Dietary glycemic index, glycemic load, and cause-specific mortality: two population-based prospective cohort studies

Overall glycaemic index and dietary glycaemic load and all-cause and cause-specific mortality in women from the Mexican Teachers' Cohort

Previous studies have found direct associations between glycaemic index (GI) and glycaemic load (GL) with chronic diseases. However, this evidence has not been consistent in relation to mortality, and most data regarding this association come from high-income and low-carbohydrate-intake populations. The aim of this study was to evaluate the association between the overall GI and dietary GL and all-cause mortality, CVD and breast cancer mortality in Mexico. Participants from the Mexican Teachers' Cohort (MTC) study in 2006-2008 were followed for a median of 10 years. Overall GI and dietary GL were calculated from a validated FFQ. Deaths were identified by the cross-linkage of MTC participants with two national mortality registries. Cox proportional hazard models were used to estimate the impact of GI and GL on mortality. We identified 1198 deaths. Comparing the lowest and highest quintile, dietary GI and GL appeared to be marginally associated with all-cause mortality; GI, 1·12 (95 % CI: 0·93, 1·35); GL, 1·12 (95 % CI: 0·87, 1·44). Higher GI and GL were associated with increased risk of CVD mortality, GI, 1·30 (95 % CI: 0·82, 2·08); GL, 1·64 (95 % CI: 0·87, 3·07) and with greater risk of breast cancer mortality; GI, 2·13 (95 % CI: 1·12, 4·06); GL, 2·43 (95 % CI: 0·90, 6·59). It is necessary to continue the improvement of carbohydrate quality indicators to better guide consumer choices and to lead the Mexican population to limit excessive intake of low-quality carbohydrate foods.

Perspective on the health value of carbohydrate-rich foods: glycemic index and load; fiber and whole grains

BACKGROUND

For over 45 y increasingly comprehensive food tables of glycemic index (GI) and glycemic load (GL) have been published in the American Journal of Clinical Nutrition to determine the GI and GL values of diets. Recently the WHO based on a 2019 series of meta-analyses concluded that increases in dietary fiber and whole grains but not reduction in GI or GL warranted recommendations for chronic disease reduction.

METHODS AND RESULTS

We therefore provide a perspective on the current evidence that indicates that GI and GL are also determinants of risk of chronic disease outcomes. We are also concerned with the term dietary fiber used in the singular when there are many dietary fibers that may differ in their physiological effects. Furthermore, the term "whole grains" that refers to "whole grain flour" limits the exploration of "intact" grains that are low GI and have useful physiological effects.

CONCLUSION

We conclude that all these determinants of the health values of carbohydrate-rich foods should be used in combination to assess the health value of carbohydrate-rich foods.

Are dietary factors associated with cardiometabolic risk factors in patients with non-alcoholic fatty liver disease?

Background

Non-alcoholic fatty liver disease (NAFLD) is intricately linked with dietary patterns and metabolic homeostasis. Therefore, the present study focused to investigate the relation between dietary patterns and cardiometabolic risk factors related to fatty liver in NAFLD patients.

Methods

This cross-sectional study included 117 individuals whose body mass index (BMI) threshold of 25 or above diagnosed with NAFLD by magnetic resonance imaging. The hospital database was used to review the patients' medical records such as lipid parameters, and fasting blood sugar. Anthropometric measurements and body composition were measured by researchers. Likewise, data from 24-h dietary recalls of individuals were collected to analyze their energy and nutrient intakes besides calculating dietary insulin index (DII), dietary insulin load (DIL), dietary glycemic index (DGI), and dietary glycemic load (DGL).

Results

Participants consuming diets with distinct levels of DII, DIL, DGI, and DGL exhibited variations in dietary energy and nutrient intake. Specifically, differences were noted in carbohydrate intake across quartiles of DII, DIL, DGI, and DGL, while fructose consumption showed variability in DGL quartiles (p ≤ 0.05). Moreover, sucrose intake demonstrated distinctions in both DII and DGL quartiles (p ≤ 0.05). No statistical difference was found in biochemical parameters and the fatty liver index among different levels of DII, DIL, DGI, and DGL (p > 0.05). After adjusting for potential confounders, participants with a higher DGI had four times greater odds of developing metabolic syndrome compared to those in the bottom quartile (OR, 4.32; 95% CI [1.42-13.11]).

Conclusion

This study provides initial evidence of the intricate association between dietary factors and NAFLD, emphasizing the necessity for further research including prospective designs with larger sample sizes, to garner additional insights.

Association of glycaemic index and glycaemic load with type 2 diabetes, cardiovascular disease, cancer, and all-cause mortality: a meta-analysis of mega cohorts of more than 100 000 participants

BACKGROUND

There is debate over whether the glycaemic index of foods relates to chronic disease. We aimed to assess the associations between glycaemic index (GI) and glycaemic load (GL) and type 2 diabetes, cardiovascular disease, diabetes-related cancers, and all-cause mortality.

METHODS

We did a meta-analysis of large cohorts (≥100 000 participants) identified from the Richard Doll Consortium. We searched the Cochrane Library, MEDLINE, PubMed, Embase, Web of Science, and Scopus for cohorts that prospectively examined associations between GI or GL and chronic disease outcomes published from database inception to Aug 4, 2023. Full-article review and extraction of summary estimates data were conducted by three independent reviewers. Primary outcomes were incident type 2 diabetes, total cardiovascular disease (including mortality), diabetes-related cancers (ie, bladder, breast, colorectal, endometrial, hepatic, pancreatic, and non-Hodgkin lymphoma), and all-cause mortality. We assessed comparisons between the lowest and highest quantiles of GI and GL, adjusting for dietary factors, and pooling their most adjusted relative risk (RR) estimates using a fixed-effects model. We also assessed associations between diets high in fibre and whole grains and the four main outcomes. The study protocol is registered with PROSPERO, CRD42023394689.

FINDINGS

From ten prospective large cohorts (six from the USA, one from Europe, two from Asia, and one international), we identified a total of 48 studies reporting associations between GI or GL and the outcomes of interest: 34 (71%) on various cancers, nine (19%) on cardiovascular disease, five (10%) on type 2 diabetes, and three (6%) on all-cause mortality. Consumption of high GI foods was associated with an increased incidence of type 2 diabetes (RR 1·27 [95% CI 1·21-1·34]; p<0·0001), total cardiovascular disease (1·15 [1·11-1·19]; p<0·0001), diabetes-related cancer (1·05 [1·02-1·08]; p=0·0010), and all-cause mortality (1·08 [1·05-1·12]; p<0·0001). Similar associations were seen between high GL and diabetes (RR 1·15 [95% CI 1·09-1·21]; p<0·0001) and total cardiovascular disease (1·15 [1·10-1·20]; p<0·0001). Associations between diets high in fibre and whole grains and the four main outcomes were similar to those for low GI diets.

INTERPRETATION

Dietary recommendations to reduce GI and GL could have effects on health outcomes that are similar to outcomes of recommendations to increase intake of fibre and whole grain.

FUNDING

Banting and Best and the Karuna Foundation.

Dietary glycemic index, glycemic load and all-cause and cause-specific mortality: A meta-analysis of prospective cohort studies

BACKGROUND & AIMS

The findings of previous studies investigating the association between dietary glycemic index, glycemic load, and the risk of mortality have been inconsistent. We performed a meta-analysis to evaluate this association.

METHODS

A systematic search in PubMed and Web of Science databases was conducted to identify prospective cohort studies on dietary glycemic index and load with risk of mortality through January 2023. Study-specific relative risks (RR) were combined by using random effects models.

RESULTS

Fifteen prospective cohort studies with a total of 527,650 participants and 48,598 all-cause and cause-specific deaths were included in the current meta-analysis. Pooled analyses indicated a higher risk of all-cause mortality (RR = 1.10, 95% CI: 1.00-1.20) and stroke mortality (RR = 1.30, 95% CI: 1.04-1.62) for the highest versus lowest levels of glycemic index. A significant non-linear association was found between glycemic index and mortality of all-causes (P for non-linearity = 0.02) and CVD (P for non-linearity <0.001), indicating increased risk at high levels of glycemic index (≥63.1 for all-cause mortality; ≥72.8 for CVD mortality). Glycemic load was positively associated with risk of CVD mortality (RR = 1.18, 95% CI: 1.09-1.27) and stroke mortality (RR = 1.30, 95% CI: 1.05-1.60) in the highest versus lowest meta-analysis. For cancer mortality, there was no significant association with glycemic index, but the association with glycemic load differed by sex.

CONCLUSIONS

Our results indicated that high glycemic index and glycemic load was associated with an increased risk of mortality from CVD and stroke. Further large prospective studies are warranted to provide definitive evidence in subgroups.

Dietary glycemic index, glycemic load, and renal cancer risk: findings from prostate, lung, colorectal, and ovarian cancer trial

Background

Dietary glycemic index (GI) or glycemic load (GL) has been associated with the development of many cancers, but the evidence for renal cancer is still limited. The aim of the present study was to investigate the association between GI or GL and renal cancer risk in the Prostate, Lung, Colorectal, and Ovarian Cancer (PLCO) Screening Trial.

Methods

The cohort for our analysis consisted of 101,190 participants. GI and GL were calculated from the FFQ data using previously published reference values. Multivariate-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox regression model after adjusting for most known renal cancer risk factors.

Results

During a median of 12.2 years of follow-up, 443 incident renal cancer cases occurred. Higher dietary GI was significantly associated with a higher risk of renal cancer (HR_Q3vsQ1: 1.38; 95% CI: 1.09-1.74; p for trend = 0.008). There was no significant association between dietary GL and renal cancer risk (HR_Q3vsQ1 = 1.12, 95% CI = 0.79-1.59, p for trend = 0.591). Spline regression plot revealed a higher risk of renal cancer with a higher GI but not GL. There was no statistical evidence for nonlinearity (p for nonlinearity >0.05).

Conclusion

In summary, findings of this large-scale prospective cohort study suggested that dietary GI may be associated with the risk of renal cancer. If confirmed in other populations and settings, dietary GI could be considered as a modifiable risk factor for renal cancer prevention.