337. The supplementary relationships between the proteins of dairy products and those of bread and potato as affected by the method of feeding. With a note on the value of soya-bean protein

Abstract

1. The biological value of proteins at an 8% level of protein intake measured on rats by the method of Mitchell (7, 10) was 52 for white bread of 73% extraction, 76 for Cheddar cheese, 75 for a mixture of both foods when each supplied 50% of the protein, and 67 when the two sources of protein were given on alternate days. The true digestibilities were, respectively, 99, 100, 98 and 99.2. Similar experiments with dried skim milk and dried cooked potatoes yielded biological values of 71 for potato, 89 for milk, 86 for the mixture and 81 for the substances fed separately on alternate days. The true digestibilities were, respectively, 82, 90, 82 and 87.3. An attempt to carry out experiments of the same type with dried whey and dried potato failed because of deaths of some rats receiving the whey diet, probably because of its high content of lactose. A biological value of 76 was obtained for the potato proteins and of 70 for a mixture of whey and potato in which whey supplied 25% of the protein. The true digestibilities were, respectively, 82 and 68.4. The biological value and the true digestibility of the proteins of a sample of edible soya-bean flour were, respectively, 73 and 90.5. It is concluded that there is a marked supplementary relationship between the proteins of milk and potato and those of bread and cheese when the members of each pair supply equal amounts of protein and when they are given together. No supplementary relationship is exhibited when the sources of protein are given separately on alternate days.

Protein Distribution and Muscle-Related Outcomes: Does the Evidence Support the Concept?

“…When the body is in zero nitrogen balance, protein breakdown presumably equals protein synthesis [2]. By the mid-20th century, it was understood that protein synthesis fluctuated in response to essential amino acid consumption [3][4][5][6]. Consequently, the meal-to-meal pattern of protein intake-the within-day protein distribution-was hypothesized to influence daily protein synthesis, protein equilibrium, and nitrogen balance [7].…”

Amino Acids and Proteins, Their Place in Human Nutrition Problems

“…In the same way, mixtures of proteins which to some degree supplement one another's amino acid deficiencies give better growth than the same proteins supplied at separate feedings. This was demonstrated by Henry and Kon for the combinations of milk and potato and of bread and cheese (54), and by Geiger for several other proteins (41).…”

“…At 39 grams of protein per loaf, this amount of bread would make an annual contribution of 4680 grams of protein to the average individual's diet. In weight, this is equal to the protein contained in approximately 54 pounds of fresh lean beef, 140 quarts of milk, or 660 eggs (775), but in protein efficiency it is equivalent to only about half these values.…”

Significance of Proteins in Nutrition

“…It is very necessary that no key amino-acid be lacking, otherwise it will form a limiting factor in growth or even in maintenance. Dissociation in time of ingestion of the essential amino-acids, even though all the necessary ones are provided within the 24 hours (Henry and Kon, 1946), has been demonstrated to lead to inefficient functioning, as all are required at the same time. Further, dissociation in time of ingestion of protein and carbohydrate leads to an inefficient use of the protein (Cuthbertson and Munro, 1939;Cuthbertson, Munro, and McCutcheon, 1940).…”