Vitamin B is more often referred to today as the B vitamins to better relate that it is actually a group of 8 different vitamins, with varying functions and sources. B vitamins, like vitamin C, are water soluble, which means that extra levels of B vitamins are excreted by the body, though small amounts are stored in the liver and toxicity, while rare, is possible.
Most people will recognize many of the B vitamins by name. They include thiamine, riboflavin, and niacin (B1, 2, and 3, respectively), as well as folic acid (B9). The other four B vitamins are less commonly referred to and are: pyridoxine (B6), cyanocobalamin (B12), pantothenic acid, and biotin.
The B vitamins serve many functions in the body, including the breakdown of different kinds of foods into energy, maintenance and protection of the nervous system, production of blood cells, and maintenance of healthy skin.
Deficiencies of most B vitamins are rare, because they are found in many different food sources. While sources abound though, deficiencies can exist if someone has a condition that affects their ability to absorb or use B vitamins. Whole grain breads and cereals contain thiamine, riboflavin, pyridoxine, pantothenic acid and folic acid. Milk contains riboflavin, niacin, and vitamin B12 (cyanocobalamin). Foods with lots of protein like eggs and meats contain B vitamins, especially red and organ meats.
Alcoholics, along with being susceptible to many other health problems, can be vulnerable to thiamine deficiency, also known as beriberi. Alcohol prevents the body from properly absorbing thiamine and many alcoholics also do not eat otherwise healthy diets, so they are doubly prone to lacking this and other vitamins.
Riboflavin is very active in the maintenance of skin and other tissues, so deficiency of this vitamin can cause skin lesions and dermatitis. There has been a lot in the news in the past couple of years about the importance of folic acid for women of child bearing age. Women who have adequate levels of folic acid when they get pregnant are less likely to have babies with neural tube defects. The folic acid must be present before pregnancy because these types of birth defects occur in the first weeks of pregnancy, and oftentimes women will not even know they are pregnant yet.
You may have heard of people getting B12 shots because of a deficiency of this vitamin called pernicious anemia. This occurs particularly in people over 60, because as we age, our stomachs have less ability to produce the substance intrinsic factor, which must combine with B12 taken through food or oral supplements in order to be absorbed by the body.