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. Amino acids are the building blocks (monomers) of proteins. Twenty different amino acids are used to make the body's proteins. Of these nine are called essential (meaning they can only be obtained from the food we eat) and eleven are non-essential (they may be synthesised in the body though they are usually obtained from food).