Carbohydrate quality index and mortality risk in older adults at high cardiovascular risk

Abstract

Introduction: Carbohydrates are the global primary source of dietary energy, yet there is still controversy regarding the health effects of carbohydrate quality. We aimed to investigate the association of carbohydrate quality with all-cause and cause-specific mortality (cardiovascular disease [CVD], cancer, and other causes) in older adults at high CVD risk. Methods: Within the PREDIMED trial, an observational analysis was conducted involving 7,210 older adults (aged 55-80 years, 57.5% women). Carbohydrate quality variables were determined as cumulative averages from dietary information obtained annually from validated, semi-quantitative 137-item food frequency questionnaires. A carbohydrate quality index (CQI) was estimated as previously defined, by adding quintiles of four dimensions: glycemic index, total dietary fiber intake, whole-grain-to-total grain ratio, and solid carbohydrate-to-total carbohydrate ratio. CQI was the primary exposure variable, assessed both continuously and categorically by quintiles, comparing low intake (lowest quintile) vs. high intake (the four upper quintiles merged, as a reference category). Secondary exposures of interest were the individual carbohydrate quality dimensions. Mortality was assessed based on visit examinations, adjudications by the Clinical Event Committee, review of medical records and linkage to the National Death Index. Results: During a median follow-up of ~6 years, 425 deaths were documented (103 CVD, 169 cancer, and 153 other deaths). The mean (SD) cumulative average carbohydrate intake was 226.3 (53.5) g/d. Multivariable-adjusted hazard ratios (95% confidence intervals) showed every 1-point increase in cumulative average CQI score to be continuously associated with a 6% lower risk of cancer mortality 0.94 (0.89 to 0.99). Moreover, compared to participant with high intake, those with low cumulative average CQI intake presented a 28% higher risk of all-cause mortality 1.28 (1.03 to 1.59), and a 48% higher risk of cancer mortality 1.48 (1.04 to 2.10). Of the CQI dimensions, those relating to dietary fiber and whole grains appeared to drive the observed associations in this cohort. Conclusions: Low carbohydrate quality in diet was associated with all-cause and cancer mortality risk, with cancer mortality being the most affected in older adults. Further research is needed to explore additional aspects of carbohydrate quality and to examine these associations in diverse, large-scale populations.