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Multiple factors may affect the metabolic fate of carbohydrates. Today, well-standardised and accepted methods may allow for the definitions of the changes in the glucose and insulin curves following the ingestion of either carbohydrate-based and other foods. More debate is still raised on the clinical meaning of these classifications when used at a population level, while emphasis is raised on the approach to carbohydrate metabolism on an individual basis. Within these ranges of applications, other compounds, such as plant polyphenols, may favourably add synergic effects through the modulation of carbohydrate digestion and glucose metabolic steps, resulting in lowering postprandial glucose and insulin levels. Finally, a growing knowledge suggests that the balance of dietary fructose and individual physical activity represent the key point to address the compound towards either positive, energy sparing effects, or a degenerative metabolic burden. The carbohydrate quality within a whole dietary and lifestyle pattern may therefore challenge the individual balance towards health or disease.

Breakfast foods with lower glycaemic responses are associated with better body weight control. Glycaemic index (GI) values of some commonly consumed breakfast foods in Italy were determined and compared, along with macronutrients. Cakes/pastries were low-medium GI (44-60), with high-sugar and saturated fat and low-fibre. Generally, mueslis and breads were medium GI (62-66 and 59-76, respectively) with higher fibre and lower saturated fat and sugar. The addition of spreads to bread lowered GI (47-66) but increased sugar and saturated fat.

Breakfast consumption can entail nutritional advantages positively affecting food choices. This study investigated the effect of minor changes in breakfast composition on the perceived attributes of foods, both at breakfast and at lunchtime. Four breakfasts were defined considering nutritional and perceptual factors. Three breakfasts varied just for a single cereal-based chocolate-containing food item, while a control breakfast mimicked fasting conditions. Breakfast perception was assessed before and after consumption. Subjects rated breakfast energy content on the basis of single items, while judged breakfast healthiness as a whole, suggesting that the combination of different ingredients can modify the perceived health value of foods. Additionally, 4 h after breakfast, a perceptual evaluation of lunch-related food images was performed, without differences among breakfasts. This study extends current knowledge on the relationship between subjective perceptual attributes and objective energy value and food composition, as well as on breakfast impact on food perception at lunchtime.

Naringenin, together with its glycosidic forms, is a flavanone abundant in grapefruit and orange. It has been detected in human plasma, following citrus juice intake, at sub-µmolar concentrations, and its main phase II conjugated metabolites (naringenin-7-O-glucuronide and narigenin-4'-O-glucuronide) have been identified in urine. Recent evidence suggests a potential active anti-inflammatory role of flavonoids on macrophages, cells actively involved in atherogenesis. The aim of this study was to evaluate the effects of naringenin and its phase II metabolites on the expression of specific genes in differently activated macrophages at concentrations coherent with dietary exposure. Results suggest that phase II metabolites, as well as the aglyconic form of naringenin, were able to perturb macrophage gene expression in directions that are not always consistent with anti-inflammatory effects. Moreover, the effects of metabolites were not always consistent with each other and with those of their aglycone, underlining the paramount importance of testing physiological forms of phytochemicals within in vitro experimental models. In vivo studies are needed to further explore these observations and investigate their practical consequences.

Green tea is a popular beverage, prepared with infusion of unfermented dried leaves of Camellia sinensis, and is one of the most relevant sources of polyphenolic compounds in the human diet. This study reports green tea flavan-3-ol absorption, metabolism and complete urinary excretion up to 48 h in 20 healthy volunteers. Urinary and tea samples were analysed by high-performance liquid chromatography coupled with tandem mass spectrometry. Green tea contained monomeric flavan-3-ols and proanthocyanidins with a total polyphenol content of 728 μmol. A total of 41 metabolites were identified in urines, all present in conjugated forms. Among these, six colonic metabolites of green tea flavan-3-ols were identified for the first time after green tea consumption in humans. The average 48 h bioavailability was close to 62%, major contributors being microbial metabolites. Some volunteer showed a 100% absorption/excretion, whereas some others were unable to efficiently absorb/excrete this class of flavonoids. This suggests that colonic ring fission metabolism could be relevant in the putative bioactivity of green tea polyphenols.