Vitamin B12 is a water-soluble vitamin that keeps your nerves and red blood cells healthy. It is responsible for the smooth functioning of several critical body processes. It is possible for the body to develop a vitamin B12 deficiency. This deficiency is usually reported with symptoms of fatigue. Strict vegetarians, heavy drinkers and smokers, pregnant and breast-feeding women, and the elderly usually require vitamin B12 supplements. Sometimes our body, mainly our digestive system, is not able to absorb this vitamin well. This can happen when a person has pernicious anemia, celiac disease, Crohn's disease, bacteria growth in the small intestine, or a parasite. People suffering from these conditions may need vitamin B12 supplements as well.
A deficiency in vitamin B12 can result in a host of illnesses like anemia, fatigue, weakness, constipation, loss of appetite, weight loss, depression, poor memory, soreness of the mouth, asthma, vision problems, and a low sperm count.