Life course epidemiology in nutrition and chronic disease research: a timely discussion.

Humans are exposed to a complex and changing combination of nutritional factors during the life course, necessitating their investigation over time to capture "critical periods of sensitivity." A life course approach provides a framework to examine trajectories and long-term effects of nutritional and other risk factors, particularly the role of timing, accumulation, and temporal relationships of these exposures in relation to chronic disease development. Currently, most epidemiologic research does not sufficiently address this issue in relation to disease etiology. Although applying a life course approach would augment our knowledge about disease development, this approach presents major challenges in designing, conducting, and analyzing studies. A scientific symposium was held that reviewed emerging research and discussed methodological concerns in applying the life course approach. The research presented at this session focused on the role of timing, with the pre- and postnatal and pubertal periods as critical windows of exposure for chronic conditions. Methodological issues and complexities in analyzing and selecting datasets were highlighted. This symposium elucidated unique study designs and statistical strategies to demonstrate the strengths of this methodology, and served as a catalyst for new research in the area of nutrition and chronic disease epidemiology.