A systematic review of educational nutrition interventions based on behavioral theories in school adolescents.

The purpose of this study was to summarize the evidence from studies conducted on adolescents, evaluating educational nutrition interventions for the modification of food consumption through controlled trials based on behavior change theories or models and implemented in school settings. A systematic search was carried out through PubMed and ERIC databases between November and December 2020, and updated in February 2023; English-language keywords were used, and no publication date limits were applied. Two authors independently performed the search, data extraction, data synthesis and risk of bias assessment. Twelve studies meeting the inclusion criteria were included. The interventions were based on different theories; the most used was the Social Cognitive Theory. Eleven of the twelve studies showed favorable modifications in the consumption of at least two of the food groups. Most studies were at low risk of bias, and only one was classified as high risk. It is concluded that educational nutrition interventions based on behavior change theories/models and implemented in the school setting influence positive changes in adolescents eating behavior.

Effect of flaxseed (Linum usitatissimum) supplementation on glycemic control and insulin resistance in prediabetes and type 2 diabetes: A systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: Prediabetes and type 2 Diabetes Mellitus (T2DM) are characterized by increased blood sugar concentration and insulin resistance. Although there are only a few reports of potential benefits of flaxseed's consumption on different metabolic parameters, there is no evidence of its effect among people with these conditions. OBJECTIVES: The present systematic review and meta-analysis aimed to assess the effect of flaxseed supplementation on glycemic control variables and insulin resistance in prediabetes and T2DM. METHODS: A literature search was conducted through PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), and Web of Science, to identify Randomized Control Trials (RCTs) that evaluated the effect of milled or ground flaxseed supplementation on fasting blood glucose, HbA1c, insulin concentrations, or HOMA-IR. The data were analyzed using Comprehensive Meta-Analysis (CMA) software version 3.3 in a fixed-effect model. RESULTS: Seven studies were included in the systematic review and the meta-analysis, the results showed a significant reduction on fasting blood sugar (SMD: -0.392, 95% CI: -0.596, -0.187, p = <0.001, I2 = 64.81%) insulin concentrations, (SMD: -0.287, 95% CI: -0.534, -0.041, p = 0.022, I2 = 32.53%), HbA1c (SMD: -0.442, 95% CI: -0.770, -0.114, p = 0.008, I2 = 11.058%), and HOMA-IR (SMD: -0.284, 95% CI: -0.530, -0.038, p = 0.024, I2 = 0.00%) after flaxseed supplementation. CONCLUSIONS: Flaxseed supplementation seems to improve glycemic control variables and insulin resistance in prediabetes and T2DM; however, more RCTs are needed to have more decisive evidence about doses, method of supplementation, and the possible effect of synergy with the dietetic treatment.