Vitamin B12 helps the body make healthy red blood cells and helps keep nerve cells healthy. It is found in animal foods, including meat, fish, eggs, milk, and other dairy products. The most common cause of pernicious anemia is the loss of stomach cells that make intrinsic factor. Intrinsic factor helps the body absorb vitamin B12 in the intestine. The loss of parietal cells may be due to destruction by the body's own immune system.
The family system. According to Bowen, a family is a system in which each member had a role to play and rules to respect. Members of the system are expected to respond to each other in a certain way according to their role, which is determined by relationship agreements.
By the close of the twentieth century family systems theory had become one of the major theoretical foundations guiding empirical investigations into the study of families and from which clinical interventions and programmatic work with families were being developed.