limit generalizability beyond pandemic conditions. - No adjustment for multiple comparisons (phase 2 effectiveness trial) increases risk of type I error among secondary outcomes. - Outcomes were not stratified by sex, limiting assessment of sex-specific effects.