The health benefits of vitamin B-12 include the support of the nervous system and blood cells, according to MedlinePlus. It is important for overall metabolism, which involves nearly every system in the body, including digestion, respiration, the circulation of blood and absorption.
Vitamin B-12 protects against pernicious anemia, according to WebMD. This is a disease that affects mostly older people. The reason for this may be that the stomachs of older people do not produce enough intrinsic factor, which is necessary to metabolize Vitamin B-12, according to Wikipedia. Because of this, some older people receive vitamin B-12 injections.
Vitamin B-12 also shows promise in treating age-related macular degeneration, according to WebMD. Vitamin B-12 appears especially effective for this purpose when used in combination with other vitamins, such as folic acid and vitamin B-6.
Older people who are in the early stages of dementia may also benefit from vitamin B-12, according to HowStuffWorks. The vitamin also eases the symptoms of asthma in children and helps AIDS patients by preventing the HIV virus from replicating. Vitamin B-12 is useful in improving male sperm counts and sperm motility. Those who suffer from tinnitus, or ringing in the ears, are often lacking optimal levels of vitamin B-12.