The University of Otago research showed that feelings of vitality were boosted by eating two kiwifruit a day for two weeks.
And the effects of eating the fruit were stronger than for other people taking vitamin C mainly through a supplement tablet.
Researchers from the psychology department, in Dunedin, and the university’s Centre for Free Radical Research in Christchurch ran a placebo-controlled test of whether increasing vitamin C through whole fruit or tablets could improve feelings of vitality or "zest for life".
Researchers studied 167 participants aged 18 to 35 with low levels of vitamin C and randomly divided them into three groups; a kiwifruit group, a vitamin C tablet group (250 mg) and a placebo-tablet group.
Each day for four weeks, they were asked to eat two kiwifruit, a fruit very high in vitamin C, or take a tablet.
Vitamin C levels in the kiwifruit group and vitamin C tablet group increased to normal within two weeks.
However, lead author Associate Prof Tamlin Conner, of Otago, said the benefits of the whole fruit, excluding skin, were stronger and occurred for more people, lessening fatigue and improving mood and wellbeing, whereas the tablet’s benefits were mainly in those "quite deficient in vitamin C".
The study was published in open access journal Nutrients.
The research was funded by kiwifruit marketing company Zespri, but was undertaken independently.
