Vitamin B12 Information: What You Need To Know

Basic Vitamin B12 Information

Functions of Vitamin B12

- Required to make red blood cells

- Required to create the myelin sheath surrounding nerves

- Required for the synthesis of DNA and fatty acids

- Required for the metabolism of methionine and homocysteine, along with vitamin B6 (pyridoxine)

- B12 can be stored for long periods of time in the liver (between 2-5 mg), so deficiencies are rare or don’t arise for years

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Folic acid and cobalamin are often referred to as the "B12 vitamins" because they work hand in hand in a few essential reactions, namely in the metabolism of methionine and the breakdown of odd-chain fats. My personal opinion says they should be separated into different vitamins. Each one will be discussed at some length on this page.

Vitamin B12 information has been so skewed in recent years due to media and marketing's a vitamin that's been in the spotlight for quite a while now. Let's throw all the myths aside and learn about the true facts behind the vitamin.

For starters, vitamin B12 is required for 2 essential reactions in the body: one involving the creation of methionine (an essential amino acid) from homocysteine and the other in the breakdown of odd-numbered fatty acid chains (a fat with an odd number of carbon atoms).

Many people advocate that the benefits of vitamin B12 include increased energy - but I don’'t really see it. These same people indicate that the more B12 you can get, then the more energy you'll have. No!

This is a marketing ploy because taking too much of the vitamin has no real side effect (keeps them out of lawsuits!). So they try to sell as much of it as possible, even if it doesn't really help you. Make sure you have the right vitamin B12 information so you don't make any misinformed decisions! This page is a good place to start!

The bottom line is if you have enough B12, your body functions normally. Too much vitamin B12 is simply excreted in the urine (granted the urine will be neon green, but that's a story for later). My advice would be to take excessive B12 supplements if you want expensive urine. You really don't need much of this stuff to live off of!

Reference Nutrient Intake (RNI)

a.k.a. Recommended Daily Allowance

As with any vitamin, the recommended intake depends on age, gender, body type and metabolic activity. Here's a table to help put things in prospective. If you're overall a healthy individual, don't let anyone tell you that you need more B12! Obtaining the right vitamin B12 information is essential. So here it is. And believe me, you don't need much of it!

Recall that 1 mcg (microgram) is the same as 0.000001g...

Recommended Daily Intake of Vitamin B12 (mcg: 1000 mcg=1 mg)
Adult Males1.8-2.0
Adult Females1.8-2.0

**Keep in mind here that lactating women require more B12 than normal individuals so as to ensure enough of the vitamin in breast milk.**

Sources of vitamin B12 information have recently become unreliable. There're tons of myths out there about whether you should take cobalamin (B12) supplements along with food sources of vitamin B12. Here's a no B-S table about where you can get plenty of the vitamin...

Good Food Sources of Vitamin B12
PoultryLow Fat DairyWhole Milk
OystersFresh ShrimpPork

Side Effects of Vitamin B12 Overdose

B12 toxicity is very low and only in very rare instances are B12 side effects apparent, most of which occur in extremely rare genetic disorders.

However, the light-reflecting properties of B12 has been exploited in some not-so-excellent ways. It has unfortunately become common practice to use excessive B12 supplementation as a way to try and cover up urine samples that may otherwise result in a positive drug test. The idea is to drink tons of water (to dilute the drug) - but because this causes the urine to be clear, B12 is supplemented to give the urine a neon greenish tint, a pseudo-urine appearance.

Now that medical professionals are more aware of this situation, the sample very rarely passes and a second sample is usually required. This is because the urine appearance has a distinct, odd color that usually results in some red flags.

On that note, if you take a multivitamin, your urine may turn a neon green color - this is in fact due to the excreted B12 and there's nothing wrong with your kidneys.

Vitamin B12 Deficiency

So you think you have low vitamin B12?

A vitamin B12 deficiency is rare in normal individuals because the vitamin is stored over long periods in the liver and is taken in readily from any animal product. If you eat any sort of protein-rich animal food, you'll be getting enough vitamin B12 and B12 supplements won't be necessary. In fact, people don't seek vitamin B12 information on deficiencies and symptoms until years after the actual onset of B12 deficiency. How can this be?

Well, B12 is secreted in the bile, a substance released from the liver that aids in the digestion and absorption of fats in the intestine. B12 then re-enters the circulation in a pathway known as the enterohepatic circulation. Furthermore, many of the microorganisms that live happily in the intestines synthesize vitamin B12 regularly. In short, the B12 is absorbed and reabsorbed automatically, without having to take in much B12. The supply does run out eventually, however, if none is taken in the diet (e.g. a "tea and toast" diet).

It’s generally believed that B12 is subsequently absorbed and, just like B12 from the bile, re-enters the circulation. This description has received criticism, however, since many of these bacteria reside too far down in the intestine for significant absorption to occur. Vitamin B12 can also be found in the feces which is strong evidence for this criticism.

When someone does have low vitamin B12, however, it's normally due to a problem with absorption of the vitamin rather than dietary deficiency. For example, individuals greater than 50 or 60 are at risk of being deficient in the vitamin because their bowel simply absorb nutrients as efficiently as it used to. There's also an autoimmune condition known as "pernicious anemia" in which the stomach secretes very little intrinsic factor (a protein that binds B12, beginning the absorption process). Pernicious anemia is often associated with thyroid disorders, lupus, scleroderma, rheumatoid arthritis and other autoimmune conditions. If you're over 50, you should have your B12 levels checked by a doctor to ensure you're getting enough of the vitamin in your diet (high blood levels of methylmalonic acid is an indication of a vitamin B12 deficiency). This test is usually done in conjuction with blood calcium levels, vitamin D levels and often a bone density test (DEXA scan) in older women.

The exception here is for strict vegetarians who eat no meat products - B12 is found only in animal products. With this said, here's a small word of caution for the vegetarians...

False B12

Nutrition labeling laws are somewhat quirky and often misleading, especially when it comes to vitamin B12 information. Marketers have claimed that spirulina, tempeh and nori are excellent plant sources of vitamin B12 - this claim, however, is false (based on the labeling).

The problem here is that obtaining accurate vitamin B12 information or content is normally done when certain microorganisms grow on the product in question. In other words, these organisms flourish on tempeh and spirulina while not on other plants due to the content of "vitamin B12". This growing is in fact only allowed due to the presence of a B12 analogue, often known as "false B12".

False B12 is not a source of vitamin B12 for humans as it turns out. In fact, it could be involved in actually blocking cellular B12 receptors and subsequently the important reactions that require B12.

As a further word of warning, antioxidants such as vitamin C and vitamin E, iron, copper, glutathione and even thiamine (vitamin B1) are antioxidants, meaning they involve the removal of free radicals (extremely reactive molecules that can damage cell tissues) from the immediate environment. However, when all of these ingredients are put together in a single multivitamin tablet, these antioxidants sometimes (not always) react with each and negate the effect of natural vitamin B12 and convert it into false B12.

Therefore it's extremely important to get your B12 from natural sources (no plants!) if possible. It's easy to see why vegetarians can easily be deficient in the vitamin and more often seek vitamin B12 information.

Symptoms of Vitamin B12 Deficiency

Symptoms of vitamin B12 deficiency include anemia, weakness, fatigue, constipation, excessive flatulence, weight loss (due to a loss of appetite) and tongue soreness. Remember, these are normally due to absorptive problems as opposed to dietary deficiencies. It's important to seek appropriate vitamin B12 information and medical advice if you think you may have a B12 deficiency.

Because B12 is used to make red blood cells, it's obvious that a vitamin B12 deficiency will lead to anemia (a loss of functional red cell volume) which can sometimes be severe. B12 is also needed to create the myelin sheaths surrounding nerves which allows them to function properly. What's this you ask?

A myelin sheath is a coat of fat surrounding nerves for electrical insulation, similar to the rubber surrounding a wire. It prevents electrical impulses from leaking out of the nerves - therefore a loss of sheath function can cause uncoordinated movements. In severe cases, loss of fine touch sensation may occur in the extremities (dorsal column atrophy).

Folate and Homocysteine

A vitamin B12 deficiency will also cause an increase in blood levels of homocysteine (from the metabolism of methionine) which is highly correlated with heart disease and stroke. This is because high levels of homocysteine promotes blood clotting which can clog arteries in the heart or brain.

This reaction also involves the formation of folate (the formation of methionine from homocysteine - a reversible reaction). So, if this reaction doesn't go, you're going build up homocysteine also cause a folate deficiency (a.k.a. folic acid).

But wait, many people take folate supplements! The fact is that folate supplements provide a source for the nutrient when the reaction above is nonfunctional, negating the effects of a folate deficiency resulting from the B12 deficiency (a situation also known as the folate trap). So what does folate actually do?

In short, without folate, the effects of vitamin B12 would never occur. Why? Basically, folate is the precursor to a cofactor known as tetrahydrofolate (along with some other derivatives such as methylene tetrahydrofolate) which is required for any reaction involving the transfer of a single carbon atom.

As it turns out, tetrahydrofolate interacts with vitamin B12 in the synthesis of DNA (namely methionine, which is needed to start a new DNA strand) and creating new red blood cells. Without the cofactor, the individual will become anemic because the creation of new red cells is too slow or inefficient.

This isn't the whole story behind Folate! In fact, folate deficiencies in a pregnant mother may cause neural tube defects in the newborn. Check out my page on folic acid for more information.

Pernicious Anemia

As I mentioned above, a deficiency in vitamin B12 is rarely due to a dietary deficiency, but rather a failure to absorb the vitamin in the intestine. It's usually caused by an autoimmune disorder that destroys parietal cells that line the stomach - those very cells that secrete intrinsic factor (a glycoprotein secreted by parietal cells that binds B12 and is required for B12 absorption and metabolism). In other words, if you don't secrete intrinsic factor, you don't absorb B12 and you eventually become deficient in B12 and folic acid.

Individuals with this disorder are usually anemic (have a low red cell volume) and may develop neurological problems as time progresses (because the fatty myelin sheath surrounding their nerves are being degenerated in the absence of B12). The neurological symptoms are irreversible and can occur in the absence of anemia. Treatments include direct injection of a compound known as cyanocobalamin which must be continued indefinitely.

Vitamin B12 Supplements

Now that we have all the vitamin B12 information we need, let's think about who might actually need a vitamin B12 supplement program...


Because B12 is only found in animal foods, strict vegetarians often need vitamin B12 supplements because they aren't getting any of the vitamin from their diet. Fortified cereals may be a decent source for the vitamin (even though it comes from plants) but I'd have my doubts. In general, if it's something you can dig out of the ground, it probably doesn't have B12. Choose your source carefully. Even some supplements contain that "false B12" that I alluded to earlier.

Pernicious Anemia

Individuals with pernicious anemia need B12 supplements for the continuance of life. Basically, the parietal cells of their stomach (the ones that secrete intrinsic factor, a glycoprotein required for B12 absorption to occur) have been destroyed.

Gastronintestinal Disorders

Many people have had their stomachs stapled to aid in weight loss, gastric bypass surgeries or colon cancer. Basically, any disorder that disrupts the lining of the intestine or the stomach can result in a vitamin B12 and/or a folate deficiency. Even microorganisms like Helicobacter pylori destroy the mucus layer of the stomach, resulting in the acid digestion of parietal cells.

Was That Enough Vitamin B12 Information?

The goal of this page was to give you the right vitamin B12 information in a way that's digestible for the general audience. Too many people out there are falling for misinformation so that marketers can dig into their wallets - stay away! No matter what you seek, make sure you're getting the right information from the right places. Many people receive vitamin B12 information that's either outdated, faulty or extremely misleading.

There's actually quite a bit more vitamin B12 information to write about, but it's really not necessary for general knowledge about the vitamin, especially with respect to nutrition and strength training. Hope it was helpful!

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