Naturally enhanced eggs as a source of vitamin D: A review

Background: It is estimated that on annual basis 40% of the European population is either vitamin D insufficient/deficient. A way to increase the vitamin D intake is to fortify a broader range of foods or by increasing the natural vitamin D content in food sources that already contain vitamin D. Eggs is once again considered part of a healthy varied diet and eggs contain a wide range of micro nutrients including vitamin D. Scope and approach: Review of production methods to naturally enhance eggs with vitamin D, and discussion of the perspectives of vitamin D enhanced eggs as part of the strategy to increase the dietary intake of vitamin D. Key findings and conclusions: There are three ways to naturally enhance the vitamin D content in eggs: feeding more vitamin D₃/25(OH)D₃ to the hens, exposing the hens to UVB and exposing liquid egg products to UVB. Naturally enhanced eggs can contribute to increased vitamin D intake. An inter-trial linear relationship between vitamin D₃ in feed and vitamin D₃ in eggs was found. Within the linear range a maximum of 20 μg/100 g yolk was obtained with feed contain 617.5 μg/kg feed. Feed can provide higher levels of vitamin D in eggs than UVB exposure of the hens. However, the European maximum for vitamin D in feed for layers at 80 μg/kg limits the beneficial effect. Vitamin D content in liquid egg products can be tailored by adjusting the UVB dose, however further research is needed.