The availability of lysine in groundnut biscuits used in the treatment of kwashiorkor.

Malnourished children under treatment in the wards of the Infantile Malnutrition Research Unit, Kampala, have for several years received biscuit meals made largely from groundnuts, with smaller quantities of maize and wheat flours, cottonseed oil, sugar and skim-milk powder. The meals have been of two chief kinds. In the first, 8 or 15 yo skim-milk powder was cooked with the other ingredients, but in the second the powder was added after the other ingredients had been cooked and milled. The recipes were adjusted so that the total protein of the mixtures was always about 20 yo. The value of the meals has been compared with that of a diet providing the same amount of protein entirely from milk. The milk diet appeared to be excellent in every way; its ability to produce changes in clinical condition and composition of serum, and to promote nitrogen retention, provided a useful set of standards. In a long series of experiments (R. F. A. Dean, to be published) it was found that the biscuit containing 15 yo skim-milk powder added before cooking, although fairly satisfactory, failed to produce the standard changes. On the other hand, biscuit of the other kind-with 1 5 % powder added after cooking-was the equal of the milk diet in almost every way. The most likely explanation of the differences in the results was that cooking the biscuit reduced the value of the protein. It has been known for many years that proteins from vegetable and animal sources may be damaged by heat. One of the suggested causes is a change in amino acids that makes them unavailable for metabolic processes, and there is evidence that lysine is easily susceptible to the change, probably by the blocking of its €-amino groups. From a series of feeding trials with rats, Block, Cannon, Wissler, Steffee, Straube, Frazier & Woolridge (1946) reported that cooking the mixed ingredients of a cake mixture reduced the protein efficiency, which was further decreased by toasting slices of the cake. The protein efficiency was restored by supplementing the baked and toasted cake with lysine. Carpenter, Ellinger, Munro & Rolfe (1957) found that the biological values of various proteins were closely correlated with the numbers of free €-amino groups of lysine present. The possibility of damage to the lysine of our biscuit meals was of particular interest because the