Consumption of gold kiwifruit reduces severity and duration of selected upper respiratory tract infection symptoms and increases plasma vitamin C concentration in healthy older adults.

AbstractIn the elderly, immunosenescence and malnourishment can contribute to increased risk and severity of upper respiratory tract infections(URTI). Gold kiwifruit (Actinidia chinensis ‘Hort16A’) contains nutrients important for immune function and mitigation of symptoms ofinfection, including vitamins C and E, folate, polyphenols and carotenoids. The objective of the present study was to evaluate whetherregular consumption of gold kiwifruit reduces symptoms of URTI in older people, and determine the effect it has on plasma antioxidants,and markers of oxidative stress, inflammation and immune function. A total of thirty-two community-dwelling people ($65years) partici-pated in a randomised crossover study, consuming the equivalent of four kiwifruit or two bananas daily for 4 weeks, with treatmentsseparated by a 4-week washout period. Participants completed the Wisconsin Upper Respiratory Symptom Survey-21 daily, and bloodsamples were collected at baseline and at the end of each treatment and washout period. Gold kiwifruit did not significantly reducethe overall incidence of URTI compared with banana, but significantly reduced the severity and duration of head congestion, and theduration of sore throat. Gold kiwifruit significantly increased plasma vitamin C, a-tocopherol and lutein/zeaxanthin concentrations, anderythrocyte folate concentrations, and significantly reduced plasma lipid peroxidation. No changes to innate immune function (naturalkiller cell activity, phagocytosis) or inflammation markers (high-sensitivity C-reactive protein, homocysteine) were detected. Consumptionof gold kiwifruit enhanced the concentrations of several dietary plasma analytes, which may contribute to reduced duration and severity ofselected URTI symptoms, offering a novel tool for reducing the burden of URTI in older individuals.Key words: Actinidia chinensis: Gold kiwifruit: Common cold: Influenza