1. From the Department of Human Nutritional Sciences, University of Manitoba, Winnipeg, Manitoba, Canada; the
2. Departments of Ophthalmology and3Physiology, University of Alberta, Edmonton, Alberta, Canada;
3. Harvard Medical School, Cambridge, Massachusetts; the
4. Department of Nutritional Sciences, University of Toronto, Toronto, Ontario, Canada; and the6Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada.