Picture a no-holds-barred diet debate. The topic: “Is a vegan diet healthy for humans?” The anti-vegan debater utters two syllables and drops the mic, confident of victory. What are those syllables? “B” and “12.”
Here’s the deal: B12 is an essential vitamin for many bodily functions. And many people can’t get enough B12 from an exclusively plant-based diet without some supplementation. Therefore, the anti-vegan concludes that plant-based diets are unnatural and unhealthy. Case closed, and let’s break out the ribeyes.
Well, not so fast. While it’s true that B12 is an essential nutrient, and it’s almost impossible to get it from plants, there’s a lot more to the story. Many non-vegans and non-vegetarians are also low on B12 for a variety of reasons, mainly inadequate absorption.
No matter what your diet, this article tells you what you need to know about B12. You’ll find out what it is, where it comes from, why it’s so important for your health, how much you need, and where to find the healthiest sources.
What Is Vitamin B12?
Of all the known vitamins, vitamin B12 is the largest and has the most complex structure. (Think of it as the vitamin equivalent of book five of the Harry Potter series.) Like all the other B vitamins, B12 is a water-soluble vitamin. But while your body only uses what it needs and excretes the rest with most water-soluble vitamins, B12 is the only B vitamin that’s primarily stored in the liver (with trace amounts in other organs as well).
Your body can store vitamin B12 for a long time (two to five years, on average), although it’s still important to get a regular supply in order to prevent deficiency. Its storage is likely due to the multiple critical functions it has in the body.
Your body requires B12 to form red blood cells, to keep your brain functioning well, and to synthesize DNA. B12 also plays an essential role in amino acid, fatty acid, and folate (vitamin B9) metabolism, the latter of which is a critical nutrient for reproduction. In other words, without B12, there’s no life.
One of the key ways B12 participates in these functions is through the mineral cobalt. (It turns out that Wolverine isn’t the only one with a partly metallic body!) B12 compounds are also known as cobalamins because of the cobalt that sits in the middle of the vitamin B12 molecule.
While ruminant animals like cows and sheep can synthesize B12 from cobalt and absorb it from their small intestines, humans cannot. Instead, we need one of the active forms of B12 — either methylcobalamin or adenosylcobalamin.
B12 Benefits for Your Health
Vitamin B12 is critically important for a lot of reasons. It contributes to a vast array of processes that keep your body running smoothly and support your overall health. Here are just a few crucial benefits of B12.
1. Vitamin B12 and Depression
Getting enough vitamin B12 supports brain health and a positive mood. Observational studies have found that approximately one-third of patients who are admitted for clinical treatment of depression are deficient in vitamin B12. Supplementing with B12 may also prevent depression or increase the efficiency of prescribed antidepressant drugs.
2. B12 and Heart Disease
Vitamin B12 helps regulate levels of the amino acid homocysteine, a byproduct of protein metabolism. High levels of homocysteine have been linked to a higher risk of heart disease, stroke, and dementia. Homocysteine levels increase when B12 levels are deficient and decrease when there is enough B12 in the body. (Think of B12 and homocysteine on opposite sides of a see-saw.) Many studies conducted since 1999 found that vegans who were not supplementing with vitamin B12 had unusually high levels of homocysteine. In contrast, those who did supplement had homocysteine levels within a normal range.
3. Vitamin B12 and Eyes
Vitamin B12’s ability to bring down homocysteine levels benefits not only your cardiovascular system and your brain but your eyes as well. Elevated homocysteine levels appear to increase the risk of several eye-related diseases, including (warning: list of medical jargon coming up) retinopathy, cataracts, optic atrophy, retinal vessel atherosclerosis, and pseudoexfoliative glaucoma maculopathy (I don’t recommend trying to say this five times fast).
And that’s not all. Age-related macular degeneration is associated with both high homocysteine levels and low levels of vitamin B12. The good news is that vitamin B12 and folate supplementation can help older people reduce the high homocysteine levels that can lead to eye disease. Remarkably, the topical application of vitamin B12 along with citicoline — a naturally occurring brain chemical sometimes used in supplements — to the eyes of patients suffering from diabetic retinopathy regrew damaged nerves, improving their corneal nerve health. Now that’s some real-life magic right there!
4. B12 Protects Against Neural Tube Defects in Pregnancy
Neural tube defects are serious birth defects that can change the function or shape of the spinal cord and brain. While we most often hear about the importance of folate for preventing neural tube defects, vitamin B12 also plays a crucial role. Fetuses of mothers with low levels of vitamin B12 are at a higher risk for neural tube defects, including spina bifida and anencephaly, among others.
5. Vitamin B12 and Red Blood Cell Production
Vitamin B12 also helps to make sure you have enough red blood cells in circulation. In turn, it supports oxygen availability in your body and may improve athletic performance.
A 2020 study published in the journal Nutrients examined 1,131 blood samples collected from 243 track and field athletes over six years and compared the results to athletic performance. The researchers concluded that the ideal athletic performance was achieved when blood levels of B12 were in the range of 400–700 pg/mL (that’s picograms per milliliter. And in case you’ve never heard of a picogram before, it’s one trillionth of a gram).
6. B12 and DNA
Vitamin B12 has antioxidant properties, which is one of the reasons it can both protect your cells from damage caused by free radicals and reduce your cancer risk. If Jeff Goldblum had gotten enough B12, I suspect The Fly would have been a very different (and much less scary) movie.
Having enough vitamin B12 in your system can also help protect you against the toxicity of some drugs. One 2014 study, for example, found that vitamin B12 was protective against the known free radical damage caused by Paclitaxel, an anticancer drug that leads to irreversible cell injury.
A 2018 study also found that vitamin B12 reduced toxicity from hydrochlorothiazide, a diuretic drug used to treat high blood pressure and fluid-related swelling.
Where Does Vitamin B12 Come From?
There are many misconceptions about B12, but the truth is that this critical vitamin does not come from meat. Rather, B12 is made only by bacteria and single-celled organisms. And where, pray tell, are these B12-producing microorganisms found? They are in the soil and the small intestines of animals, including humans.
Nowadays, though, much of our farmland is relatively lifeless. Instead of being rich in compost and microorganisms, it’s inundated with synthetic fertilizers that deliver heavy metals, which compete for bioavailability with essential minerals like B12.
Meanwhile, our society has developed a collective fear of dirt and germs. While antimicrobial efforts have undeniable public health benefits, they also have serious negative side effects, including a lack of bioavailable B12 in our environment.
And remember our anti-vegan debater crowing about the fact that vegans have to supplement with B12, and how it “proves” that their diet is inherently unhealthy and unnatural? The sad truth is that even factory-farmed animals can sometimes be B12 deficient. Young sheep and cattle may get B12 from milk, formula, or injections. Even mature animals may get B12 injections or supplements in areas with sandy soils low in cobalt (cobalt is needed to synthesize B12). This means that no matter where you’re getting your B12, it’s likely to depend at least in part on supplementation. The real question is whether you supplement directly or take it through a middleman, er, middle-cow, or middle-sheep.
How Much Vitamin B12 Do You Need?
It’s not just a matter of how much B12 you take in; it’s also how much you can use. The vitamin must be bioavailable. And you must be able to absorb and transport it efficiently as well. For instance, optimal B12 absorption can only be achieved when the digestive system has enough intrinsic factor — a protein that binds B12.
And with all of the factors in our world today that can throw off our gut microbiome, it’s not just vegans or vegetarians who are at risk for B12 deficiency. In fact, according to one study of over 2,500 people conducted a while back by researchers at Tufts University, up to 39% of the US population could have low B12 levels. That’s why it’s crucial to understand how to get vitamin B12 from dietary and/or supplemental sources, and how much you need in order to maintain optimal levels.
Below are the recommended daily needs for vitamin B12, based on established Adequate Intake and Recommended Dietary Allowances:
- 0–6 months: 0.4 mcg (micrograms, or millionths of a gram)
- 7–12 months: 0.5 mcg
- 1–3 years: 0.9 mg
- 4–8 years: 1.2 mcg
- 9–13 years: 1.8 mcg
- 14+ years: 2.4 mcg
- Pregnancy: 2.6 mcg
- Lactation: 2.8 mcg
As you can see, the recommended intake varies depending on age, pregnancy status, and diet. However, data on minimum daily needs can be misleading. The truth is that if your absorption is suboptimal for any reason, which is increasingly the case as you grow older, your actual needs might be higher.
B12 Deficiency
If you don’t get enough vitamin B12, either because of inadequate intake or poor absorption, you’re at risk of a B12 deficiency.
What are some of the more common symptoms of B12 deficiency? They can include fatigue, weakness, constipation, loss of appetite, weight loss, tingling of hands and feet, sore mouth or tongue, difficulty balancing, confusion, and poor memory. In infants, it can look like failure to thrive, movement disorders, and developmental delays.
Of course, the best way to assess your vitamin B12 status is to have your blood levels tested. A vitamin B12 test can be done at the same time as other general labs at a wellness check-up. But because it’s not a standard test, you will have to request it in most cases. You can also order it yourself in most US states through Quest Health.
In Western medicine today, B12 deficiency is generally suspected when blood levels of B12 fall below 200 pg/mL. However, research suggests that levels of at least 400 pg/mL are closer to optimal.
There’s another issue to consider: It’s possible to have sufficient levels of B12, as measured by blood tests, but for some reason, your body isn’t using it. One of the important functions of B12 is to convert a substance called methylmalonic acid (MMA) into other chemicals that aid in metabolism. If your MMA is high, you may be short of B12, or your body may not be using its B12 stores properly.
You can get your MMA checked via a blood or urine test.
Similarly, high levels of homocysteine can indicate a problem with B12 — either insufficiency or poor usage. A homocysteine test, like an MMA test, can help diagnose the root causes of B12 issues.
Who Is Most At Risk for Vitamin B12 Deficiency?
While vitamin B12 deficiency is common in many regions worldwide, certain groups are at higher risk in developed countries.
The most common cause of B12 deficiency is poor absorption, which can result from conditions such as irritable bowel disease, celiac disease, AIDS, or bacterial overgrowth in the small intestine. Older adults are also at heightened risk of B12 deficiency because absorption worsens with age.
People with MTHFR genetic mutations may also be more prone to B12 deficiency. This is because this particular mutation inhibits how your body can process B vitamins, including folate and B12.
Additionally, vegans and other plant-based eaters who follow a diet that excludes animal products are at a higher risk of B12 deficiency. This is because animal products are the most abundant dietary sources of B12.
Vitamin B12 Sources & Absorption
While a whole foods, plant-based diet can provide optimal levels of almost all of the nutrients you need, vitamin B12 is one of the only ones that isn’t easily sourced from plants.
The main dietary sources of vitamin B12 include:
- Most animal products (for those who eat them), including fish, beef, poultry, dairy products, and eggs
- Fortified foods like certain plant-based milks and yogurts, cereals, nutritional yeast, and tofu
Trace amounts of B12 can also be found in some mushrooms, fermented foods like tempeh, stinky tofu, and kimchi, and tea drinks like kombucha. However, these are not reliable enough sources to increase B12 to sufficient levels.
B12 is too important to leave to chance. If you follow a plant-based diet, it’s important to include a B12 supplement to meet your needs.
Vitamin B12 Supplements
Taking a B12 dietary supplement is necessary for plant-based eaters. But considering how many omnivores are deficient in B12, it might also be advisable for other people. B12 supplements are easy to find and are one of the least expensive supplements on the market.
There are several different forms of B12 supplements available. So which one is best? Believe it or not, some natural health advocates get remarkably heated on this topic.
Cyanocobalamin vs Methylcobalamin
The most widely used B12 form is cyanocobalamin, mainly because it’s cheaper and more stable to manufacture than other forms. When you ingest cyanocobalamin, your body converts it into one of the two active forms of vitamin B12: methylcobalamin or adenosylcobalamin. And some studies indicate that cyanocobalamin may be better absorbed, so score one for team cyanocobalamin.
The next most popular form is methylcobalamin, which is the natural form (the kind found in food sources), whereas cyanocobalamin is synthetic. Some studies have found that, compared to methylcobalamin, more cyanocobalamin is excreted through urine, suggesting that, in fact, methylcobalamin may be retained better.
Some people also rail against cyanocobalamin by explaining that it is made with cyanide (a poisonous substance). Cyanocobalamin does indeed include a cyanide molecule. But the good news is that even at a high dose, you’ll still be getting a thousand times less cyanide than is toxic. And the tiny amount of cyanide is excreted in the urine. So, while this sounds terrible, it probably isn’t cause for alarm. Even if you don’t have the constitution of Rasputin, this form of B12 is not poisonous.
That said, if the cyanide factor makes you want to opt for methylcobalamin, I won’t blame you. Overall, available research around vitamin B12 suggests that the differences in bioavailability between these two forms may not be enough to recommend one over the other for most people. Instead, factors that affect the absorption of vitamin B12, like age and genetics, may be more influential than the form of the supplement itself.
Algae-Sourced Vegan B12
Another type of B12 supplement you might see is “vegan B12,” made from algae. These supplements are usually made with spirulina, chlorella, nori, or a type of blue-green algae known as Aphanizomenon Flos-aquae.
The problem with these algal-based B12 supplements is that they may contain what is considered pseudo-vitamin B12 which is a nonactive form. Aside from the fact that this B12 is not bioavailable to humans, it may interfere with the absorption of B12.
Some varieties of chlorella may contain some active B12 to varying degrees, but spirulina products predominantly contain pseudo-B12. More studies are needed to determine if algal-based B12 products are reliable sources of active B12. But in the meantime, it’s best to steer clear of these supplements and instead choose those with either cyanocobalamin or methylcobalamin.
Supplement Amounts
How much vitamin B12 should you take as a supplement? Generally speaking, it’s best to get your levels tested first to determine your baseline and adjust dosages accordingly.
The registered dietitians at VeganHealth.org, who have extensively researched vitamin B12 on a vegan diet, put together a helpful table with recommended regimens for supplementing vitamin B12. You can see that table here.
Vitamin B12 injections are another supplementation option. Physician-given injections are most often used for high-risk people with absorption issues or the MTHFR gene who are already vitamin B12 deficient. This method has the advantage of quickly correcting low B12 levels. Injections generally contain high levels of cyanocobalamin.
If you’re concerned you may have been remiss with your past B12 intake or simply want the most bioavailable option, Purality Health’s Micelle Liposomal B12 might be the best choice. This high-potency formula delivers 2,500 mcg of methylcobalamin per serving and is designed for maximum absorption. While it’s a more intensive and costly approach, it could be ideal for anyone who wants to address potential B12 deficiencies quickly. Click here to explore this option and take advantage of an exclusive discount for FRN members.
If you purchase either product through those links, each company will contribute a portion of the proceeds to support FRN’s mission (thank you!).
Vitamin B12 Risks and Interactions
In general, high doses of B12 are considered safe with a low risk of toxicity, and there is no established upper tolerable limit for this nutrient. If you’re taking an oral supplement, there’s no known risk with taking a reasonable amount daily, even if you haven’t had your blood levels checked.
However, there may be some risks to B12 injections, which is why they should not, in most cases, be undertaken without support from a qualified healthcare professional. If you’re allergic to cyanocobalamin or cobalt, have low potassium levels (hypokalemia), kidney disease, a rare blood disorder called polycythemia vera, the eye disease Leber’s disease, or nutrient deficiencies like iron or folic acid, B12 injections are also not recommended due to higher risk for interactions.
Vitamin B12: Essential and Non-Negotiable
Vitamin B12 is an essential vitamin that’s necessary for good health. Plant-based eaters and older people are at increased risk of deficiency. Fortunately, even if you opt to forego all animal products, you can get all the B12 you need, and all the benefits from this versatile and critical nutrient, with a simple and affordable supplement.
Tell us in the comments:
- Do you take a vitamin B12 supplement? Do you need to make adjustments to your regimen based on the recommendations in this article?
- Have you ever had your blood levels of B12 checked? If so, what did you learn?
Feature image: iStock.com/Tero Vesalainen
