Association of carbohydrate quality and all-cause mortality in the SUN Project: A prospective cohort study

Emerging evidence supports shifting the focus from carbohydrate quantity to carbohydrate quality to obtain greater health benefits. We investigated the association of carbohydrate quality with all-cause mortality using a single, multidimensional carbohydrate quality index (CQI) designed to account for multiple characteristics of carbohydrate quality.

A prospective study was conducted among 19,083 participants in the Seguimiento Universidad de Navarra (SUN) Project, a Mediterranean cohort of middle-aged university graduates. The CQI was based on four dimensions: high total dietary fiber intake, low glycemic index, high whole-grain carbohydrate: total grain carbohydrate ratio, and high solid carbohydrate: total carbohydrate ratio.

During 12.2 years of median follow-up, 440 deaths were identified. We found an inverse association between the CQI and all-cause mortality. The multivariable-adjusted hazard ratio (HR) for the highest vs. the lowest tertile of the CQI was 0.70 (95% CI, 0.53-0.93; P_trend = 0.018). However, each individual dimension of the CQI was not independently associated with lower mortality risk, with HR (95% CI) between extreme tertiles as follows: 0.77 (0.52-1.14; P_trend = 0.192) for high fiber intake; 0.81 (0.59-1.12; P_trend = 0.211) for low glycemic index; 0.87 (0.69-1.11; P_trend = 0.272) for high whole-grain carbohydrate: total-grain carbohydrate ratio; and 0.81 (0.61-1.07; P_trend = 0.139) for high solid carbohydrate: total carbohydrate ratio. Our analyses remained similar after using repeated measurements of diet with updated nutritional exposures after a ten-year follow-up.

The CQI as a whole, but none of its individual dimensions, was associated with lower mortality. The CQI seems to comprehensively capture the combined effects of quality domains.