Vitamin B-12: How Much Do You Need? health article by Charles R. Attwood, M.D., F.A.A.P.

Isabella, my granddaughter, is now a year old. She has never tasted meat or milk. Still breastfed, her physical growth and development, according to the Denver Developmental Scale, is well above average. She has the smoothest skin I've ever seen–none of the rough areas of eczema usually seen in infants. Isabella also doesn't have ear infections, wheezing, or other respiratory illness seen so often in milk drinkers. Where, her regular pediatrician asks, does she get vitamin B-12? He points out, correctly, that it's only found in animal products.

The answer, for now, is from breast milk. Her mother recently asked me whether or not a supplement will be necessary as she gets older. It's a good question. To begin, let's look at a vegetarian who's passed through adolescence as a vegetarian to see how he dealt with B-12.

Ocean Robbins, of Santa Cruz, California, the 22-year-old son of EarthSave founder John Robbins, has never eaten meat–and for the past 10 years he has consumed no animal products whatsoever. Yet, his physical growth has always been above average and he's rarely been sick. Ocean excelled in both sports and academics throughout his childhood, setting elementary school records for pullups, pushups, and the 10-km run for age 10. He and his father, another famed vegetarian, together recently ran a full marathon. Both take B-12 supplements daily which, Ocean reminds me, don't come from animal sources.

Isabella's Recommended Daily Allowance (RDA) for this vitamin, known to be necessary for cell division and blood formation, is estimated by the National Research Council to be 1 microgram (0.001 mg). The RDA for Ocean should be about 2 micrograms (0.002 mg). Interestingly, however, millions of people worldwide have no known source for this amount of B-12, yet they remain perfectly healthy. So where is it coming from? Are there any plant sources?

The Problem with Seaweed and Soy

Readers of Frances Moore Lappe's Diet for a Small Planet may remember that her first (1971) edition said that certain fermented soy products–such as tempeh, miso, and seaweed–contained vitamin B-12. More recently, however, these sources have been shown to contain only the inactive analogue of the vitamin, which is not metabolized by humans. Ironically, it may actually interfere with the metabolism of active B-12.

The American Academy of Pediatrics' Committee on Nutrition states that deficiencies of vitamin B-12–known chemically as cobalamin–although extremely serious, and which ultimately may lead to irreversible nerve damage, are rarely found among vegetarian children or adults throughout the world. The rural Chinese, for example, some of whom consume only vegetables, fruits, and grains, show no symptoms attributable to deficiencies of this vitamin. So the risk is not great. Personally, during my 34 years as a practicing pediatrician, I have never seen a case of B-12 deficiency. Yet most of my colleagues who advocate a plant-based diet are somewhat cautious and recommend some source of B-12. Dr. Dean Ornish suggests an occasional cup of skim milk. Dr. Neal Barnard recommends taking a multivitamin or B-12 fortified foods.

The most likely explanation for this extreme rarity of B-12 deficiencies among vegans is self-synthesis. Because bacteria from the soil on plants produce the B-12 within the gastrointestinal tracts of animals, it's reasonable to assume that the same may happen when humans eat natural foods. This is more likely if the plants are not carefully cleaned, washed, or overcooked. The Vegetarian Resource Group states that some vegans may get B-12 from inadequate hand washing, but they are quick to point out that this isn't a reliable source. Also, it's been suggested that B-12, like iron, may be absorbed more efficiently by vegans than by people consuming animal products.

Furthermore, a little of this vitamin goes a long, long way. The body can store it for at least five years, maybe longer, so there are virtually always adequate amounts for anyone who occasionally eats meat or dairy products. In fact, there's evidence that vegans who previously ate animal-based food may have vitamin B-12 stores that will not be depleted for 20 to 30 years or more.

Where to Find B-12

In summary, it seems that vegetarians who consume adequate calories face very little chance of developing a B-12 deficiency. But let's face it, parents would like total assurance that they and their children will not be at risk. For them I would suggest a multivitamin containing B-12, a fortified breakfast cereal, fortified soy milk, or fortified meat substitutes. Some forms of nutritional yeast contain adequate amounts of B-12. These non-animal sources are fine; just read the labels. Then you can go ahead and wash your hands.