Lessons learned from randomizing infants to marine oil-supplemented formulas in nutrition trials

The effect of n-3 fatty acid intake on docosahexaenoic acid (22:6n-3) and arachidonic acid (20:4n-6) status, growth, retinal physiology, visual acuity, and development (Bayley Mental Developmental Index and Fagan Infantest) has been evaluated in infants randomized to a marine oil source of docosahexaenoic acid or to standard infant formula. This article will focus on the lessons learned in conducting these randomized trials--issues related to design, implementation, and interpretation. By addressing these issues it is hoped that several general concepts related to nutrition studies in infants can be explored that might prove useful to others who undertake clinical nutrition trials in general, and trials with n-3 and n-6 fatty acids in particular.