Opportunities and Challenges of an International Collaborative Pooled Analysis of Dietary Cohort Studies

International collaborative work of prospective cohort studies has been conducted for a few decades. It has provided a rich source for researchers worldwide to investigate the role of dietary factors in the development of many diseases. A pooled analysis of the existing cohort studies has strengths, including increased statistical power, increased generalizability, the disclosure of unpublished work, use of the standardized approaches, a wide range of dietary exposures, inclusion of diverse populations, and a build-up of partnerships of investigators. The advantages of pooled analyses are significant in nutritional epidemiology. An increase in statistical power and analysis of multilevel exposures in the consortium data allow us to have better insight and knowledge of dietary factors related to chronic diseases. However, facilitating data harmonization of foods, food groups, and nutrients in the consortium data remains challenging. Combining and standardizing dietary data is complex, given differences in food frequency questionnaires, foods assessed, dietary exposure categories and intake levels, the validity of the dietary assessment, and nutrient database availability across individual studies. Although there are limitations in the pooled analysis, international collaborative pooled analysis is a valuable and efficient means to produce important scientific evidence. In addition, consortial research needs to continue to expand in the era of moving toward a diverse world and precision medicine.