To determine whether supplementation with an antioxidant rich berry-based tea product can improve cardiovascular and respiratory parameters in healthy participants.
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Introduction: Oxidative stress, caused by free radicals, contributes towards the pathology of many conditions, including those of the cardiovascular and respiratory systems. Antioxidants can be consumed through dietary sources and work to counteract the harmful effects of these free radicals. Polyphenolic compounds are a category of antioxidant molecules which are found abundantly in tea. Previous research has demonstrated that tea, such as green or black varieties, may have positive effects on blood pressure and lung function. However, these benefits have usually only been proven in older, hypertensive or obese individuals. Although berries are rich sources of antioxidants, berry tea has never been the focus of research. Investigating the polyphenolic content, antioxidant capacity, palatability and cardiorespiratory health benefits of berry tea will help determine if this is a suitable alternative to green or black. Aim: To determine whether supplementation with an antioxidant rich berry-based tea product can improve cardiovascular and respiratory parameters in healthy participants. Methodology: One green tea and four berry teas were analysed through FRAP and Folin–Ciocalteu assays to estimate their antioxidant capacity and total polyphenolic content. The berry tea with the highest laboratory results was selected for the intervention. Healthy participants (n=14) were recruited to take part in this study. They were asked to consume two cups of berry tea per day for 7 days. Blood pressure measurements and lung function tests (VC, FVC, FEV1, FEV1:FVC) were recorded before and after the intervention period. The palatability of the five teas was assessed using a 0-10 scale questionnaire (0 being the worst and 10 being the best score). Participants were also asked to complete a physical activity questionnaire and 4-day diet diary during the intervention. Two groups were formed, based on how frequently they consumed fruits and vegetables. Results: Green tea was significantly higher than the berry teas with regards to antioxidant capacity and total polyphenolic content. Although the berry teas had similar laboratory results, ASDA Strawberry and Forrest Fruits had the highest concentrations (3.86±0.17 mg/g FSE and 189±0.7 mg/g GAE). Green tea had the lowest average palatability score, with a value of 5±3. There was no significant difference in the blood pressure and lung function results for either group following the intervention period. Conclusion: It can be concluded that consuming 2 cups of ASDA Strawberry and Forest Fruits tea per day for 7 days had no significant effect on blood pressure, VC, FVC, FEV1 and FEV1:FVC in the 14 healthy participants who took part in this study. Future research including different population groups, longer intervention periods and higher polyphenolic concentrations is necessary to determine if berry tea is a suitable alternative to green.