B12 overdose / megadose?

[veganwitch]

Hi Korn,
As usual, you make a lot of sense. It's so true how ill/sick vegans are often thought to be that way b/c they are vegan, while omnis are just unwell. I'm going to check out that thread you recommended and tackle the healthier eating. Much thanks :)

[onfiregirl]

i have a big question, and need a quick reply ,

is it possible for a b12 levels of twins 63 and 93 with injections and chewable suppliments to over a 1118 in less then 5 months , then 4 months after that be down to levels of 383 and 524 with incontinued suppliments? keep in mind that the twins are my daughters and are 11 years old .

[Michael Benis]

Don't take a risk. Go back to supplementation for a period and get the levels measured again (a) as soon as possible (b) after a few weeks or so.

Find a sympathetic doctor and/or qualified nutritionist enlist their support to follow this.

[onfiregirl]

i wish i could , but my kids are temp in foster care due to the low levels of b12 .

[Korn]

i have a big question, and need a quick reply ,

is it possible for a b12 levels of twins 63 and 93 with injections and chewable suppliments to over a 1118 in less then 5 months , then 4 months after that be down to levels of 383 and 524 with incontinued suppliments? keep in mind that the twins are my daughters and are 11 years old .
Loads of stuff affect your children's B12 levels... and regarding B12 injections, have you seen this thread: Is oral B12 as effective as intramuscular injections? (http://www.veganforum.com/forums/showthread.php?t=9391)

ANyway, if you look around, I believe we have a thread here which describes how much someone's B12 levels will decrease if they don't have any B12 intake at all under normal circumstances.

[onfiregirl]

Loads of stuff affect your children's B12 levels... and regarding B12 injections, have you seen this thread: Is oral B12 as effective as intramuscular injections? (http://www.veganforum.com/forums/showthread.php?t=9391)

ANyway, if you look around, I believe we have a thread here which describes how much someone's B12 levels will decrease if they don't have any B12 intake at all under normal circumstances.

wow thank you , now i wish i had ink for my printer.

[Michael Benis]

i wish i could , but my kids are temp in foster care due to the low levels of b12 .

Wow! Very sorry to hear that. Try not to fight the "health" people with this, since this is likely to make things worse. Find out what supplements they are giving your daughters (and then on your own whether they're vegan - one step at a time). As these people for their advice., Then do your won research on how you can follow it so as to ensure you get your daughters back as soon as possible.

Best wishes.

And remember two and three and four heads (etc.) are better than one: you will get lots of support here.

Cheers

MIke

[onfiregirl]

Loads of stuff affect your children's B12 levels... and regarding B12 injections, have you seen this thread: Is oral B12 as effective as intramuscular injections? (http://www.veganforum.com/forums/showthread.php?t=9391)

ANyway, if you look around, I believe we have a thread here which describes how much someone's B12 levels will decrease if they don't have any B12 intake at all under normal circumstances.
im sorry if i sound lame but where exactly is that thread, i cant seam to find it ?

[Korn]

i wish i could , but my kids are temp in foster care due to the low levels of b12 .

This sounds horrible, wrong and strange. 39% of non-vegans have low B12 levels, according to one of the largest B12 studies out there, and 9% of them are B12 deficient according to the same study. One doesn't put a child in foster care for low vitamin levels, one gives them vitamins.

Plus: knowing about all those nutrients meat eaters normally are deficient in, taking a vitamin deficient child away from their parents is not only completely crazy, it's of course also totally impossible. Have a look at this thread: Nutrient deficiencies more common in meat eaters than in vegans? (http://www.veganforum.com/forums/showthread.php?t=24)
If a child (vegan or not) would have been taken away from their parents after finding that the child had a nutrient deficiency (which apparently 99% of all people have), I'd personally find a good lawyer and sue them.

[onfiregirl]

This sounds horrible, wrong and strange. 39% of non-vegans have low B12 levels, according to one of the largest B12 studies out there, and 9% of them are B12 deficient according to the same study. One doesn't put a child in foster care for low vitamin levels, one gives them vitamins.

Plus: knowing about all those nutrients meat eaters normally are deficient in, taking a vitamin deficient child away from their parents is not only completely crazy, it's of course also totally impossible. Have a look at this thread: Nutrient deficiencies more common in meat eaters than in vegans? (http://www.veganforum.com/forums/showthread.php?t=24)
If a child (vegan or not) would have been taken away from their parents after finding that the child had a nutrient deficiency (which apparently 99% of all people have), I'd personally find a good lawyer and sue them.
im working on that , plus my appeal is on monday ,

my worker has been trying to say that my daughters ADHD WAS CAUSED BY THE LOW B12 but id like to point out that now both girls b12 levels are over 1000 from the low levels of 63 and 93 . and both are experiancing overdose systems, as to swelling of the neck and hands essy the yungest twin has been complaining about being itchy all the time since first taking the injections .

[Korn]

im sorry if i sound lame but where exactly is that thread, i cant seam to find it ?

There's some info here http://www.rawbc.org/articles/B12.html:



To understand the significance of this issue, we need to understand a little about the importance of B-12 in the diet. The average non-vegetarian stores between 2,000 and 3,000 picograms (pg., same as micrograms) of B-12 and loses about 3 pg. per day. About 60 percent of the total amount of the B-12 in the body is stored in the liver and 30 percent is stored in the muscle. The body has a special circulation pattern between the digestive tract and the liver. Through the bile, we secrete 1.4 pg. per day of B-12 into the small intestine, and healthy people reabsorb about 0.7 pg. Research suggests that if people have a low B-12 intake, the absorption increases to even draw more B-12 into the system. However, there is still a general potential for slow loss, depending on the variation in this special, what is known as enterohepatic circulation, before we develop the potential of B-12 deficiency symptoms.


The good news that one major study in the United Kingdom in 1988 showed, in studying 37 vegan children was that there was normal growth and development in children who were breastfed for 6 months at a minimum, when there was B-12 supplementation.

Young childrenand teenage children who were supplemented with B-12 were found to grow normally. Adults who were vegetarian without B-12 supplementation for greater than six years usually had a lower B-12 than non-vegetarian adults in the general research. In one study of adults in 1994, 81% of the vegan adults had a B-12 lower than 200 pg. That is approximately the percentage of adults on a live food diet who are low in B-12. In my clinical experience, meat eaters, vegans and live-fooders tend to have a fairly high percentage of B-12 deficiency, although meat eaters do have less incidence. My experience is that cooked food vegans have a higher incidence of B-12 deficiency than live fooders, but there is still a significant occurance in live fooders. In vegetarians and vegans, there is also a high percentage under 200 pg., about 54%. A study in 1982 by Dunn and Scott of raw food vegans with 83 subjects from the Natural Hygiene Society showed that 92% of the vegans had a B-12 less than 200 pg., and in 53% it was less than 100 pg. The World Health Organization (WHO) considers B-12 deficiency to be less than 200 pg. The percentages of B-12 deficiency tend to increase over time on a natural hygiene diet. Another study in Finland in 1995 that examined B-12 status of long-term 100% raw vegans found that 66% of the people had a B-12 lower than 200 pg. One study done in 2000 by Donaldson at Hallelujah Acres on primarily live food diet people, but with some B-12 supplementation via nutritional yeast, showed only about 15% of the people were less than 200, and none of them less than 160. The supplementation with nutritional yeast was 5 pg. of B-12 from one tablespoon of Red Star Vegetarian Support.





...and here:

http://en.wikipedia.org/wiki/Vitamin_B12

The total amount of vitamin B12 stored in body is about 2,000-5,000 mcg in adults. Around 50% of this is stored in the liver.[23] Approximately 0.1% of this is lost per day by secretions into the gut as not all these secretions are reabsorbed. Bile is the main form of B12 excretion, however, most of the B12 that is secreted in the bile is recycled via enterohepatic circulation.[24] Due to the extremely efficient enterohepatic circulation of B12, the liver can store several years’ worth of vitamin B12; therefore, nutritional deficiency of this vitamin is rare. How fast B12 levels change depends on the balance between how much B12 is obtained from the diet, how much is secreted and how much is absorbed. B12 deficiency may arise in a year if initial stores are low and genetic factors unfavourable or may not appear for decades. In infants, B12 deficiency can appear much more quickly.


There's also something here (...and here http://www.living-foods.com/articles/b12issue.html).

And here's a thread discussing various doctors and nutritionist that recommend a vegan diet. (http://www.veganforum.com/forums/showthread.php?t=25185&highlight=doctors)

This one is also useful:
American Dietetic Association and Dietitians of Canada: Vegetarian/Vegan Diets (http://www.veganforum.com/forums/showthread.php?t=22615):


This position paper reviews the current scientific data related to key nutrients for vegetarians, including protein, iron, zinc, calcium, vitamin D, riboflavin, vitamin B-12, vitamin A, n-3 fatty acids, and iodine.

A vegetarian, including vegan, diet can meet current recommendations for all of these nutrients. In
some cases, use of fortified foods or supplements can be helpful in meeting recommendations for individual nutrients.

Well-planned vegan and other types of vegetarian diets are appropriate for all stages of the life cycle, including during pregnancy, lactation, infancy, childhood, and adolescence.

Vegetarian diets offer a number of nutritional benefits, including lower levels of saturated fat, cholesterol, and animal protein as well as higher levels of carbohydrates, fiber, magnesium, potassium, folate, and antioxidants such as vitamins C and E and phytochemicals. Vegetarians have been reported to have lower body mass indices than nonvegetarians, as well as lower rates of death from ischemic heart disease; vegetarians also show lower blood cholesterol levels; lower blood pressure; and lower rates of hypertension, type 2 diabetes, and prostate and colon cancer.

[onfiregirl]

There's some info here http://www.rawbc.org/articles/B12.html:

thank you for the information , i found a doc who in new zealand and emailed her .







...and here:

http://en.wikipedia.org/wiki/Vitamin_B12



There's also something here (http://...and%20here%20http://www.living-foods.com/articles/b12issue.html).

And here's a thread discussing various doctors and nutritionist that recommend a vegan diet. (http://www.veganforum.com/forums/showthread.php?t=25185&highlight=doctors)

This one is also useful:
American Dietetic Association and Dietitians of Canada: Vegetarian/Vegan Diets (http://www.veganforum.com/forums/showthread.php?t=22615):

[Korn]

For those who haven't read all the 100+ posts in the thread, here are some more or less random excerpts of the topics that are being discussed in this thread:

Too much brewers yeast can impair the kidney function (+ cause fungus issues)
People with high B12 levels tend to frequently suffer from tachycardia, panic-anxiety attacks, or angina-like chest pains, that may be accompanied by numbness and tingling in the face or extremities.
Animals studies show that there have been cases of increased cancer production in animals receiving high levels of B-12 (the animals have an increased production of white blood cells such as occurs in chronic myelogenous leukemia).
A case has been reported of acute myeloblastic leukemia resulting from B-12 overdose in the treatment of pernicious anemia.
A group of French investigators reported a series of cases suggesting that B-12 may stimulate multiplication of cancer cell division in general and certain tumor cells in particular.
Patients with rheumatoid arthritis present serum B-12 levels significantly higher than normal subjects.
B12 is also known to be higher in patients with ulcerative colitis, and other serious illnesses.
A high serum B-12 level should be a signal for a thorough medical evaluation.


I'm not in any way advocating that vegans on a varied diet always are safe without taking supplements of any kind (including no B12). I feel I need to post clarifications about this every now and then, since a few people have read some of my B12 writings and assume that I subscribe to the viewpoints that some vegans did, especially a few decades ago – namely that vegans never needed any supplements, including B12, and that one would be OK (B12 wise) if one was eating some more or less random seaweed/tempeh/miso products or didn't wash the plants one was eating.

The purpose of this thread is only to put some focus on the fact that too much B12 isn't good either, which also could be the problem with the many diseases that are more widespread among meat eaters than veg*ns - since one of the main differences between meat eaters and veg*ns, nutrient wise, is the differences in the B12 intake.

B12 needs some extra attention, but the myth that there are no risks involved with taking high amounts of B12 needs some attention IMO. It is, for example, important when giving supplements to children.

I created a new subforum yesterday, collecting a lot of threads dealing with health issues related to consumption of animal products.

It's called Animal products & health (http://www.veganforum.com/forums/forumdisplay.php?f=139)

[Korn]

From http://www.cancerresearchuk.org/aboutcancer/reducingyourrisk/diet
Eating lots of red or processed meat is a risk factor for bowel cancer. There is also some evidence that breast, lung, prostate and pancreatic cancers are linked to a diet high in red or processed meat.
(I know there is some controversy about breast cancer/meat link. Korn).
Commenting this post from 2005, there's now new, related findings about B12 and (mainly lung) cancer:

Here's the abstract:
http://jama.ama-assn.org/cgi/content/short/302/19/2119



Results During study treatment, median serum folate concentration increased more than 6-fold among participants given folic acid. After a median 39 months of treatment and an additional 38 months of posttrial observational follow-up, 341 participants (10.0%) who received folic acid plus vitamin B12 vs 288 participants (8.4%) who did not receive such treatment were diagnosed with cancer (hazard ratio [HR], 1.21; 95% confidence interval [CI], 1.03-1.41; P = .02). A total of 136 (4.0%) who received folic acid plus vitamin B12 vs 100 (2.9%) who did not receive such treatment died from cancer (HR, 1.38; 95% CI, 1.07-1.79; P = .01). A total of 548 patients (16.1%) who received folic acid plus vitamin B12 vs 473 (13.8%) who did not receive such treatment died from any cause (HR, 1.18; 95% CI, 1.04-1.33; P = .01). Results were mainly driven by increased lung cancer incidence in participants who received folic acid plus vitamin B12. Vitamin B6 treatment was not associated with any significant effects.

Conclusion: Treatment with folic acid plus vitamin B12 was associated with increased cancer outcomes and all-cause mortality in patients with ischemic heart disease in Norway, where there is no folic acid fortification of foods.

The study is discussed here: Treatment With Folic Acid, Vitamin B12 Associated With Increased Risk of Cancer, Death (http://www.sciencedaily.com/releases/2009/11/091117161013.htm)

[Korn]

High Doses of B Vitamins Associated With Increased Decline in Kidney Function for Patients With Kidney Disease from Diabetes (http://www.sciencedaily.com/releases/2010/04/100427171752.htm)


According to background information in the article, several observational studies have shown a significant association between high concentrations of plasma total homocysteine and the risk of developing diabetic nephropathy, retinopathy, and vascular diseases, including myocardial infarction (MI; heart attack) and stroke. B-vitamin therapy (folic acid, vitamin B6, and vitamin B12) has been shown to lower the plasma concentration of homocysteine.
Andrew A. House, M.D., of the University of Western Ontario, and J. David Spence, M.D., of the Robarts Research Institute, London, Ontario, and colleagues conducted a study to examine whether B-vitamin therapy would slow the progression of diabetic nephropathy and prevent vascular events in 238 patients with type 1 or 2 diabetes. The randomized, placebo-controlled trial was conducted at five university medical centers in Canada between May 2001 and July 2007. Patients received single tablet of B vitamins containing folic acid (2.5 mg/d), vitamin B6 (25 mg/d), and vitamin B12 (1 mg/d), or matching placebo. The primary outcome was change in radionuclide glomerular filtration rate (GFR; a measure of kidney function) between baseline and 36 months. Other outcomes included dialysis and a composite of heart attack, stroke, revascularization and all-cause death. Plasma total homocysteine was measured. Participants were followed-up for an average of 31.9 months.
Among the results, the researchers found that participants assigned to the B-vitamin group had a greater decrease in radionuclide GFR (and subsequently poorer kidney function) compared with the placebo group. Also, participants randomized to receive B vitamins had a significantly greater number of cardiovascular and cerebrovascular events, with the 36-month risk of a composite outcome, including heart attack, stroke, revascularization, and all-cause mortality that was double in the B-vitamin group, compared to the placebo group. There was no difference in requirement of dialysis.
Regarding plasma total homocysteine levels, at 36 months, participants in the B-vitamin group had an average decrease while participants in the placebo group had an average increase.
"Given the recent large-scale clinical trials showing no treatment benefit, and our trial demonstrating harm, it would be prudent to discourage the use of high-dose B vitamins as a homocysteine-lowering strategy outside the framework of properly conducted clinical research," the authors conclude.

[Korn]

Heart disease: B-Vitamin Pills Have No Effect, Review Finds (http://www.sciencedaily.com/releases/2009/10/091006191312.htm)



Certain B-vitamins, specifically B12, B9 (folic acid) and B6, influence levels of an amino acid in the blood called homocysteine. High levels of this molecule are associated with an increased risk of heart disease. It has been suggested that giving B-vitamin supplements could help regulate levels of homocysteine, thereby reducing the risk of cardiovascular disease and death. But according to the researchers, there is no scientific basis for this claim.
The review included eight trials involving a total of 24,210 people. None of the eight trials individually supported the idea that giving B-vitamin supplements could prevent cardiovascular disease. Together the data show that B-vitamin supplements, whether compared with placebos or standard care, have no effect on the incidence of heart attack, stroke or death associated with heart disease.
"Prescription of these supplements cannot be justified, unless new evidence from large high quality trials alters our conclusions. There are currently three ongoing trials that will help to consolidate or challenge these findings," says Martí-Carvajal.

[patientia]

They should have separated their variables.

[Korn]

They should have separated their variables.
Sure.


When possible side effects of high B12 intake are discussed, they often focused on allergic reactions. Cancer isn't usually seen as an allergic reaction, but this (http://jama.ama-assn.org/cgi/content/short/302/19/2119) study shows that treatment with folic acid plus vitamin B12 was associated with increased cancer outcomes and all-cause mortality in patients with ischemic heart disease.

I'll post a summary of this thread later, listing the various findings about high B12 intake that has been quoted in the many posts here.

[Korn]

There's some info about B12 side effects and benefits here:
http://www.bodybuildingforyou.com/vitamins-minerals/vitamin-b12-cobalamin-benefit.html

From http://en.wikipedia.org/wiki/Vitamin_B12#Side_effects.2C_contraindications.2C_a nd_warnings.




Side effects, contraindications, and warnings
Vitamin B12 has extremely low toxicity and even taking it in enormous doses appears not to be harmful to healthy individuals.[43][44]
Hematologic: Peripheral vascular thrombosis has been reported. Treatment of vitamin B12 deficiency can unmask polycythemia vera, which is characterized by an increase in blood volume and the number of red blood cells. The correction of megaloblastic anemia with vitamin B12 can result in fatal hypokalemia and gout in susceptible individuals, and it can obscure folate deficiency in megaloblastic anemia. Caution is warranted.
Leber's disease: Vitamin B12 in the form of cyanocobalamin is contraindicated in early Leber's disease, which is hereditary optic nerve atrophy. Cyanocobalamin can cause severe and swift optic atrophy, but other forms of vitamin B12 are available.[citation needed] However, the sources of this statement are not clear, while an opposing view[45] concludes: "The clinical picture of optic neuropathy associated with vitamin B12 deficiency shows similarity to that of Leber's disease optic neuropathy. Both involve the nerve fibres of the papillomacular bundle. The present case reports suggest that optic neuropathy in patients carrying a primary LHON mtDNA mutation may be precipitated by vitamin B12 deficiency. Therefore, known carriers should take care to have an adequate dietary intake of vitamin B12 and malabsorption syndromes like those occurring in familial pernicious anaemia or after gastric surgery should be excluded."

From http://vitamins.lovetoknow.com/Vitamin_B_12_Side_Effects:

Vitamin B 12 Side Effects
Experiencing vitamin B 12 side effects can be rare; however, they do occur. Vitamin B 12 delivered through tablets or sublingual supplements will have fewer potential side effects than vitamin B 12 injections. The following side effects have been noted in both oral supplementation and injections of vitamin B12 unless otherwise noted. The most common side effects of vitamin B 12 supplementation include:

Allergic reactions to preservatives in the preparation for the injection
Mild diarrhea
Anxiety
Panic attacks
Heart palpitations
Insomnia
Breathing problems
Chest pain
Rash and/or hives
Itchy skin
Heartburn
Vomiting
Back pain
Rhinitis (stuffy nose)
In extremely rare cases, the following side effects have been noted:

Congestive heart failure
Pulmonary edema
Peripheral vascular thrombosis (blood clots in the arms and legs)
Folliculitis
Inflammatory acne
Anaphylaxis (most likely related to preservatives used in vitamin B 12 injections)
Because vitamin B 12 is a water soluble supplement, oral supplementation can often lead to bright yellow, strongly scented urine. This is a very common occurrence. Risks of side effects increase with dosage and method of delivery, with vitamin B12 injections having the highest incidence of reported severe side effects and oral supplementation having the lowest incidence of reported side effects, which were mostly mild and transitory.


And, from the same site, about side effects of B12 injections (http://vitamins.lovetoknow.com/Vitamin_B12_Injections_Side_Effects):

Common Side Effects of Injections of Vitamin B12
There are many side effects that patients may experience from injections of vitamin B12. The more common side effects include:

Mild diarrhea
Upset stomach
Nausea
A feeling of pain and a warm sensation at the site of the injection
A feeling, or a sense, of being swollen over the entire body
Headache
Joint pain
If any of these side effects become severe or troublesome, let your doctor know right away.

Vitamin B12 Injections: Side Effects That are Uncommon and Serious
Vitamin B12 injections can result in serious side effects. Although this is a relatively rare occurrence, anyone taking vitamin B12 injections should be aware of the possibility. Call your doctor immediately if you experience any of the following side effects.

A rapid heartbeat
Heart palpitations
Chest pain
A feeling of tightness in the chest
Rapid weight gain
Muscle weakness
Muscle pain
Muscle cramps
A feeling of extreme thirst
Frequent urination
Leg pain
A sense of confusion
Numbness
Dizziness
A tingling sensation
Difficulty breathing
Difficulty swallowing
Shortness of breath with mild exertion or when lying down
Unusual coughing
Unusual wheezing
A feeling of extreme tiredness or fatigue
Swelling of the extremities including hands, arms, lower legs, feet or ankles
Redness, pain or a feeling of warmth in one leg
Tenderness or swelling in one leg
A red skin color on the face
A red skin color anywhere on the body
Hives
Itching
Skin rash
Other vitamin B12 injections side effects may also occur. If you experience anything unusual while taking B12 injections let your doctor know as soon as possible.



From http://ezinearticles.com/?The-Side-Effects-Of-Vitamin-B12&id=816035

Side Effects

The good news is that vitamin B 12 is usually non-toxic, even when taken in large doses. However, people have experienced some adverse effects, even though these side effects are quite rare. Generally, when vitamin B12 supplements are taken orally then there is little chance of side effects occurring. Some people choose to take vitamin B12 administered with an injection. This type of ingestion as been associated with the following side effects:

o mild diarrhoea

o anxiety and panic attacks

o heart palpitations

o insomnia

o breathing problems

o chest pain

o skin rash, hives or itchy swollen skin

Some health professionals believe that patients develop these reactions not because of the B12, but because of the preservatives that are part of the injection formula. Currently, most injections contain preservatives. To be on the safe side, it is probably better to take B12 orally.

Medical Conditions

Other side effects may be experienced by people who have an allergy or a sensitive to cobalamin and cobalt. If this is the case, then it is advisable to avoid vitamin B12 supplementation altogether and instead seek to eat the foods that contain naturally occurring B12. In addition B12 should be avoided by people suffering from Leber's disease, a hereditary disease in which the optic nerve wastes away. Ingesting vitamin B12 can actually speed up the atrophy of the optic nerve resulting in rapid loss of central vision.

There is also evidence to suggest that patients who have undergone heart surgery and received coronary stents may have an increased risk of the artery narrowing again when they take vitamin B12. A small risk, but one to bear in mind.

On a positive note, pregnant and breastfeeding women can take vitamin B12 quite confidently when it is taken orally in amounts not exceeding the recommended daily allowance (2.6 mcg/day if pregnant and 2.8 mcg/day if breastfeeding)

As can be seen, vitamin B12 is a relatively safe vitamin with very few adverse side effects even when taken in large doses. More problems than not arise from B12 deficiency than they do from ingestion of the vitamin itself.

From http://www.drugs.com/sfx/vitamin-b12-side-effects.html:


Cardiovascular

Cardiovascular side effects associated with parenteral cyanocobalamin have included congestive heart failure, pulmonary edema, and peripheral vascular thrombosis. These effects were usually reported early in treatment.

Dermatologic

Dermatologic side effects associated with both intranasal and parenteral cyanocobalamin have included itching and transitory exanthema.

Dermatologic side effects have rarely included exacerbation or onset of inflammatory acne and folliculitis related to B12.

Exacerbation or onset of inflammatory acne and folliculitis have been seen with high doses of B12 (5 to 10 mg/week). The etiology and pathogenic mechanisms of vitamin B12-induced acne are unknown. When present, acneiform eruptions usually occur on the facial area after the first or second injection, and typically disappear within 8 to 10 days after stopping therapy.

A single case of a severe skin eruption resembling acne rosacea that was temporally associated with daily ingestion of 100 mcg of B12 (with 100 mg of B6) has been reported. The rash resolved upon discontinuation of both drugs and recurred upon rechallenge with half the doses.

Some have suspected sorbitol or iodine that is present in some ampules of B12 may be the cause of at least some cases of skin eruptions associated with this drug.

Gastrointestinal

A single case of cecal vitamin B12 bezoar has been reported in an elderly man with a history of multiple gastrointestinal surgeries.

Gastrointestinal side effects associated with parenteral cyanocobalamin have included dyspepsia, nausea, vomiting, and mild transient diarrhea.

Gastrointestinal side effects associated with intranasal cyanocobalamin have included glossitis and nausea.

Hypersensitivity

Anaphylactic reactions have been reported primarily with parenteral administration of B12 and are thought to be the result of impurities of B12 preparations that are no longer manufactured. They may occur soon after a sensitizing dose, within a few weeks or months, or rarely after a latency of several years.

Hypersensitivity side effects associated with parenteral cyanocobalamin have rarely included anaphylactic reactions and death.

Nervous system

Nervous system side effects associated with parenteral cyanocobalamin have included abnormal gait, asthenia, anxiety, dizziness, hypoesthesia, incoordination, nervousness, and incoordination.

Nervous system side effects associated with both parenteral and intranasal cyanocobalamin have included paresthesia and headache.

Hematologic

Hematologic side effects have included polycythemia vera.

Musculoskeletal

Musculoskeletal side effects associated with parenteral cyanocobalamin have included arthritis, back pain, and myalgia.

Respiratory

Respiratory side effects associated with parenteral cyanocobalamin have included dyspnea.

Respiratory side effects associated with both parenteral and intranasal cyanocobalamin have included rhinitis.

Immunologic

Immunologic side effects associated with both parenteral and intranasal cyanocobalamin have included infection.

Other

Other side effects associated with parenteral administration of cyanocobalamin have included feeling of swelling of entire body, back pain, and generalized pain.



Read more: http://www.drugs.com/sfx/vitamin-b12-side-effects.html#ixzz0tdWZ7SOg

[Korn]

Panic like symptoms have been mentioned earlier in this thread, as a potential side effect of a B12 megadose. While panic attacks may be a rare side effect, they are still 'interesting', since their existence maybe will shed some light (in the future) about what too much B12 can do. Now, being worried about too much B12 isn't something someone on a vegan diet need to worry about as such, but if one should follow some of the recommendations from some "B12 fanatics" about taking 1000 mcg daily, it's definitely relevant to look at what high amounts of B12 can do to us.

Here's (http://www.acu-cell.com/diet.html) some relevant info:


Weight Loss Clinics

In addition to their proprietary weight-reducing programs, some weight loss clinics also provide clients with
Vitamin B12 and/or Vitamin B6 injections. For most people, extra Vitamin B12 improves energy, well-being,
and it supports thyroid functions, however some individuals already exhibit above-normal Vitamin B12 levels,
and of those, a small percentage experiences panic anxiety-like symptoms following a Vitamin B12 shot, or
a worsening of Mitral Valve Prolapse (MVP) symptoms (which are rarely attributed to B12 injections), so this
should be kept in mind if those symptoms are experienced.

Vitamin B6 can help with weight loss through a stimulating effect on the thyroid as well, which - by boosting
the right cardiac output, reduces water retention, hence the diuretic attributes. In those with a disposition for
hypoglycemia (low blood sugar), higher doses of Vitamin B6 & higher doses of Vitamin C are not advisable
since they can trigger erratic blood sugar changes and depressive mood swings.

Larger doses of Vitamin B6 will also result in a high Magnesium / low Calcium Ratio, so if not matched to
a patient's requirements (which can happen when Vitamin B6 + Vitamin B12 injections are regularly given at
weight loss clinics), a severe calcium deficiency develops. This by itself - or when aggravated by an over-
stimulated thyroid from the regular Vitamin B6 / B12 shots - can result in insomnia, anxieties, mood swings,
chest pains, depression, joint pains, muscle cramps, or other symptoms.

[Korn]

Association Between Vitamin B12 Levels and Mortality in Hospitalized Older Adults (http://onlinelibrary.wiley.com/doi/10.1111/j.1532-5415.2010.02721.x/abstract) (Feb 2010)


PARTICIPANTS: One thousand five hundred seventy patients aged 65 and older hospitalized at the KMC and Hartzfeld Hospital in 2007.

MEASUREMENTS: Blood vitamin B12 levels and demographic, clinical, and laboratory data obtained from electronic medical records.

RESULTS: Vitamin B12 deficiency (≤200 pmol/L) was found in 15% of older hospitalized patients. Fifty percent of the patients had high vitamin B12 levels (≥350 pmol/L), 68.2% of whom were aged 80 and older. Metformin use was clearly associated with lower vitamin B12 levels. In patients aged 65 and older, an inverse correlation was found between vitamin B12 levels and albumin, metformin, and angiotensin-converting enzyme (ACE) inhibitor use. Age, number of medications, and mortality were linearly correlated with vitamin B12 levels.

CONCLUSION: Higher vitamin B12 levels were associated with greater mortality, but it is unclear whether vitamin B12 is a marker or a surrogate marker or even a substance that directly causes death. Further investigation is needed to clarify. (DOI: 10.1111/j.1532-5415.2010.02721.x)


ETA:
Some more details about the same study here (http://www.springerlink.com/content/644r870713p50737/):

• High cobalamin levels (>400 pmol/l) occur in 33.8% of the
study population.
• There is a significant association between elevated serum B12 and mortality in elderly inpatients
• High B12 levels are associated with a 4.5 increase in
mortality in non cancer patients within the following 90
days
• High B12 is, independently of age, gender and the presence
of cancer, an important biomarker that should be included
in severity-of-illness measures in all elderly inpatients.
(The Journal of Nutrition, Health & Aging©
Volume 12, Number 3, 2008)

[Korn]

The article Is a Vitamin B12 Overdose Safe? (http://www.usingvitaminswisely.com/vitamin-b12-overdose.html) discusses the fact that there's no 'official' upper limit set for B12 supplementation, and concludes wisely: "Another factor against taking a megadose of B12 is that no research has been able to establish a safe upper limit of B12 consumption." (A couple of other sources have come to the opposite conclusion - that it's safe to consume any amount of B12 for as long you want because there isn't defined a known, safe 'upper limit' yet.

The B12/cancer link is also mentioned...


The most alarming aspect of a vitamin B12 is that it has been linked with several types of cancers. Another factor against taking a megadose of B12 is that no research has been able to establish a safe upper limit of B12 consumption.

The link between high levels of B12 and cancer is easy to explain. Vitamin B12 stimulates cell division and it doesn’t distinguish between healthy and unhealthy cells. The excess vitamin B12 provides the extra energy needed by cancer cells.

.... and in this context, they mention a case of leukemia resulting from a vitamin B12 megadose (http://www.amjmed.com/article/0002-9343%2884%2990872-6/abstract) used in the treatment pernicious anemia. I haven't seen the full article, and find abstract the itself kind of inconclusive.

The case is discussed here:
Pernicious Anemia: Presentations Mimicking Acute Leukemia: Discussion (http://www.medscape.com/viewarticle/472611_3)

Drabick et al[2] reported a case in which vitamin B12 replacement therapy resulted in the resolution of neurologic findings and macrocytosis; however, the anemia and monocytosis persisted. Cytogenetics continued to reveal a clonality and the MDS eventually converted to AML. They also pointed out that reversible cytogenetic abnormalities have been observed with megaloblastic anemia, even including karyotypes typically associated with MDS or AML. Vogelsang et al[3] reported another case in which 57-year-old women developed acute leukemia with coexisting pernicious anemia. There was a decline in circulating blasts after vitamin B12 replacement; however, the blast cells persisted in the bone marrow.

Ahman el al[4] went a step further with this issue, suggesting that excessive replacement of vitamin B12 may in some cases even accelerate underlying hematologic malignancies. This is based on the observation that patients with vitamin B12 deficiencies have an increased incidence of hematologic malignancies. They demonstrated in vitro that adding vitamin B12 could stimulate blast colony formation.

More about the cause/effect relationships between B12 and leukemia here:
Significance of elevated cobalamin (vitamin B12) levels in blood (http://www.ncbi.nlm.nih.gov/pubmed/14636871)

Elevated levels of serum cobalamin may be a sign of a serious, even life-threatening, disease. Hematologic disorders like chronic myelogeneous leukemia, promyelocytic leukemia, polycythemia vera and also the hypereosinophilic syndrome can result in elevated levels of cobalamin. Not surprisingly, a rise of the cobalamin concentration in serum is one of the diagnostic criteria for the latter two diseases. The increase in circulating cobalamin levels is predominantly caused by enhanced production of haptocorrin. Several liver diseases like acute hepatitis, cirrhosis, hepatocellular carcinoma and metastatic liver disease can also be accompanied by an increase in circulating cobalamin. This phenomenon is predominantly caused by cobalamin release during hepatic cytolysis and/or decreased cobalamin clearance by the affected liver. Altogether it can be concluded that an observed elevation of cobalamin in blood merits the a full diagnostic work up to assess the presence of disease.


Serum Concentrations of Vitamin B12 in Patients Suffering from Leukemia
(http://bloodjournal.hematologylibrary.org/content/9/8/789.short)

1. Vitamin B12 serum concentrations have been investigated in various types Of leukemia.
2. The concentration in chronic myeloid leukemia is approximately 15 times normal. In chronic lymphatic leukemia it is normal. In acute leukemia it is variable.
3. In chronic myeloid leukemia, the serum vitamim B12 exists in the bound form and the binding capacity for added B12 is increased.
4. Electrophoretic studies indicate that serum vitamims B12 in chronic myeloid leukemia is bound in the alpha globulin fractions.
5. Some correlation was found between serum vitamin B12 concentrations and total white cell counts in chronic myeloid leukemia. The possible significance of this is discussed.

SERUM CONCENTRATIONS OF VITAMIN B12 IN ACUTE LEUKEMIA
(http://www.annals.org/content/41/2/323.extract)

In a previous paper,1 serum concentrations of vitamin B12 in patients suffering from chronic leukemia were reported. It was shown that, in chronic lymphocytic leukemia, serum contains a normal concentration of the vitamin, whereas in chronic myelocytic leukemia the concentration is markedly increased.

A preliminary report of serum vitamin B12 concentrations in seven cases of acute leukemia suggested that the variable concentrations found might be associated with morphologic differences in cell types such as occur in chronic leukemia. In this paper a morphologic diagnosis has been attempted in 20 cases of acute leukemia, and comparison made with the serum vitamin... (This 100-word excerpt has been provided in the absence of an abstract.)

[Korn]

According to studies quoted in the article REVISED REVIEW OF VITAMIN B12 (http://www.food.gov.uk/multimedia/pdfs/EVM0020P.pdf), found in food.gov.uk (http://www.food.gov.uk/multimedia/pdfs/EVM0020P.pdf):

Poirier (1975) reported that dietary supplementation with vitamin B12 (0.5 ppm ; ~ 25
µg/kg/day[3]) significantly lowered survival time of rats with hepatocellular carcinoma
induced by diethylnitrosamine. Kal’nev et al (1977 – Russian with abstract in English,
cited by Miller and Hayes 1982) found that treatment with methyl Cbl or cyanoCbl (route and dose uncertain) reduced the survival of rats with implanted hepatoma or carcinosarcoma.
(It always feels kind of awkward to quote animal studies on a forum for vegans - but it would IMO be wrong to not mention existing studies which may provide important info or cause further studies on humans....)

Both too low and too high amounts of B12 have been associated with increased cancer risk, and the same article also refers to a study which "showed that intraperitoneally administered methyl Cbl and deoxyadenosyCbl, but not cyanoCbl, increased survival time of mice implanted with P388 leukemia tumour cells. Shimizu et al (1987) demonstrated increased survival and reduced growth of innoculated ascites tumour cells in mice treated with methyl Cbl.".

One reason there are relatively few studies on B12 overdosing are that very few people knowing what they're talking about recommend really high amounts of B12 for other than treatment of B12 deficiency. Since are some reports confirming an association between high B12 levels and cancer, it would also be highly questionable to invite someone to take, say, 1000 mcg B12 daily for 2-r years and see if they ended up with a higher cancer rate or lower cancer survival rate than a control group with a normal B12 intake (usually around circa 3-8 mcg B12, including up to 5-30% inactive B12 analogues).

A few cases of allergic reactions against B12 supplementation are also discussed in the documented above.

[Consistency]

According to http://www.isn.net/~deighanj/v&m-pag2.htm (http://www.isn.net/%7Edeighanj/v&m-pag2.htm), 'there are reports that supplementation with vitamin B12 may induce an acne like eruption on the skin or worsening of acne if present.'

Vitamin B12 molecule doesn't cause Acne. What causes Acne is the rancid fatty acids in the supplement that poison and inhibit the growth of Acne bacteria. The bacteria fights back against the host which triggers an immune system reaction leading to a war between white blood cells and Acne bacteria.

Poor bacteria.

[inspiteofjane]

Hey all! (late reply) but quick question. I just discovered nutritional yeast which is very high in b12, and have been putting it in everything, for a week or two and today I woke up with hive looking rashes along my arms!! Can a b12 overdose and reaction happen this quickly?