Daily Recommendations. Recommendations for vitamin A are based on age. Infants between 0 and 6 months require 400 mcg per day, whereas infants between 7 and 12 months need 500 mcg per day. Toddlers between 1 and 3 need 300 mcg every day.
The twenty amino acids can be divided into two groups of 10 amino acids. Ten are essential and 10 are nonessential. However, this is really not an accurate dichotomy, as there is overlap between the two groups, as is indicated in the text accompanying the following two charts:
Amino acids are the basic building blocks of the body. They are also sources of energy, like fats and carbohydrates. However, amino acids are structurally characterised by the fact that they contain nitrogen (N), whereas fats and carbohydrates do not. Therefore, only amino acids are capable of forming tissues, organs, muscles, skin and hair.