Purpose: Increasing vegetable intake and diversity are recommended to maintain better health. Evidence for the health benefits of vegetable diversity, separate from total intake, is scarce. We aimed to investigate the associations of vegetable diversity with subclinical measures of atherosclerosis and atherosclerotic vascular disease (ASVD) mortality.
Methods: Vegetable diversity was assessed within a validated food frequency questionnaire using a single question, 'How many different vegetables do you usually consume each day (< 1 to ≥ 6 per day)'. Cox proportional hazards modelling was used to examine the association between vegetable diversity and ASVD mortality in 1226 women aged ≥ 70 years without clinical ASVD or diabetes mellitus at baseline (1998). In 2001, B-mode ultrasonography was used to measure common carotid artery intima-media thickness (CCA-IMT) (n = 954) and carotid plaque severity (n = 968).
Results: Over 15 years (15,947 person-years) of follow-up, 238 ASVD-related deaths were recorded. For each additional different vegetable consumed per day, there was 17% lower hazard for ASVD mortality (HR = 0.83, 95% CI 0.78, 0.93, P = 0.001); a 1.7% lower mean CCA-IMT (B ± SE: - 0.013 ± 0.004, P < 0.001); and a 1.8% lower maximum CCA-IMT (B ± SE: - 0.017 ± 0.004, P < 0.001). Further adjustment for total vegetable intake attenuated the association between vegetable diversity and ASVD mortality (P = 0.114), but not CCA-IMT (P = 0.024). No association was observed between vegetable diversity and carotid plaque severity (P > 0.05).
Conclusions: Vegetable diversity may contribute to benefits in lowering risk of ASVD in older women. The reduction in risk is partly explained by increased total vegetable consumption.
Clinical trial registry: The Perth Longitudinal Study of Aging in Women (PLSAW) trial registration ID is ACTRN12617000640303. This study was retrospectively registered on the Australian New Zealand Clinical Trials Registry at http://www.anzctr.org.au.
Keywords: Atherosclerosis; Cardiovascular diseases; Diversity; Mortality; Older women; Vegetables.