Fruit, vegetable, and legume consumption and cardiovascular disease and mortality in an international population

Abstract

Background: Diet is an important modifiable risk factor for cardiovascular disease. Numerous studies have examined the association between dietary intake and cardiovascular disease in North America and Europe, but little information is available on potential associations in many geographic regions including South Asia, South America, Africa, China, and the Middle East. Presently, it is unclear whether the findings from Western countries are applicable to these regions where population characteristics, background diet, and disease risk differ. This thesis aims to investigate the relationship between diet and cardiovascular disease and mortality in a heterogeneous, international population. Methods: Baseline data from the Prospective Urban Rural Epidemiology (PURE) study was used to investigate the availability, affordability, and consumption of fruits and vegetables. Additionally, PURE baseline and follow-up was used to examine the association between foods (fruits, vegetables and legumes) and macronutrients (total and fat subtypes, carbohydrate and protein) and cardiovascular outcomes and mortality. PURE is a prospective cohort study in individuals aged 35 to 70 years in 18 high-income middle-income and low-income countries on five continents. Availability and affordability of fruits and vegetables was collected from centrally located grocery stores and market places in each PURE community. Diet was measured using country and region-specific food frequency questionnaires at baseline. Case-report forms, death certificates, medical records and verbal autopsies were used to capture data about major cardiovascular events, and death during follow-up. The cost and diversity of fruits and vegetables was documented and mean fruit and vegetable intake by their relative cost was assessed. Associations between fruit, vegetable and legume consumption with risk of cardiovascular outcomes and mortality were examined. We investigated the association between macronutrients and risk of mortality and modeled nutrient replacement using energy-adjustment and joint effect models. Results: Results from the PURE study indicate that consumption of fruits and vegetables is low worldwide, particularly in low-income countries, and this is associated with low affordability. Higher fruit, vegetable and legume consumption was associated with a lower risk of non-cardiovascular, and total mortality and benefits appear to be maximal at three to four servings per day. This finding indicates that health benefits can be achieved at intake lower than most dietary recommendations, an approach that is likely to be more affordable in poor countries. Higher carbohydrate intake was positively associated with an increased risk of mortality, while total and fat subtypes, and protein was inversely associated with death. For the nutrient replacement analysis, the joint effect method demonstrated higher agreement with the single nutrient results compared to the conventional energy-adjustment method. This result suggests that traditional nutrient replacement modeling is not appropriate for international populations with diverse nutrient intake. Conclusions: Dietary intake varies across geographic regions and interventions to improve diet and nutrition recommendations should be tailored to the geographic setting.