Impact of lunch with carbohydrates differing in glycemic index on children's cognitive functioning in the late postprandial phase: a randomized crossover study

Purpose Studies about effects of lunch dietary Glycemic Index (GI) on cognition of schoolchildren are scarce. Our previous CogniDo GI study found no changes of cognition in the early postprandial phase after consumption of two rice types with medium vs. high dietary GI for lunch (i.e., 45 min after starting lunch). This study investigated whether the dietary GI of lunch has an impact on cognition of schoolchildren in the late postprandial phase, 90 min after lunch. Methods A randomized, 2 × 2 crossover intervention study was conducted at a comprehensive school with 5th and 6th grade students. Participants (n = 212) were randomly assigned to either sequence 1 or 2. In the first period, participants of sequence 1 received a dish with high GI rice (GI: 79), those of sequence 2 with medium GI rice (GI: 64)—in the second period, 1 week later, vice versa. Computer-based cognitive testing was performed 90 min after lunch examining tonic alertness, visual search and task switching, and working memory. Treatment effects and treatment effects adjusted for estimated lunch glycemic load (GL) were analyzed using a linear mixed model. Results The selected cognitive parameters were not affected by the GI of lunch 90 min after lunch, neither after intention-to-treat nor in the per-protocol analysis. Adjustment for GL also did not change results. Conclusion The present study revealed no notable differences after the consumption of two rice types with medium vs. high dietary GI for lunch in children’s cognitive function in the late postprandial phase, 90 min after lunch. Clinical trial registration German Clinical Trials Register (DRKS00013597); date of registration: 16/04/2018, retrospectively registered.

Dietary glycemic index and glycemic load in relation to risk of breast cancer

Objective: Previous studies on the association between glycemic index (GI) and load (GL) in relation to breast cancer risk are contradictory. The aim of this study was to examine the association between dietary GI and GL and risk of breast cancer in Iranian women. Design: Population-based case-control. Dietary GI and GL were assessed using a validated Willett-format 106-item semi-quantitative food frequency questionnaire. Setting: Isfahan, Iran. Participants: Cases were 350 patients with newly diagnosed stage I-IV breast cancer, for whom the status of breast cancer was confirmed by physical examination and mammography. Controls were 700 age-matched apparently healthy individuals who were randomly selected from general population. Results: After controlling for potential confounders, individuals in the highest tertile of dietary GI had 47% higher odds of breast cancer than women in the lowest tertile (OR: 1.47; 95% CI: 1.02-2.12). Stratified analysis by menopausal status showed such association among postmenopausal women (OR: 1.51; 95% CI: 1.02-2.23). We found no significant association between dietary GL and odds of breast cancer either before (OR: 1.35; 95% CI: 0.99-1.84) or after adjustment for potential confounders (OR: 1.24; 95% CI: 0.86-1.79). In addition, stratified analysis by menopausal status revealed no significant association between dietary GL and odds of breast cancer. Conclusions: Our findings showed a significant positive association between dietary GI and odds of breast cancer. However, we observed no significant association between dietary GL and odds of breast cancer.

Associations of dietary glycemic index and load during pregnancy with blood pressure, placental hemodynamic parameters and the risk of gestational hypertensive disorders

Purpose The aim of this study was to examine the associations of dietary glycemic index and load with gestational blood pressure, placental hemodynamic parameters and the risk of gestational hypertensive disorders. Methods In a population-based cohort among 3378 pregnant Dutch women, dietary glycemic index and load were assessed from food frequency questionnaires at median 13.4 (95% range 9.9–22.9) weeks gestation. Blood pressure was measured in early-, mid- and late-pregnancy. Placental hemodynamic parameters were measured in mid- and late-pregnancy by ultrasound. Data on gestational hypertensive disorders was acquired from medical records. Results Mean dietary glycemic index (SD) was 58 (3) and mean dietary glycemic load (SD) was 155 (47). Dietary glycemic index was not associated with blood pressure, placental hemodynamic parameters and the risk of gestational hypertensive disorders. Higher dietary glycemic load SDS was associated with a higher diastolic blood pressure in early-pregnancy, remaining after adjustment for socio-demographic and lifestyle factors ((0.98 (95% CI 0.35–1.61) mmHg per SDS increase in glycemic load). No other associations of glycemic load with blood pressure or placental hemodynamic parameters and the risk of gestational hypertensive disorders were present. No significant associations of dietary glycemic index and load quartiles with longitudinal blood pressure patterns from early to late-pregnancy were present. Conclusion Within this low-risk pregnant population, we did not find consistent associations of dietary glycemic index and load with blood pressure, placental hemodynamic parameters and the risk of gestational hypertensive disorders. Further studies need to assess whether the effects on gestational hemodynamic adaptations are more pronounced among high-risk women with an impaired glucose metabolism.

Dose-Dependent Associations of Dietary Glycemic Index, Glycemic Load, and Fiber With 3-Year Weight Loss Maintenance and Glycemic Status in a High-Risk Population: A Secondary Analysis of the Diabetes Prevention Study PREVIEW

<a>OBJECTIVE</a> <p>To <a></a><a>examine longitudinal and dose-dependent associations of dietary glycemic index (GI), glycemic load (GL), and fiber with body weight and glycemic status during 3-year weight-loss maintenance (WLM)</a> in high-risk adults.</p> <p>RESEARCH DESIGN AND METHODS</p> <p>This secondary analysis used pooled data from the PREVIEW randomized controlled trial, which was designed to test the effects of four diet and physical activity interventions. 1,279 participants with overweight or obesity (aged 25–70 years; BMI≥25 kg·m^-2) and pre-diabetes at baseline were included. <a>Multi-adjusted linear mixed models </a><a>with repeated measurements</a> were used to assess longitudinal and dose-dependent associations, by merging the participants into one group and dividing them into <a></a><a>GI, GL, and fiber </a>tertiles, respectively. </p> <p>RESULTS</p> <p>In the available-case and complete-case analyses, each 10-unitincrement in GI was associated with a greater regain of weight (0.46 kg·year^-1; 95% CI 0.23, 0.68; <i>P</i><0.001) and increase in HbA_1c. Each 20-unit increment in GL was associated with a greater regain of weight (0.49 kg·year^-1; 0.24, 0.75; <i>P</i><0.001) and increase in HbA_1c. The associations of GI and GL with HbA_1c were independent of weight change. Compared with those in the lowest tertiles, participants in the highest GI and GL tertiles had significantly higher weight regain and increases in HbA_1c. Fiber was inversely associated with increases in waist circumference, but the associations with weight regain and glycemic status did not remain robust in different analyses.</p> <p>CONCLUSIONS</p> <p>Dietary GI and GL were positively associated with weight regain and deteriorating glycemic status. Stronger evidence on the role of fiber is needed.</p>