Enrichment in vitamins

Abstract

Egg is a natural food that contains a great number of essential nutrients, including all the vitamins with the exception of vitamin C. The vitamin concentration of the whole egg and the distribution in the yolk and albumen is described in Table 6 of Chapter 18 (Part II). Nowadays, food is being looked at in a new way. More and more attention is being paid to the relationship of the diet to human health and well-being; as a animal product, eggs in particular represent an important part of human diet. Therefore, an improvement in the egg nutritive value might have direct positive implications for daily nutrient intake and consequently for human health. In the attempt to achieve effective food enrichment, nutrients must have a proven efficiency and their amount must be modifiable in food, in this particular case in the whole shell egg. This enrichment in the nutritive content of the shell egg is achieved through the inclusion of appropriate nutrients in the feed of the laying hen. The best known and most clearly beneficial components for egg enrichment are unsaturated fatty acids (omega-3 and conjugated linoleic fatty acids), vitamins (above all fat-soluble ones and especially vitamin E), and a few minerals. Information related to egg enrichment in fatty acids and minerals is described in Chapters 20 and 22 of Part II. Vitamin concentration in hen feed is the most important factor in determining vitamin content in the egg. This is particularly true for fat-soluble vitamins. The lipid components of the egg, including fat-soluble vitamins, are only present in the yolk. During the last 10 days before hen ovulation, the lipids of dietary origin are absorbed and deposited in the yolk in the last phase of its formation. As the fat-soluble vitamin concentration of the feed increases, so does the vitamin content of the egg yolk. The most relevant data related to egg vitamin enrichment through nutrition are now presented, with special attention paid to vitamins E, A, and D. In particular the vitamin enrichment level reached in the egg and the implications on daily vitamin intake and consequently on consumer health are discussed. More information about this subject can be found in the review articles of Stadelman and Pratt (1989) and Naber (1993). © Springer-Verlag Berlin Heidelberg 2007.