Lack of certain vitamins in the diet leads to diseases. Lack of the vitamin A results in eye diseased and night blindness. This vitamin is present in animal fat such as egg yolk,milk,cream and fish-liver oil. Vitamin D is responsible for the formation of healthy bone tissue. It is found in similar foods to those in which vitamin A is found and can also be manufactured by the body from the action of sunlight on the skin. The lack of vitamin C causes scurvy,or suffering from bleeding gums and extreme weakness. This can be prevented by the addition of fresh fruit and vegetable to the diet.