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:
Humans need 20 different amino acids in order to produce all the proteins in our bodies. We can synthesize 10 of the amino acids, but the other 10 either cannot be made or not made in a sufficient quantity to be of any use.