Keto Lux states that severe malnutrition has been reported in infants and toddlers fed inappropriate vegetarian diets as well as deficiencies of iron, vitamin B-12, and vitamin D. So, the greater the variety of foods that make up the diet, the better the chances that all the nutrients will be provided. (2) In another study found in The American Journal of Clinical Nutrition, Hebbelinck et al. concluded that a Lacto-Ovo vegetarian diet sustains adequate physical growth and maturation.