Think of vitamin B12, or cobalamin, as the Pluto of the B vitamins: small, insignificant, ignored for years, but necessary for the body's well being. Of the B family, B12 isn't as renown as niacin or as flashy as folic acid. Until fairly recently, doctors and nutritionists largely ignored cobalamin entirely unless a patient suffered from an obvious deficiency. Now they know otherwise: Our bodies require B12, even in tiny doses, to make red blood cells, convert the food we eat into energy, and maintain our nervous system.
A deficiency of B12, also known as pernicious anemia, can result in neurological disorders such as memory loss, dizziness, insomnia, or even dementia. Meat, fish, eggs, and dairy products all contain B12, to varying degrees, and most people obtain more than enough of this vitamin from those sources. Strict vegans - those who abstain from any animal products, including eggs, cheese, and milk - and the elderly, whose cobalamin intake must increase as their body's ability to extract it decreases, face the greatest risk of pernicious anemia, although pregnancy and breastfeeding, and smoking, can also trigger a B12 deficiency.
Fortunately, a little cobalmin goes a long way: For adults up to age 50 the U.S. Recommended Daily Allowance for B12 tops out at a paltry 2 micrograms. The body manufactures a substance in the stomach lining called the intrinsic factor that processes B12 from the foods we eat. In addition to animal products, B12 is a common additive in cereal, and occurs naturally in sea vegetables such as spirulina and kelp, and soy-based products, including tempeh or miso, but Linda Thoennes Farr, dietitian with the Nutrition Associates of San Antonio, cautions that it may not be in a form that the body can use. During the 1920s, researchers recommended patients suffering from pernicious anemia choke down a pound of raw beef liver daily. Fortunately for those who may find such a treatment repulsive, researchers isolated cobalamin in 1948, and today it is available as a pill or injection. To play it safe, Farr recommends that vegetarians and older people incorporate a supplement into their diet or, for those who totally eliminate animal from their diet,"a cobalamin injection every three months."
It may seem a hard lot to ingest a pill everyday for the rest of your life, but considering the options - a shot four times a year, a pound of raw liver a day, or neurological deficiencies - maybe it's not so bad. •