Fifth International Congress on Vegetarian Nutrition. Preface.

The Fifth International Congress on Vegetarian Nutrition was held in March 2008 at Loma Linda University, Loma Linda, CA, and the congress proceedings are presented in this supplement. The American Journal of Clinical Nutrition also has published the proceedings from the previous 4 congresses (1–4). The vegetarian congress provides a unique opportunity for researchers and health practitioners from around the world to meet, present, and discuss the core and emerging issues on vegetarian and plant-based nutrition. It serves as a forum to identify gaps that exist in vegetarian nutrition research and provides opportunities for formulating new research. Over the years, the scope and breadth of topics covered in the vegetarian congress have grown substantially. There are several dimensions to the study of vegetarian or plant-based diets. First, the traditional aspect deals with adequacy of vegetarian diets and the health status of vegetarians. When considering vegetarian diets, there are some food groups, eg, dairy, that are excluded by strict vegetarians (vegans) but included by others (lactoovovegetarians). Given that there is controversy regarding whether or not dairy foods should be part of a healthy vegetarian diet, a scientific debate was organized in this congress to deal with this issue. Although vegetarians avoid or limit the intake of animal foods, they tend to consume more of certain plant foods, such as soy and nuts. Although these foods are not unique to vegetarians, they contribute considerably to the protein and fat content of vegetarian and plant-exclusive diets. The core aspect of vegetarian diets, the point (5) and counterpoint (6) arguments for the inclusion of dairy foods, and the recent advances in reporting the health effects of soy (7–9) and nuts (10–12) all are presented in this supplement. The second dimension of vegetarian diets is their role in the prevention and treatment of chronic diseases, including heart disease, diabetes, obesity, and cancer. One of the questions that vegetarians often have is whether or not plant sources of n–3 (omega-3) fatty acids can provide health benefits equivalent to those conferred by marine n–3 fatty acids. Comparing plant with marine n–3 fatty acids is complex; however, an attempt was made to address this comparison with respect to selected cardiovascular disease outcomes (13). Also, the role of plant-based diets in the prevention of cancer (14–16) and a few other selected chronic diseases was featured in some symposia and many of them are presented in this supplement. Since the previous congress, in 2002, there has been a steady increase in the understanding and awareness among the general public and the scientific communities of the environmental consequences of food production and the implications of dietary choices on climate change. Current research and future perspectives on the interaction of diet and environment (17–19), which is the third dimension of vegetarian diets, were presented in a special symposium at this congress and are included in this supplement. Accumulating evidence on the health benefits of vegetarian and plant-based diets makes it imperative to translate this knowledge for nutrition education and for influencing nutrition policy. At this congress, an expert panel discussed the existing evidence that supports the positioning of selected plant foods more prominently in the upcoming dietary guidelines (20). A presentation on food synergy (21) emphasizing food-based rather than nutrient-based dietary recommendations provided the framework for this panel discussion. The panelists also deliberated on the potential challenges that may be encountered in the process of bringing about these changes and on possible solutions. The summary of this expert panel is presented in this supplement. Besides the major symposia, the congress included short oral presentations and poster sessions, which added to the international diversity and broadened the topics presented at the congress. The congress was well attended, with . 750 participants, almost double those who attended the previous congress in 2002. We sincerely thank all the congress speakers, members of the organizing and scientific planning committees and the International Advisory Board, and the reviewers of the manuscripts for this supplement. It is our hope that the information presented here not only will advance our knowledge in the various dimensions of vegetarian nutrition but also will empower health professionals who counsel vegetarians and others who choose plant-based diets. (Other articles in this supplement to the Journal include references 22–31.)