This week’s nutrient is vitamin B12 also known as cobalamin, methylcobalamin (the most active form in the human body), cyanocobalamin (the synthetic form used in supplements), hydroxocobalamin, and adenosylcobalamin.

B12 is one of my favorites, for several reasons.

First, B12 is the most structurally complicated vitamin, and cannot be produced by any plant or animal, but rather only by microorganisms. Probably the biggest claim to fame of vitamin B12 is that it relieves fatigue.

That’s true, but B12 does so much more for us. Here are more vitamin B12 benefits:

1. Vitamin B12 acts as a detoxifying agent, particularly when used in the form of methylcobalamin. The power lies in the “methly” part of methlycobalamin. B12 can help the body detoxify substances such as arsenic, mercury, glutamates from artificial sweeteners, monosodium glutamate (msg), mycotoxins, andcyanide.

2. Cobalamin protects and repairs the nervous system. Studies show that a deficiency in B12 can lead to such nerve problems as peripheral neuropathy, mental changes, multiple sclerosis and neural tube birth defects. This vitamin even helps problems not associated with B12 deficiency such as Bell’s palsy, and atrophic lateral sclerosis (Lou Gherig’s disease). B12 actually bathes nerves to help regenerate lost myelin, which is a fatty substance that surrounds and protects nerves.

3. B12 boosts energy by helping us use the food we eat. It’s also necessary for synthesizing DNA, building red blood cells and assisting with metabolic function.

Unlike other B vitamins, B12 deficiency is fairly common. One of the first signs of B12 deficiency is fatigue and confusion. Other symptoms include pale or jaundiced skin, sensations of pins and needles, mouth ulcers, dizziness, mood changes and vision problems.

Those at risk of vitamin B12 deficiency are the elderly, folks using the diabetes drug “metformin”, individuals who’ve had surgery to remove part of the bowel that absorbs B12, and those taking long term antacid drugs for heartburn (since stomach acid is needed for the absorption of B12). Vegetarians and vegans are at particular risk, because B12 is an animal-based nutrient, and cannot be derived from plant sources.

I recommend vegetarians include at least one vitamin B12 source a day from eggs or dairy, and vegans take a B12 supplement or consume vitamin B12 fortified foods. Other food sources include beef liver, tuna, trout, salmon and chicken.

Daily allowances for vitamin B12 are birth to 6 months: 0.4 mcg; infants 7-12 months: 0.5 mcg; children 1-3 years: 0.9 mcg; children 4-8 years: 1.2 mcg; children 9-13 years: 1.8 mcg; teens 14-18 years: 2.4 mcg; adults: 2.4 mcg; pregnant teens and women: 2.6 mcg; breastfeeding teens and women: 2.8 mcg.

While these are the United States Recommended Daily Allowances for vitamin B12, I suggest higher allowances or doses, of 1,000 to 2,500 mcg. Because B12 does not easily absorb in the GI tract, I recommend either sublingual (under the tongue) supplements or B12 injections.

Also, as with all B vitamins, they should be in your system  at the same time, so when taking B12, make sure you’ve taken your B complex.

Diet or exercise question? David Crocker, of Landrum, has been a nutritionist and master personal trainer for 30 years.