Part 1: Setting the scene: general features associated with vegetarian diets. Vegetarian diets: definitions and pitfalls in interpreting literature on health effects of vegetarianism -- Attitudes toward meat and plants in vegetarians -- Nutrition knowledge of vegetarians -- Vegetarianism and eating disorders -- Cognitive processes underlying vegetarianism as assessed by brain imaging -- Geographic aspects of vegetarianism: vegetarians in India -- Religious variations in vegetarian diets and impact on health status of children: perspectives from traditional vegetarian societies -- Dietary transition: longterm trends, animal versus plant energy intake, and sustainability issues -- Plant-based diets for mitigating climate change -- Barriers to increasing plant protein consumption in Western populations -- Part 2: Setting the scene: specific dietary characteristics of vegetarian diet and their relation to health. Dietary patterns in plant-based, vegetarian, and omnivorous diets -- Meat consumption and health outcomes -- Fruits, vegetables, and health: evidence from meta-analyses of prospective epidemiological studies -- Whole grains and disease risk -- Nut intake and health -- New concepts and paradigms for the protective effects of plant-based food components in relation to food complexity -- Part 3: The relations between vegetarian diets and health and disease. Bone health and vegan diets -- Weight maintenance and weight loss: the adoption of diets based on predominantly plants -- Cancer risk and vegetarian diets -- Vegetarian diets and the risk of type 2 diabetes -- Vegetarian diets in people with type 2 diabetes -- Blood pressure and vegetarian diets -- Ischemic heart disease in vegetarians and those consuming a predominantly plant-based diet -- Vegetarian diets and the microbiome -- Vegetarianism and the risk of gastroesophageal reflux disease -- Defecation and stools in vegetarians: implications in health and disease -- Plant-based diets and asthma -- Vegetarian diet and possible mechanisms for impact on mood -- Part 4: Life events. Vegetarian infants and complementary feeding -- Nutritional status of vegetarian children -- Food and meals in vegetarian children and adolescents -- Vegetarian and plant-based diets in pregnancy -- Vegetarian diet and menopausal women -- Nutritional profiles of elderly vegetarians -- Part 5: Nutrients and other substances intake and status. plant protein, animal protein, and protein quality -- Plant protein, animal protein, and cardiometabolic health -- Polyunsaturated fatty acid status in vegetarians -- Implications of a plant-based diet on zinc requirements and nutritional status -- Plant-based diets and iron status -- Plant-based diets and selenium intake and status -- B vitamins intake and plasma homocysteine in vegetarians -- Iodine status, thyroid function, and vegetarianism -- Vitamin B12 deficiency in vegetarians -- Probiotics in nondairy products -- Exposure to pesticide residues and contaminants of the vegetarian population: French data.