Lacto-ovo-vegetarian and vegan diets in children and adolescents: a systematic review and meta-analysis of nutritional and health outcomes

ABSTRACT The health implications of lacto-ovo-vegetarian and vegan diets in childhood remain debated. This meta-analysis compares lacto-ovo-vegetarian and vegan diets with omnivorous diets across a wide spectrum of nutrients and health outcomes among children <18 years worldwide without chronic disease. Searches in MEDLINE, Embase, Scopus, and Web of Science up to March 2025 identified 59 studies including 48,626 participants (7,280 lacto-ovo-vegetarians, 1289 vegans, and 40,059 omnivores). Lacto-ovo-vegetarian children consumed less energy, protein, fat, vitamin B12, vitamin D, and zinc, but more fiber, iron, folate, vitamin C, and magnesium. Vegans showed similar patterns, with particularly low calcium intake. Growth and body composition indicated a leaner phenotype: lacto-ovo-vegetarians had lower height, weight, BMI z-scores, fat mass, and bone mineral content, while vegans had shorter stature and lower BMI z-scores. Biomarkers showed lower ferritin and 25(OH)D in lacto-ovo-vegetarians, and lower hemoglobin and ferritin in vegans. Although group averages for most nutrients and biomarkers remained within pediatric reference ranges, increased odds of iron deficiency and anemia were observed in lacto-ovo-vegetarians, and vitamin B12 deficiency in vegans. Both groups showed lower total and LDL cholesterol. These findings underscore the need for careful dietary planning and supplementation in lacto-ovo-vegetarian and vegan children.