Vitamin B12 (cobalamin) is an important nutrient. It’s one of a group of substances called essential nutrients, meaning that in order to get enough B12, you have to eat foods that have the vitamin in them. It is needed to produce red blood cells and effects the functioning of the brain and nervous system; B12 deficiency can lead to anemia and dementia.
Although the body doesn’t make B12, it can convert any of the several forms into the kinds it needs. Vitamin B12 is found in fish and shellfish, meat, eggs, and dairy products. In the United States, synthetic B12 is often added to livestock feed, making farmed meat an especially good source.
Vegetarians, and particularly vegans, typically need additional B12. A compound found in soy products can reduce B12 levels by, in effect, mimicking B12 despite not being useable by the body, thus distracting the B12 utilization mechanisms.
Some medical conditions also cause people to need B12 supplements because they interfere with absorption. The drug metformin needs to be taken with supplemental B12. People infected with HIV have trouble with absorption. Patients who have gastrointestinal illness or have had intestinal surgery may be prone to B12 deficiency. Interestingly, insufficient B12 can both cause and result from anemia.
Because B12 is so important in building and maintaining brain tissue, it is necessary for everyone to get it in order to keep up cognitive functioning. Although getting enough—or more than enough—B12 has not been shown to improve memory or cognition in people who don’t have problems in those areas, it can help prevent such problems, or even slow degeneration in dementia and Alzheimer’s if they do occur.
Unfortunately, according to a Tufts University study, more than half of Americans are deficient in B12. It’s an easy condition to correct if you recognize it, however. Symptoms include weakness and tiredness, unusual pallor, rapid heartbeat, bleeding gums, stomach upset, and a sore tongue. An oral overdose of B12 is non-toxic, so if you’re experiencing these symptoms, it’s probably safe to take oral or sublingual supplements, but you ought to consult a doctor.