**Acknowledgments**

We thank the young men who participated in this study, Jo Kepple and her staff at Primorus Clinical Trials Unit, Lynley Drummond for consultation on study design, Heather Webb for technical assistance, and Juliet Pullar for editing the manuscript. Sources of Support: Co-funding was provided by the New Zealand Ministry of Business, Innovation & Employment and Zespri International Ltd., Mount Maunganui, New Zealand.
