The other day I heard a few friends chatting: egg yolk can not eat! Is that true? When it comes to vitamins, there is no doubt that most of them are concentrated in the egg yolk. Egg yolks contain valuable vitamins A, D, E and K. These are all fat-soluble vitamins and there is no trace of them in the egg whites. Even the water-soluble B vitamins are mostly found in the yolk. In addition, part of that light yellow color in the yolk comes from the color of riboflavin, which is vitamin B2, which can prevent common ailments such as cracked corners of the mouth, tongue inflammation, sore lips, and cracks. Various trace elements are also concentrated in the egg yolk as well. Egg yolks have a large amount of phosphorus, and quite a bit of iron. Although the absorption rate of iron in egg yolks is relatively low, it still plays an important role for infants who cannot eat meat. Also, all the lecithin in eggs comes from the yolk, and lecithin provides choline, which helps synthesize an important neurotransmitter, acetylcholine. Therefore, the first complementary food for infants is often the egg yolk. Egg yolks are beneficial for children’s iron supplementation, as well as for their brain development. In addition to the rich nutrients and healthful lecithin, egg yolks also contain unexpectedly healthy ingredients: they are lutein and zeaxanthin. Both lutein and zeaxanthin are carotenoids, but they cannot be converted into vitamin A. Nevertheless, they have strong antioxidant properties, especially for eye protection. The imaging part of the human eye is the retina, which has a “macula”, the yellow color of which comes from lutein and zeaxanthin. These two substances help the eyes filter harmful ultraviolet rays, slow down the aging of the eyes, and prevent eye diseases such as retinal macular degeneration and cataracts. Therefore, it is better to eat eggs in their entirety.