Dietary Glycemic Index and Load and the Risk of Type 2 Diabetes: Assessment of Causal Relations.

While dietary factors are important modifiable risk factors for type 2 diabetes (T2D), the causal role of carbohydrate quality in nutrition remains controversial. Dietary glycemic index (GI) and glycemic load (GL) have been examined in relation to the risk of T2D in multiple prospective cohort studies. Previous meta-analyses indicate significant relations but consideration of causality has been minimal. Here, the results of our recent meta-analyses of prospective cohort studies of 4 to 26-y follow-up are interpreted in the context of the nine Bradford-Hill criteria for causality, that is: (1) Strength of Association, (2) Consistency, (3) Specificity, (4) Temporality, (5) Biological Gradient, (6) Plausibility, (7) Experimental evidence, (8) Analogy, and (9) Coherence. These criteria necessitated referral to a body of literature wider than prospective cohort studies alone, especially in criteria 6 to 9. In this analysis, all nine of the Hill's criteria were met for GI and GL indicating that we can be confident of a role for GI and GL as causal factors contributing to incident T2D. In addition, neither dietary fiber nor cereal fiber nor wholegrain were found to be reliable or effective surrogate measures of GI or GL. Finally, our cost-benefit analysis suggests food and nutrition advice favors lower GI or GL and would produce significant potential cost savings in national healthcare budgets. The high confidence in causal associations for incident T2D is sufficient to consider inclusion of GI and GL in food and nutrient-based recommendations.

Dietary (Poly)phenols, Brown Adipose Tissue Activation, and Energy Expenditure: A Narrative Review.

The incidence of overweight and obesity has reached epidemic proportions, making the control of body weight and its complications a primary health problem. Diet has long played a first-line role in preventing and managing obesity. However, beyond the obvious strategy of restricting caloric intake, growing evidence supports the specific antiobesity effects of some food-derived components, particularly (poly)phenolic compounds. The relatively new rediscovery of active brown adipose tissue in adult humans has generated interest in this tissue as a novel and viable target for stimulating energy expenditure and controlling body weight by promoting energy dissipation. This review critically discusses the evidence supporting the concept that the antiobesity effects ascribed to (poly)phenols might be dependent on their capacity to promote energy dissipation by activating brown adipose tissue. Although discrepancies exist in the literature, most in vivo studies with rodents strongly support the role of some (poly)phenol classes, particularly flavan-3-ols and resveratrol, in promoting energy expenditure. Some human data currently are available and most are consistent with studies in rodents. Further investigation of effects in humans is warranted.

Perspective: Improving Nutritional Guidelines for Sustainable Health Policies: Current Status and Perspectives.

A large body of evidence supports the notion that incorrect or insufficient nutrition contributes to disease development. A pivotal goal is thus to understand what exactly is appropriate and what is inappropriate in food ingestion and the consequent nutritional status and health. The effective application of these concepts requires the translation of scientific information into practical approaches that have a tangible and measurable impact at both individual and population levels. The agenda for the future is expected to support available methodology in nutrition research to personalize guideline recommendations, properly grading the quality of the available evidence, promoting adherence to the well-established evidence hierarchy in nutrition, and enhancing strategies for appropriate vetting and transparent reporting that will solidify the recommendations for health promotion. The final goal is to build a constructive coalition among scientists, policy makers, and communication professionals for sustainable health and nutritional policies. Currently, a strong rationale and available data support a personalized dietary approach according to personal variables, including sex and age, circulating metabolic biomarkers, food quality and intake frequency, lifestyle variables such as physical activity, and environmental variables including one's microbiome profile. There is a strong and urgent need to develop a successful commitment among all the stakeholders to define novel and sustainable approaches toward the management of the health value of nutrition at individual and population levels. Moving forward requires adherence to well-established principles of evidence evaluation as well as identification of effective tools to obtain better quality evidence. Much remains to be done in the near future.

Giocampus school: a "learning through playing" approach to deliver nutritional education to children.

To improve nutritional knowledge of children, single-group educational interventions with pre/post knowledge assessment were performed in primary schools in Parma, Italy, participating to the Giocampus Program. A total of 8165 children (8-11 years old) of 3rd, 4th and 5th grades of primary school were involved in 3 hours per class nutritional lessons, with specifically designed games and activities for each school grade. To evaluate children learning, a questionnaire was administered before and after three months of educational intervention. A total of 16330 questionnaires were analysed. Children nutritional knowledge significantly increased (p< 0.001) in all school grades. The integrated "learning through playing" approach, including the educational figures, tools and games, was successful in improving children's nutritional knowledge. A stable integration of this method in primary school settings could prepare a new generation of citizens, better educated on health-promotion lifestyles.

Development and validation of a food frequency questionnaire for the assessment of dietary total antioxidant capacity.

The total antioxidant capacity (TAC) of the diet may be an important tool to monitor the protective effect of plant foods in epidemiological studies. We developed a semi-quantitative FFQ for the assessment of dietary TAC by 3 different assays, i.e., Trolox equivalent antioxidant capacity (TEAC), total radical-trapping antioxidant parameter (TRAP) and ferric reducing-antioxidant power (FRAP). The FFQ consists of 53 questions about the major sources of dietary TAC in Northern Italy and was validated against a 3-d weighed food record (3D-WR) in 285 individuals (159 males and 126 females) aged 35-88 y and living in the province of Parma (Italy). Plasma TAC was also evaluated in a subgroup of subjects using the TEAC and FRAP assays. The FFQ was associated with 3D-WR (quadratic-weighted kappa = 0.49 for TEAC, 0.53 for TRAP, and 0.49 for FRAP; P < 0.0001) and proved reasonably accurate to classify individuals into quartiles of TAC intake. The FFQ had a good repeatability when readministered after 1 y in 55 subjects (quadratic-weighted kappa for intertertile agreement = 0.66 for TEAC, 0.70 for TRAP and 0.68 for FRAP; P < 0.0001). With both dietary instruments, the main contributors to TAC intake were coffee and tea in women and alcoholic beverages in men, followed by fruits and vegetables in both sexes. Plasma TAC and dietary TAC were not associated. In conclusion, our FFQ has the potential for being used to rank subjects on the basis of their antioxidant intake as determined by dietary TAC in large epidemiological studies. The FFQ should be validated in external populations before being used for research purposes.

PASSCLAIM--body weight regulation, insulin sensitivity and diabetes risk.

BACKGROUND: Insulin sensitivity is a key function in human metabolism because it has a crucial role in the development of disease that are increasingly common in modern society. Impaired insulin sensitivity is an important determinant of type 2 diabetes; moreover, it has been proposed as an independent risk factor for cardiovascular disease. Thus, reduced insulin sensitivity is strongly associated with the metabolic syndrome, which represents a cluster of metabolic abnormalities and cardiovascular risk factor. Insulin sensitivity can be modulated by different environmental factors, including dietary habits. Obesity, especially if associated with abdominal adiposity, impairs insulin-sensitivity while physical activity can improve it; however, the composition of the habitual diet is clearly an important regulator of this function. AIM: To evaluate methodologies and markers that can be used to substantiate existing and potential claims of beneficial effects of foods on relevant functions connected with body fat deposition, insulin sensitivity and blood glucose regulation. RESULTS: We have reviewed the scientific basis for existing and potential claims, based not only on modifications of the target functions (body fat deposition, insulin sensitivity and blood glucose regulation) but also on modifications of other relevant associated functions (energy intake, energy expenditure, fat storage and oxidation, lipotoxicity, body fat composition, inflammation, oxidative stress, vascular function, glucose production and utilization). In this context we have identified a number of markers and evaluated appropriate method to measure and validate them. CONCLUSIONS: Relevant functions contributing to overweight, the metabolic syndrome and diabetes have been identified. The evidence reviewed indicates that in this field the link between nutrition, biological responses and diseases is clearly established. Therefore, there is a strong potential to develop functional food science. The major gap in the evidence continues to be the lack of diet based intervention trials of sufficient duration to be relevant for affecting the natural history of these conditions.