Dietary Supplements | Natural Health Blog

Date: 03/12/2009    Written by: Jon Barron

Birth Defects From B-12 Deficiency

Vitamin B12, Birth Defects

If you're vegan or vegetarian and you want to procreate, you should know about a new study just published in the journal, Pediatrics. The study found that women who have a vitamin B-12 deficiency stand a greatly increased risk of giving birth to children with severe "neural tube" birth defects. Since B-12 comes primarily from meat, dairy, and fish sources, those who eschew animal foods are particularly at risk.

Neural tube defects involve the brain and spinal cord, causing conditions such as spina bifida, which deforms the spine and backbone and results in paralysis; and anencephaly, a fatal condition that causes underdeveloped brain function. According to the research, those women with the lowest levels of B-12 run up to five times the chance of giving birth to children with neural tube birth defects, compared to women with sufficient stores of the vitamin. Folic acid deficiency also has been linked with natal birth defects, but even when folic acid levels were controlled for, subjects with low B-12 showed elevated risk levels. In other words, both folic acid and B12 levels must be sufficient in order to diminish risk.

While obstetricians these days usually make sure that their pregnant patients take vitamin supplements, according to researcher Dr. James Mills of the National Institutes of Health, "An absolutely critical point is that women have to consider this [need to supplement with vitamin B12] before they become pregnant because once they realize they are pregnant it's likely to be too late." In other words, "cramming" won't work, and since neural tube birth defects tend to occur in the first month of pregnancy, neither will starting the B-12 regimen after conception. Women need to have adequate B-12 both before and after conceiving. Click here for more information on Supplements from Preconception on Up.

In fact, whether or not having babies is on your to-do list, it's essential to ensure that you have an adequate B12 intake. As Dr. Duane Alexander, director of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, said, "Vitamin B12 is essential for the functioning of the nervous system and for the production of red blood cells. The results of this study suggest that women with low levels of B12 not only may risk health problems of their own, but also may increase the chance that their children may be born with a serious birth defect."

Those "health problems of your own" might include pernicious anemia, fatigue, depression, memory loss, psychosis, spinal degeneration, nerve degeneration and irreversible neurological impairment. A study last year at Oxford University found that low levels of B12 in elderly people seemed linked to brain atrophy and shrinkage, which in turn can lead to Alzheimer's. In that study, the subjects who had the lowest B12 levels lost brain volume six times faster than those who had the highest levels of the vitamin. Even more startling, none of the subjects actually showed a B12 deficiency; rather, those with "low levels" were simply in the low-normal range.

Deficiency of vitamin B12 appears common in elderly people, as well as among those with intestinal disorders that lead to poor vitamin absorption (B12 and many other vitamins need a proper cocktail of stomach acid to be absorbed) and, as mentioned before, among vegetarians. According to the Vegetarian Society, while some plant sources do contain significant amounts of B12 -- including spirulina, fermented soy, and seaweed -- the type of B12 in these foods isn't useable by the body. What they contain are B12 analogues (chemical look-alikes) that your body cannot use, and so it's almost impossible for vegans to get enough B12 through diet alone. Vegetarians who eat eggs aren't much better off, because the B12 in eggs also isn't bio-available. Dairy, on the other hand, contains useable B12, but as I've written before, milk products come with a host of other issues, as do many prepared foods fortified with synthetic B12. Nutritional yeast, on the other hand, is a good source of useable vegetarian B12.


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    Submitted by Murray on
    March 15, 2009 - 4:39pm

    Having worked with many Indians who have been strict vegetarians (Hindu) I noticed that many of their children had malformed and displaced teeth. I got to know one couple sufficiently closely to suggest and have them take supplements of B12, B6, D3, Omega 3s and folate before attempting to conceive. The child was born without jaw deformation and is now (7) bigger, longer boned and stronger than his elder brother. They have found similar good things with subsequent children compared to the older siblings born before supplementation.

    Submitted by Tom on
    November 27, 2014 - 11:13am

    Hi Baseline,
    You say "Nutritional yeast, on the other hand, is a good source of useable vegetarian B12".

    One well known Nutritional Yeast product on the internet has B12 added but says:

    "The B12 in this product is an inactive form. It is not Methylcobalamin. If you want proper absorption of B12 then you have to use a supplement".

    What is your opinion on this? Is it a good source of B12? Have they taken out the methylcobalamin and added something like cyanocobalamin?

    Thanks in advance for your help :)

    Submitted by BaselineFoundation on
    November 28, 2014 - 12:24pm

    You are correct. There are no true natural vegetarian sources of B12. If you find B12 in a vegetarian food, it is either a B12 analog (as found in chlorella and spirulina and fermented soy products) or is added as a supplement, usually in the form of cyanocobalmin.Cyanocobalamin is the form of B12 most often sold in vitamin supplements and added to foods. It is a synthetic version of the vitamin and humans cannot directly use it. Instead, the compound must be converted to a usable form through the chemical processes of methylation or adenosylation. Methylcobalamin results from breaking down other cobalamin compounds and attaching a methyl group. The methylated form of B12 is the main form of the vitamin found in human blood plasma and human breast milk. This is the form that Jon recommends for supplementation. Adenosylcobalamin, like, methylcobalamin, results from breaking down other cobalamin compounds, including methyl cobalamin. But instead of picking up a methyl group, a chemical group containing adenosine, 5'-deoxyadenosinyl is attached. Adenosylcobalamin is the primary form of B12 found in non-human animals. In humans, adenosylcobalamin is found mainly in tissues, especially the liver.

    The bottom line is that cyanocobalamin is not necessarily bad as  a supplement, just less efficient than methylcobalamin. Unfortunately, methylcobalamin is almost never added to foods (again, that’s almost always cyanocobalamin), but is available only as a vitamin supplement. So, short answer to your question: B12 is not naturally found in nutritional yeast. It is added as cyanocobalamin.

    Submitted by tom on
    November 29, 2014 - 3:44pm

    Thanks Baseline,
    You went to even more trouble than usual with that answer - much appreciated :)

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