Seasonal Variations in Dietary Flavonoid Content of Edible Plants

Flavonoids are ubiquitous compounds commonly found in vegetables, fruits and other plant foods. Although not considered nutrients per se, consumption of various flavonoids is associated with established health benefits. Their biosynthesis, and therefore concentrations, are influenced by genetic, geographic and environmental conditions. Flavonoid content in foods can be seasonal, potentially influencing their total intake and biovailability. In view of the potential role of flavonoids in human health, studies published over an 11-year period (2009 to 2020) investigating links between flavonoid content and season in edible and medicinal plants, were examined. The limited studies to date focus on a small range of plant species. Within this, there is consistent evidence that flavonoid content varies according to season, particularly in relation to plant genotype and environmental conditions such as temperature, geographic location, light conditions/UV radiation and drought/water stress. Seven studies detected highest total flavonoid content at the end of winter and lowest in mid-autumn. From the included studies, rutin was the most commonly studied flavonoid, showing its highest levels in both spring and winter. These findings suggest studies on flavonoid intake should include seasonal considerations. Further studies on seasonal variations of common dietary flavonoids are warranted to enable such studies

A systematic review of baseline psychosocial characterisation in dietary randomised controlled trials for weight loss

Background/objective: To investigate the extent of baseline psychosocial characterisation of subjects in published dietary randomised controlled trials (RCTs) for weight loss. Subjects/methods: Systematic review of adequately sized (n⩾10) RCTs comprising ⩾1 diet-alone arm for weight loss were included for this systematic review. More specifically, trials included overweight (body mass index >25 kg/m2) adults, were of duration ⩾8 weeks and had body weight as the primary outcome. Exclusion criteria included specific psychological intervention (for example, Cognitive Behaviour Therapy (CBT)), use of web-based tools, use of supplements, liquid diets, replacement meals and very-low calorie diets. Physical activity intervention was restricted to general exercise only (not supervised or prescribed, for example, VO2 maximum level). Results: Of 176 weight-loss RCTs published during 2008–2010, 15 met selection criteria and were assessed for reported psychological characterisation of subjects. All studies reported standard characterisation of clinical and biochemical characteristics of subjects. Eleven studies reported no psychological attributes of subjects (three of these did exclude those taking psychoactive medication). Three studies collected data on particular aspects of psychology related to specific research objectives (figure scale rating, satiety and quality-of-life). Only one study provided a comprehensive background on psychological attributes of subjects. Conclusion: Better characterisation in behaviour-change interventions will reduce potential confounding and enhance generalisability of such studies