Enfamil Reguline Ready-to-use 8 oz. Bottle, 160 Calories Per Bottle. Enfamil Reguline is specifically designed to help support digestive health and promote comfortable stools. It is designed to be fed when perceived stooling issues, such as occasional difficult bowel movements, are causes of parental concern. Enfamil Reguline is designed to provide the sole source of nutrition for infants up to age 6 months and provide a major source of nutrition for the remainder of the first year.