However, although it is a good source of protein, egg whites lack a number of nutrients found in the egg yolk. The yolks contain 8% of the daily value of Vitamin A, 52% of Vitamin B12, 21% of Vitamin D, and 29% of folate, while the white contains only 9% of the daily value of selenium, 1% of vitamin B5, and 6% of vitamin B2.