A high dietary glycemic index increases total mortality in a Mediterranean population at high cardiovascular risk

PLoS One. 2014 Sep 24;9(9):e107968. doi: 10.1371/journal.pone.0107968. eCollection 2014.

Abstract

Objective: Different types of carbohydrates have diverse glycemic response, thus glycemic index (GI) and glycemic load (GL) are used to assess this variation. The impact of dietary GI and GL in all-cause mortality is unknown. The objective of this study was to estimate the association between dietary GI and GL and risk of all-cause mortality in the PREDIMED study.

Material and methods: The PREDIMED study is a randomized nutritional intervention trial for primary cardiovascular prevention based on community-dwelling men and women at high risk of cardiovascular disease. Dietary information was collected at baseline and yearly using a validated 137-item food frequency questionnaire (FFQ). We assigned GI values of each item by a 5-step methodology, using the International Tables of GI and GL Values. Deaths were ascertained through contact with families and general practitioners, review of medical records and consultation of the National Death Index. Cox regression models were used to estimate multivariable-adjusted hazard ratios (HR) and their 95% CI for mortality, according to quartiles of energy-adjusted dietary GI/GL. To assess repeated measures of exposure, we updated GI and GL intakes from the yearly FFQs and used Cox models with time-dependent exposures.

Results: We followed 3,583 non-diabetic subjects (4.7 years of follow-up, 123 deaths). As compared to participants in the lowest quartile of baseline dietary GI, those in the highest quartile showed an increased risk of all-cause mortality [HR = 2.15 (95% CI: 1.15-4.04); P for trend = 0.012]. In the repeated-measures analyses using as exposure the yearly updated information on GI, we observed a similar association. Dietary GL was associated with all-cause mortality only when subjects were younger than 75 years.

Conclusions: High dietary GI was positively associated with all-cause mortality in elderly population at high cardiovascular risk.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Age Factors
  • Aged
  • Aged, 80 and over
  • Cardiovascular Diseases / complications*
  • Cardiovascular Diseases / epidemiology*
  • Cardiovascular Diseases / metabolism
  • Cardiovascular Diseases / mortality
  • Cause of Death
  • Diet / adverse effects*
  • Dietary Carbohydrates / adverse effects
  • Feeding Behavior
  • Female
  • Glycemic Index*
  • Humans
  • Male
  • Middle Aged
  • Proportional Hazards Models
  • Risk Factors

Substances

  • Dietary Carbohydrates

Grant support

This report has been supported by the official funding agency for biomedical research of the Spanish government, Instituto de Salud Carlos III (ISCIII), through grants provided to research networks specifically developed for the trial [RTIC G03/140, to R E; RTIC RD 06/0045, to MA M-G] and through Centro de Investigación Biomédica en Red de Fisiopatología de la Obesidad y Nutrición (CIBERobn); Centro Nacional de Investigaciones Cardiovasculares [CNIC 06/2007]; Fondo de Investigación Sanitaria–Fondo Europeo de Desarrollo Regional [PI04-2239, PI 05/2584, CP06/00100, PI07/0240, PI07/1138, PI07/0954, PI 07/0473, PI10/01407, PI10/02658, PI11/01647, and P11/02505]; Ministerio de Ciencia e Innovación [AGL-2009-13906-C02 and AGL2010-22319-C03]; Fundación Mapfre 2010; Agencia Canaria de Investigación, Innovación y Sociedad de la Información-EU FEDER [PI 2007/050]; Consejería de Salud de la Junta de Andalucía [PI0105/2007]; Public Health Division of the Department of Health of the Autonomous Government of Catalonia; Generalitat Valenciana [ACOMP06109, GVACOMP2010-181, GVACOMP2011-151, CS2010-AP-111, and CS2011-AP-042]; Regional Government of Navarra [P27/2011] and IC-Q is supported by a scholarship of the Consejo Nacional de Ciencia y Tecnología de México (National Council on Science and Technology of México, CONACYT). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.