Eggs are one the most nutrient dense foods. A nutrient dense food is one that provides a relatively high proportion of essential nutrients per calorie. One large egg provides about 70 kilocalories and 6 grams of high quality, easily digested protein and all the essential amino acids. Eggs are also a significant source of vitamins and minerals (e.g., riboflavin, folate, vitamin B-6, vitamin B-12, vitamin D, vitamin E, iron, phosphorus, and zinc). A large egg also contains about 4-5 g of fat in the yolk, mainly the healthy unsaturated type. Egg yolks also contain choline, an important substance necessary for fat breakdown, the membranes of nearly every cell in the body, and production of neurotransmitters. From an economic perspective, eggs are lower in cost than many other animal-protein foods that make similar nutritional contributions.