Protein milk, copper-containing

Samuelsson (1960) observed that most of the natural copper associated with the cream phase can be removed by washing with water and that the actual fat globule membrane proteins contain approximately 4%o of the total natural copper content. Nevertheless, the value represents the highest concentration of copper per gram of protein in the milk system. Koops (1969) stated that although the amount of natu-... 

Animal origin products such as eggs, milk, fish, red meats and poultry contain low amounts of manganese. Absorption of such minerals as iron, copper, phosphorus and calcium is superior from animals products than from plant-origin foods. As reported by Kies et al. (in this book), manganese apparently is better absorbed by humans from meals containing meat and fish than from those containing plant-protein replacement products. Because of the low content... 

In Table I it is seen that the addition of more iron was of no assistance in increasing the hemoglobin level. In this instance it actually decreased the hemoglobin and hematocrit levels slightly. Likewise, the concentration of iron in the liver was, if anything, increased. It was only when copper was added that one saw a measurable increase in hemoglobin and hematocrit levels. When both iron and copper were added, the effect was no better than when copper by itself was added. In this instance the diet contained 8.5% protein. This amount is basically what was present in the breakfast cereal without any further protein supplementation. Others have been quick to point out that this situation is not realistic because these cereals are typically consumed with milk. It is reasonable, therefore, to parallel this experiment with one in which casein is added to the diet. 

Although cow and human milk resemble each other superficially, there are many quantitative and qualitative differences between the two types of milk (see Table 4-1). The water and fat content of cow milk is the same as that of human milk, but cow milk contains three times as much minerals and proteins as human milk. In contrast, the lactose content of cow milk is only two-thirds that of human milk. At first approximation, it seems that a product similar to human milk can be obtained simply by diluting cow milk with two volumes of water and by supplementing it with carbohydrates. But a more careful comparison of the composition of cow milk and human milk indicates that cow milk is low in iron, copper, vitamins A and E, essential fatty acids, and essential amino acids. Therefore, the dietary qualities of human milk are not completely matched by the administration of cow milk. 

Modified milks with low protein content, especially those based on demineralised whey, may not contain sufficient zinc, copper and other trace metals, since many trace elements are bound to the protein and are also removed during whey demineralisation, whose purpose is to reduce the excess of sodium and potassium. Supplements of trace elements are frequently poorly absorbed Trace mineral deficiencies may result from otherwise desirable modifications to milk for infant formulae. Pre-term infants are at greatest risk of deficiency, as they have inadequate stores laid down at the time of birth. Human milk provides the safest utilisable source of trace minerals, though preterm infants may require additional supplies. 

The issue of bioavailability from food sources and the interactions between food groups and copper availability remains a critical question. Lonnerdal et al. demonstrated that heat treatment of cows milk formula decreases the copper bioavailability. Transitional complexes form in the milk upon heating that have a similar configuration to copper and thereby directly inhibit copper absorption. High doses of zinc also reduce copper bioavailability, as does combined iron and zinc supplementation. The dilemma is how to prepare an infant formula containing adequate copper, iron, and zinc that will meet the RDA for copper. Other nutrients dramatically affect copper absorption from foods. Soy protein-based diets promote less copper retention in tissues than lactalbumin-based diets. However, it is unclear if this effect is solely due to the soy protein composition or to the higher zinc in these soy-based formulas. In animals, phytate causes a drop in serum copper but human stable isotope studies reveal no... 

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