Investigating the effect of gold kiwifruit consumption on the incidence and symptoms of upper respiratory tract infections in preschool children : a thesis presented in partial fulfilment of the requirements for the degree of Masters of Sciences [sic] in Human Nutrition and Human Health at Massey University, Auckland, New Zealand
Evidence suggests that diets rich in fruits and vegetables boost the body‟s natural defences against diseases caused by infection. Gold kiwifruit is rich in vitamin C and contains several phytochemicals that may influence immune function. The effect of consumption of ZESPRI® GOLD kiwifruit on the incidence, and symptoms of upper respiratory tract infection (URTI) have been investigated in children attending local crèches and play-centres. In a randomised, crossover trial, 66 children (aged two to five years) were randomised into one of two groups following a 2-week washout period and consumed an equivalent of 2 servings of gold kiwifruit (group A) or 2 servings of banana (group B) daily for 4 weeks. This was followed by a 2-week washout period and a cross-over of the treatments i.e. group A consumed 2 servings of banana and group B consumed 2 servings of gold kiwifruit for a further 4 weeks, followed by a final 2-week washout period. Parents completed a daily questionnaire of URTI symptoms, the validated Canadian Acute Respiratory Illness and Flu Scale (CARIFS), which assessed the incidence of cold-and flu-like illnesses and the severity of those symptoms. The fruit and vegetable consumption of the children along with their food liking was also investigated at baseline and at the end of the intervention. Additionally, children‟s fruit and vegetable eating habits along with their parent‟s motivation to provide them with fruits and vegetables were also investigated. The odds ratio of having a cold- or flu-like illness was 0.55 (95% (0.32, 0.94), P=0.03) for the kiwifruit intervention compared to the banana intervention. The sum of total URTI symptoms scores over the treatment periods were significantly lower for the kiwifruit treatment compared to the banana treatment (P<0.05), along with the incidence of certain URTI symptoms (including cough, headache, and feeling unwell). Children‟s fruit consumption did not differ from baseline to end but their kiwifruit liking scores improved. There was a strong positive correlation between children‟s fruit and vegetable consumption and parents‟ motivation to provide them with fruits and vegetables (r values ranged from 0.22-0.61). In conclusion; Children had a lower incidence of cold- and flu-like illnesses during the kiwifruit intervention phase of the trial compared to banana phase. Some of the URTI symptoms were significantly less during the kiwifruit intervention phase compared to the banana phase. Regular consumption of Zespri® Gold Kiwifruit during the cold & flu season may reduce the incidence or symptoms of URTI in children.