Validation Of Estimated Glycaemic Index And Glycaemic Load, Stratified By Race, In The Adventist Health Study-2 (Ahs-2)

Objective: Few studies have validated FFQ estimates of dietary glycaemic index (GI) and load (GL). We investigated how well our estimates of overall GI and GL from FFQs correlate with estimates from repeated 24 h recall data to validate overall GI and GL in the Adventist Health Study-2 (AHS-2). Design: The AHS-2 is a prospective population-based cohort of 95 873 Seventh-day Adventist adult church members enrolled from 2002 to 2007 to investigate diet, cancer and mortality. Setting: A 204-item FFQ was used to assess race- and gender-specific validity of GI and GL and 24 h recall data, from the calibration sub-study, were used as the reference. Participants: The 734 calibration study participants were randomly selected by church and included approximately equal numbers of blacks and whites but were otherwise similar to the whole cohort with respect to gender, age, education and vegetarian status. Results: The deattenuated correlation coefficients for overall GI ranged from 0 center dot 19 (95 % CI -0 center dot 06, 0 center dot 53) in black men to 0 center dot 46 (95 % CI 0 center dot 40, 0 center dot 60) in black women, with both non-black men and women falling between those values (0 center dot 45 (95 % CI 0 center dot 35, 0 center dot 65) and 0 center dot 38 (95 % CI 0 center dot 27, 0 center dot 57), respectively). GL correlations were somewhat higher for all study participants. When looking at the entire cohort, the deattenuated validity correlation value for overall GI was (r 0 center dot 38, 95 % CI 0 center dot 36, 0 center dot 47) and GL was (r 0 center dot 39, 95 % CI 0 center dot 34, 0 center dot 49). Conclusions: Our findings support the cautious use of our FFQ in epidemiological studies when assessing associations of overall GI and GL with disease risk. However, observed differences by race should be considered when interpreting results.