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Women who do not have enough vitamin B12

Women who do not have enough vitamin B12 in their blood before and after conception have a greater chance of having a baby with brain or spinal cord defects, a new study says.

Most at risk may be vegans and vegetarians, since B12 is far more common in meat and animal-based foods, noted an American and Irish research team whose findings were published in the March issue of Pediatrics..

According to the study, women with low levels of B12 had at least 2.5 times the risk of giving birth to a child with these neural tube defects, which can lead to partial paralysis or even death, than women with the highest B12 levels.

"Vitamin B12 is essential for the functioning of the nervous system and for the production of red blood cells," Dr. Duane Alexander, director of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, said in a news release issued by its parent organization, the U.S. National Institutes of Health. "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."

Researchers analyzed blood collected during the early pregnancy stages of hundreds of women from Ireland, a country with a high rate of neural tube defects. Either the women had previously given birth to a baby with a neural tube defect or were known to be carrying babies with the disorder.

Women with B12 concentrations below 250 ng/L before pregnancy had roughly three times the risk of having a child with a neural tube defect as those with higher B12 blood levels. Those women whose levels were less than 150 ng/L, which is considered B12 deficient, had five times the risk of women with higher levels.

The researchers used statistical techniques to focus solely on B12 levels and factor out the role of folic acid, a nutrient known to help prevent pregnant women from birthing babies with neural tube defects. The study authors noted that B12 and folate are jointly linked to several key biochemical reactions, but that a lack of either B12 or folate increased the risk of a neural tube defect.

While confirmation from other studies is needed, the authors suggested women should have vitamin B12 levels above 300 ng/L before becoming pregnant. Study co-author Dr. James L. Mills, a senior investigator in the NICHD division of epidemiology, statistics and prevention research, went further, recommending all women of childbearing age always consume the daily recommended amount of vitamin B12 and at least 400 micrograms of folic acid.

More information

The U.S. Centers for Disease Control and Prevention has more about having a healthy pregnancy.
-- Kevin McKeever

SOURCE: U.S. National Institutes of Health, news release, March 2, 2009
11 Responses
Avatar universal

It seems like there are more people who have vitamin B12 deficiency. I know that CFS patients were found to have normal B12 levels (in their blood), but low B12 levels in their brains.

I purchase and take the B12 drops (available at Walgreens -- Nature's Bounty)
Avatar universal

Vitamin B 12, an essential nutrient, is also known as cobalamin. The cobal in the name refers to the metal cobalt contained in B 12. Vitamin B 12 is required for the normal activity of nerve cells and works with folate and vitamin B 6 to lower blood levels of homocysteine, a chemical in the blood that might contribute to heart disease. B 12 also plays a role in the body's manufacture of S-adenosylmethionine (SAMe).

Anemia is usually (but not always) the first sign of B 12 deficiency. Earlier in this century, doctors coined the name "pernicious anemia" forastubborn form of anemia that didn't improve even when the patient wasgiveniron supplements. Today we know that pernicious anemia comes about whenthestomach fails to excrete a special substance called intrinsic factor.The body needs the intrinsic factor for efficient absorption of vitamin B 12. In 1948, vitamin B 12 was identified as the cure for pernicious anemia. B 12 deficiency also causes nerve damage, and this may, in some cases, occur without anemia first developing.

Vitamin B 12 has also been proposed as a treatment for numerous other conditions, but as yet there is no definitive evidence that it is effective for any purpose other than correcting deficiency.


Extraordinarily small amounts of vitamin B 12 suffice for daily nutritional needs. The official US and Canadian recommendations for daily intake are as follows:

    * Infants
          o 0-6 months: 0.4 mcg
          o 7-12 months: 0.5 mcg
    * Children
          o 1-3 years: 0.9 mcg
          o 4-8 years: 1.2 mcg
          o 9-13 years: 1.8 mcg
    * Males and Females
          o 14 years and older: 2.4 mcg
    * Pregnant Women
          o 2.6 mcg
    * Nursing Women
          o 2.8 mcg

Vitamin B 12 deficiency is rare in the young, but it's not unusual in older people: Probably 10% to 20% of the elderly are deficient in B 12.1-4  This may be because older people have lower levels of stomach acid. The vitamin B 12 in our food comes attached to proteins and must be released by acid in the stomach in order to be absorbed. When stomach acid levels are low, we don't absorb as much vitamin B 12 from our food. Fortunately, vitamin B 12 supplements don't need acid for absorption and should, therefore, get around this problem. However, for reasons that are unclear, one study found that B 12 -deficient seniors need very high dosages of the supplements to normalize their levels, as high as 600 to 1,000 mcg daily.65

Similarly, people who take medications that greatly reduce stomach acid, such as omeprazole (Prilosec) or ranitidine (Zantac) also may have trouble absorbing B 12 from food and could benefit from supplementation.5-10

Stomach surgery and other conditions affecting the digestive tract can also lead to B 12 deficiency. Vitamin B 12 absorption or levels in the blood may also be impaired by colchicine (for gout), metformin and phenformin (for diabetes), and AZT (for AIDS).11,12,69  Exposure to nitrous oxide (such as may be experienced by dentists and dental hygienists) might cause B 12 deficiency, but studies disagree.14,15  Slow-release potassium supplements might impair B 12 absorption as well.17

Vitamin B 12 is found in most animal foods; it is also found only in animal food. Beef, liver, clams, and lamb provide a whopping 80 to 100 mcg of B 12 per 3.5-oz serving, at least 40 times the dietary requirement. Sardines, chicken liver, beef kidney, and calf liver are also good sources, providing between 25 and 60 mcg per serving. Trout, salmon, tuna, eggs, whey, and many cheeses provide at least the recommended daily intake.

Note: Total vegetarians (vegans) must take vitamin B 12 supplements or consume B 12 -fortified foods, or they will eventually become deficient.59,60  Contrary to some reports, seaweed and tempeh do not provide B 12. (Some forms of blue-green algae, such as spirulina, contain B 12, but it is not in an absorbable state.61  )

Vitamin B 12 is available in three forms: cyanocobalamin, hydrocobalamin, and methylcobalamin. The first is the most widely available and least expensive, but some experts think that the other two forms are preferable.

Severe B 12 deficiency can cause anemia and, potentially, nerve damage. The latter may become permanent if the deficiency is not corrected in time. Anemia most often develops first, leading to treatment before permanent nerve damage develops. However, folate supplements can get in the way of this "early warning system." This is why people are cautioned against taking high doses of folate without medical supervision. When taken at a dosage higher than 400 mcg daily, folate can prevent anemia caused by B 12 deficiency, thereby allowing permanent nerve damage to develop without any warning. More mild deficiencies of vitamin B 12 may cause elevated levels of homocysteine in the blood, potentially increasing risk of heart disease. (See the Homocysteine article for more information.) Mild B 12 deficiency (too slight to cause anemia) may also impair brain function.24,25

Avatar universal

Therapeutic Dosages

For correcting absorption problems caused by medications, taking vitamin B 12 at the level of dietary requirements should suffice.

For other purposes, enormously higher daily doses—ranging from 100 to 2,000 mcg—are sometimes recommended.

Therapeutic Uses

It appears that individuals who take medications that dramatically lower stomach acid, such as H2 blockers or proton pump inhibitors, would benefit by taking B 12 supplements.18-23  Other individuals likely to be deficient in B 12, such as the elderly, or those taking the medications listed in Requirements/Sources, might well benefit from a daily B 12 supplement to prevent B 12 deficiency.

For pernicious anemia, B 12 injections are traditionally used but research has shown that oral B 12 works just as well, provided you take enough of it (between 300 and 1,000 mcg daily).26-29

Weak evidence suggests that B 12 supplements may improve sperm activity and sperm count; on this basis, they could be useful for male infertility.30,31  Some cases of recurrent miscarriage might be due to vitamin B 12 deficiency.62

One placebo-controlled, double-blind study, enrolling 49 people with eczema, found benefit with a cream containing vitamin B 12 at a concentration of 0.07%.66  Topical B 12 is hypothesized to work for eczema by reducing local levels of the substance nitric oxide (not related to nitrous oxide).

On the basis of weak and sometimes contradictory evidence, vitamin B 12 has been suggested for HIV,33-37  amyotrophic lateral sclerosis,38  carpal tunnel syndrome,67  diabetic neuropathy,39,40  multiple sclerosis (MS),41-45  restless legs syndrome,46,47  and tinnitus.48

Some evidence suggests that people with vitiligo (splotchy loss of skin pigmentation) might be deficient in vitamin B 12, and supplementation along with folate may be helpful.52,53  However, the evidence is very weak and not all studies agree.54

Some alternative practitioners recommend the use of injected vitamin B 12 for Bell's palsy. However, the only scientific support for this approach comes from one study that was not double-blind.63  (For information on the importance of a double-blind design, see Why Does This Database Rely on Double-blind Studies?)

Vitamin B 12 is also sometimes recommended for numerous other problems, including asthma, depression, osteoporosis, and periodontal disease, but there is essentially no evidence as yet that it really works.

A double-blind trial of vitamin B 12 for seasonal affective disorder (SAD—a type of depression related to lack to lack of light during the winter) failed to find evidence of benefit.58

One double-blind, placebo-controlled study of 140 people with mildly low B 12 levels failed to find the supplement helpful for improving mental function and mood.68

Another study failed to find evidence that vitamin B 12 improved general sense of wellbeing among seniors with signs of mild B 12 deficiency.64

Although vitamin B 12 has been proposed as a treatment for Alzheimer's disease, this recommendation is based solely on the results of one small, poorly designed study.49  More recent and better-designed studies found little to no benefit.50,51,70

What Is the Scientific Evidence for Vitamin B 12 ?

Vitamin B 12 deficiencies in men can lead to reduced sperm counts and lowered sperm mobility. For this reason, B 12 supplements have been tried for improving fertility in men with abnormal sperm production. In one double-blind study of 375 infertile men, supplementation with vitamin B 12 produced no benefits on average in the group as a whole.55  However, in a particular subgroup of men with sufficiently low sperm count and sperm motility, B 12 appeared to be helpful. Such "dredging" of the data is suspect from a scientific point of view, however, and this study cannot be taken as proof of effectiveness.

Safety Issues

Vitamin B 12 appears to be extremely safe. However, in some cases very high doses of the vitamin can cause or worsen acne symptoms.56,57

Interactions You Should Know About

If you are taking:

Colchicine, AZT, medications that reduce stomach acid (such as the H2 blocker ranitidine [Zantac] or the proton pump inhibitor omeprazole [Prilosec], oral hypoglycemics (such as metformin or phenformin), slow-release potassium supplements, or if you are exposed to nitrous oxide anesthesia: You may need extra B 12. Another option is to take extra calcium, which may, in turn, improve B 12 absorption.
Avatar universal
Where did you get the information that the B12 in spirulina or other algaes is not absorbable?  
Avatar universal
  Dagnelie P, van Staveren WA, van den Berg H. Vitamin B-12 from algae appears not to be bioavailable. Am J Clin Nutr. 1991;53:695-697.

   The supplement called spirulina consists of one or more members of a family of blue-green algae. The name was inspired by the spiral shapes in which these plants array themselves as they grow.  Other blue-green algae products are also available on the market, and they are discussed in this article as well.

Spirulina grows in the wild in salty lakes in Mexico and on the African continent. It reproduces quickly, and because the individual plants tend to stick together, it is easy to harvest. Records of the Spanish conquistadors suggest that the Aztecs used spirulina as a food source; we also know that the Kanembu people of Central Africa harvested it from what is now called Lake Chad.

This plant contains high levels of  various B vitamins, beta-carotene, other carotenoids, and minerals, including calcium, iron, magnesium, manganese, potassium, and zinc. It is also a source of gamma-linolenic acid (GLA) . Spirulina is a rich source of protein—dried spirulina contains up to 70% protein by weight—but you'd have to eat an awful lot of spirulina capsules to obtain a significant amount of protein this way. Spirulina also contains vitamin B12, a nutrient otherwise found almost exclusively in animal foods. However, there's a catch: the B 12 in spirulina is not absorbable.

Spirulina has not been proven effective for any medical condition, and there are significant safety concerns involving all forms of blue-green algae (see Safety Issues).
  Spirulina itself appears to be nontoxic.  Studies in rats showed that high spirulina intake caused no weight reduction or toxicity symptoms in rats, nor did spirulina affect the rats' ability to reproduce normally.

Nevertheless, there are areas of serious concern for consumers.

Various forms of blue-green algae can be naturally contaminated with highly toxic substances called microcystins.

Some states, such as Oregon, require producers to strictly limit the concentration of microcystins in blue-green algae products, but the same protections cannot be assumed to have been applied to all products on the market. Furthermore, the maximum safe intake of microcystins is not clear, and it is possible that when blue-green algae is used for a long time, toxic effects might build up. Long-term use by children raises particular concerns, especially in light of the widely popularized, but unsubstantiated belief, that blue-green algae is useful for attention deficit disorder.

Blue-green algae can also contain a different kind of highly toxic substance, called anatoxin.

In addition, when spirulina is grown with the use of fermented animal waste fertilizers, contamination with dangerous bacteria could occur.  There are also concerns that spirulina might concentrate radioactive ions found in its environment.  Probably of most concern is spirulina's ability to absorb and concentrate heavy metals such as lead and mercury if they are present in its environment. One study of spirulina samples grown in a number of locations found them to contain an unacceptably high content of these toxic metals.  However, a second study on this topic claims that the first used an unreliable method of analyzing heavy metal content,  and concludes that a person would have to eat more than 77g daily of the most heavily contaminated spirulina to reach unsafe mercury and lead consumption levels.

These researchers, however, go on to suggest that it is not prudent to eat more than 50 g of spirulina daily. The reason they give is that the plant contains a high concentration of nucleic acids, substances related to DNA. When these are metabolized, they create uric acid, which could cause gout or kidney stones. This is of special concern to those who have already had uric acid stones or attacks of gout.

The safety of spirulina in pregnant and nursing women, young children, and individuals with kidney or liver disease has not been determined.
Avatar universal
I think you're confusing two different types of blue green algae.  The contaminated algae wasn't spirulina, it was something called Klamath Falls blue green algae, and it happened several years ago.  It was made by one multi-level traded company.  It's harvested only in Oregon.  All the spirulina grown for sale in health food stores is from Hawaii and California, with the cleanest being that grown in Hawaii.  And as for fermented fertilizer, hate to tell you but that's what compost is, all organic agriculture and most commercial agriculture uses it.  If it's done correctly, no problem; if it isn't, big problem.  The main fertilizer forever has been composted manure.  It's an art form and a skill, like any other, and if done correctly, well, we're still here, right?  And it's a lot safer than synthetic fertilizer, which is a petroleum product.  

If you're going to avoid foods that are potentially toxic, stop eating.  There aren't any foods that aren't potentially toxic.  And I've still never heard that the B12 in spirulina isn't absorbable, but you've cited a study so I'll have to consider that it might be.  Still, a lot of people have eaten it for at least hundreds of years, probably thousands, so it seems to have stood the test of time, and I know a lot of vegetarians who were quite healthy and not B12 anemic who were getting their B12 from algae.  All blue green algae is is fresh water seaweed, and yes, all algae can soak up toxins, but they also do that in the body, which is a good thing.  Like natural chelation.  Spirulina is a front line treatment for radiation poisoning, for example.  

It's all complicated.  Fish is full of toxins, but people who eat it are healthier than people who aren't.  Seaweed is full of toxins, but the Japanese, who eat the most of it, live longer than anyone on Earth.  Don't let perfection be the enemy of the good, as they say.
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