Biofortification of hen eggs: vitamins and carotenoids

The dependence of the vitamin content in the egg from the content in the chicken feed represents the saturation curves (V.M. Kodentsova et al., 2005; K. Hebert et al., 2005; S. Leeson et al., 2004; A.L. Shtele, 2004; S. Grobas et al., 2002). The effectiveness of the various forms of vitamins for enrichment of chicken feed and the use for this purpose of herbal supplements had been analyzed (P. Mattila et al., 2004; P.H. Mattila et al., 2011; M. Hammershøj et al., 2010, J.A. Moreno et al., 2016). The optimal content of vitamins and carotenoids in the poultry feed results in an increase to the maximum level of vitamins and carotenoids in the egg that makes them a significant source of vitamins D, E, B and carotenoid for humans. One such egg can provide up to 40-50 % of the recommended daily intake of vitamins D, B12, A, pantothenic acid, 30 % of vitamin E, 20 % of folate, 10 % of vitamin A, 12 % of vitamin B2, and up to 30 % of the adequate level of lutein intake. The advantage of biofortification is biotransformation in the chicken’s body of synthetic vitamins added to food into their natural form, which deprives the arguments of opponents of enrichment of food products with synthetic vitamins. Comparison of the addition of different forms of vitamins showed that D3 in the diet more effectively increased the vitamin content in egg yolk (P. Mattila et al., 2004). If the chicken feed contains vitamin D only as 25OHD3, then vitamin D in the form of cholecalciferol may be completely absent in the yolk (P.H. Matvila et al., 2011). Irradiation of chicken with ultraviolet light or free-range farming in the natural sunlight may provide an original, safe and natural alternative to produce vitamin D-enriched eggs (A. Schutkowski et al, 2013; J. Kühn et al., 2014, 2015) and chicken meat without the risk of overdose of this vitamin. By increasing the content of lutein in the yolk of a chicken egg, the bioavailability of this carotenoid can be substantially increased as compared to plant sources (G.J. Handelman et al., 1999). The enrichment of eggs with vitamins meets the criteria for the fortified foods (V.M. Kodentsova et al., 2010). Increasing the level of all vitamins in hen diet resulted in a simultaneous increase in the content of all vitamins in eggs (H. Zang et al., 2011). Biofortification has clear advantages over the technological enrichment since synthetic vitamins received from feed are converted into natural ones in hen body. Biofortification of eggs with vitamins is one of the most promising strategies to increase consumption of vitamins for population (M.S. Calvoa et al., 2013).