Coronary Heart Disease and Dietary Carbohydrate, Glycemic Index, and Glycemic Load: Dose-Response Meta-analyses of Prospective Cohort Studies

Abstract

ObjectiveTo clarify the role of dietary carbohydrate, glycemic index (GI), and glycemic load (GL) in progression from health to coronary heart disease (CHD) by determining disease-nutrient risk relation (RR) values needed for intake ranges within jurisdictions and across the globe.MethodsWe performed a literature search of MEDLINE and EMBASE for prospective cohort studies that used truly valid dietary instruments in heathy adults published from January 1, 2000, to June 5, 2018. Relevant observations were extracted by 2 reviewers independently. We used dose-response meta-analysis accounting for nonindependence of results within studies. Bradford-Hill criteria were used to assess causality.ResultsEligible studies had a mean follow-up of 11 years (range, 5-19 years), were conducted in North America, Europe, and East Asia, and yielded combined RRs of 1.44 (95% CI, 1.25-1.65) per 65 g/d GL (11 studies) and 1.24 (95% CI, 1.12-1.38) per 10 U GI (10 studies) (glucose scale). The CHD-carbohydrate RR on GI was 1.66 (95% CI, 1.23-2.25) per 98 g/d of carbohydrates per 10 units GI. The 65 g/d GL, 10 U GI, and 98 g/d carbohydrate values corresponded to oral intakes from the 10th to the 90th percentiles within sampled populations. Inconsistencies were minor (I2≤20%), as were small-study effects (P=.61 for GL and P=.26 for GI). Funnel plots were symmetric. Cubic spline dose-response meta-analysis yielded RRs as follows: across the global range for GL (55-290 g/d), 5.5 (95% CI, 3.1-9.8) (I2=0); for GI (47-82 U), 2.71 (95% CI, 1.47-4.40) (I2=0); and for the CHD-carbohydrate dependence on GI (50-80 U), 4.57 (95% CI, 1.86-11.4) (I2=16%). Bradford-Hill criteria indicated that these relations were probably causal.ConclusionStrong and probably causal CHD-GL and GI RRs exist within populations. The RRs were remarkably higher across global exposures. The results support the consideration of these markers of carbohydrate food quality in dietary guidelines for general populations.Trial RegistrationPROSPERO Identifier: CRD42013004504

Dietary Glycemic Index and Load and the Risk of Type 2 Diabetes: A Systematic Review and Updated Meta-Analyses of Prospective Cohort Studies

“…Further, only one meta-analysis [9] restricted their study selection to those applying truly valid dietary instruments, which were for nutrient amounts in general (validity correlation > 0.5) [18]. For GI and GL, a validity correlation for carbohydrate > 0.55 is considered appropriate when assessing coronary heart disease and GI and GL risk relations [19], and was applied here. This higher value (0.55) was selected based on the study of Brunner et al [18], who recommended, in general, a value of 0.5 for nutrients, which was adopted by Barclay et al in 2008 [9] in their studies of T2D GI and GL risk ratios, to which 10% was added to allow for any error of the estimation.…”

“…Therefore, we updated the meta-analyses (as in [9]) for both GI and GL, again using studies with truly valid dietary instruments. A difference is that we defined a truly valid dietary instrument as one that has a validity correlation > 0.55 for carbohydrates [19] rather than 0.5 for nutrients in general. A further difference is that we used preferred quantitative dose–response meta-analysis (DRM) [5,19,20,21].…”

“…Dose response meta-analysis (DRM) is preferred to extreme quantile meta-analysis (EQM) because it uses more of the available data and allows an assessment of the risk ratios or risk relations (RR) per unit increment of exposure, which is particularly helpful when undertaking global DRM (i.e., increments in RR across all levels of exposure from lowest to highest exposures worldwide) and when looking for potential nonlinear associations in the dose-response over the global range [5,13,19]. A drawback is that the use of dietary instruments that do not collect representative information leads to an overdispersion of the range of intake estimates, which has a major consequence—an underestimation of the dose-response relationships, suggested to be up to a 75% reduction [22].…”

Destigmatizing Carbohydrate with Food Labeling: The Use of Non-Mandatory Labelling to Highlight Quality Carbohydrate Foods

“…In a recent systemic review and meta-analysis of prospective cohorts, Reynolds et al [ 16 ] concluded that, compared with dietary fibre and whole grains, the GI might not be as useful a measure of carbohydrate quality for the prevention of chronic disease. Conversely, subsequent dose–response meta-analyses of prospective cohorts showed that the risk of coronary heart disease and type 2 diabetes increased by 24% and 27% per 10 unit increase in GI, respectively [ 97 , 98 ]. Food Standards Australia New Zealand permits “low,” “medium,” and “high” GI claims.…”

Growing Up Fast!

“…The most frequently accessed article on our website (www. mcpiqojournal.org) was a case report on unusual presentations of vitamin B 12 deficiency 12 (6,060 requests), followed by an article on the relationship between dog ownership and cardiovascular health 13 (3,195) and a dose-response meta-analysis of coronary heart disease and dietary carbohydrates 14 (590). The most frequently accessed articles on ScienceDirect.com addressed worksite wellness intervention 15 (729 requests), cost comparison of different approaches to sedation during gastrointestinal endoscopy, 16 (455) and a case report on immunemediated cerebellitis with immune checkpoint inhibitor therapy (410).…”