Egg yolks are a nutrient-dense food that provide a variety of essential vitamins and minerals. They are an excellent source of protein, containing about 6 grams per large egg. Egg yolks are also a good source of healthy fats, including monounsaturated and polyunsaturated fats. Additionally, egg yolks are a great source of vitamins A, D, E, and K, as well as B vitamins, such as folate, riboflavin, and choline.