Blood type A donors can donate to recipients with blood types A and AB. Donors of blood type O can give to people with blood types A, B, AB, and O. (O is the universal donor; donors with O blood are compatible with any other blood type). The ability of someone who is blood type O to function as a blood donor depends on many factors such as age, health, etc. Blood donors should not be discouraged from donating because they are blood type O. In fact, blood type O donors are needed the most. Anyone can donate blood, regardless of age, gender, or blood type. The only criteria for donors is that they must be in good health and at least 17 years old. Young people who have never donated blood may want to consider doing so now before going to bed one night and finding out you're pregnant! In general, people who are blood type O can accept blood of all other types even if they don't have their own type. For example, someone who is blood type O can accept blood products made from cells of individuals with different blood types. Also, people who are blood type O often do not require transfusions because their bodies produce enough blood cells on its own. However, some studies show that individuals with blood type O may need more red blood cells than others who have another blood type.