Biological Availability of Lysine

Abstract

Values for the biological availability of the lysine in 7 different purified proteins, and the proteins of three cereals and two milk powders, were determined by measuring their value as supplements to a wheat gluten diet low in lysine. The availability of the lysine in beef was 76%, from gelatin 74%, and that in the other purified proteins tested was 90 to 104% as calculated from simple growth data. Higher values, particularly for beef and gelatin, were obtained when availability was calculated from weight gain per unit of food consumed. Evidence was obtained suggesting that the second method of computing availability was more accurate. Values for the availability of the lysine in three cereal proteins differed considerably, the value for rice being highest with those for wheat and corn following in order. The lysine of roller-dried skim milk was less available than that of a spray-dried preparation. Lysine availability was not appreciably affected by changes in the level of the test protein.