Vitamin B12 Facts for Vegans

by Heather Nicholds, Registered Holistic Nutritionist

B12 is a nutrient that gets debated a lot in the world of vegan nutrition. Some say that you can get all the B12 you need from fermented foods, yeasts and algaes. Others say that these forms of Vitamin B12 are ones that our bodies can't use, and that supplements or fortified foods are the only ways to get B12 as a vegan.

The research referenced by the sources I trust the most (such as have said that, unfortunately, the second version is true. If you eat a vegan diet, you absolutely need a supplement to ensure you're getting enough B12.

The good news is that although animal foods are commonly cited as food sources of B12, the vitamin is made by bacterial fermentation. In fact, this is one case where supplements are actually a better source of a nutrient than food. Supplements made from bacterial sources of B12 are a more direct form of B12.

The National Academy of Sciences, which amalgamates research to set RDI amounts, recommends that anyone over the age of 50, whether they eat meat or not, takes a supplement of vitamin B12 because it's a nutrient that's difficult for our digestive systems to extract and utilize from our food, and as we age our digestive function gets less efficient.


Not only do we as vegans know that animal foods involve suffering, cruelty and slaughter, they also come along with hormones, antibiotics and inflammatory compounds (like arachidonic acid) that are not healthy for our bodies. So a healthful, whole foods vegan diet with a few important supplements, like B12, makes sense to me as the best overall package.

Since excess Vitamin B12 can be stored in the body for many years, and deficiency symptoms creep in over time, vegans aren't always aware of the fact that they've become deficient. I often wonder if some of the people who give up on veganism because they run into health problems simply needed a B12 supplement to correct their issues. That's why I think it's so important to recognize this nutrient and its importance to our health, so that we can ensure as many vegans as possible and healthy and vibrant examples of a compassionate lifestyle.

Early Symptoms of B12 deficiency:

  • Unusual fatigue
  • Faulty digestion
  • No appetite
  • Nausea
  • Loss of menstruation
  • Tingling hands and feet (start of serious deficiency)

If you let a B12 deficiency go on from there, it can result in permanent nerve damage and get very serious, causing blindness or deafness. Also, homocysteine levels will be high (risk factor for heart disease, stroke and complications during pregnancy) long before any of the early symptoms show up.

If children don't get enough B12 during childhood, their levels can be corrected but the period where they didn't have enough can have permanent effects on their brain and nerve functions.

You can be tested for B12 deficiency by your doctor, and the most accurate method of testing is a urine or blood test called a Methylmalonic Acid test (MMA). It can detect deficiency much earlier than the standard blood test most doctors use to test for serum cobalamin levels and pernicious anemia.

Since anemia doesn't show up until about 2 years after a deficiency starts, and the risk of damage to your brain and nervous system happens before anemia you want to make sure you don't let yourself get to that point. Also, standard blood test results may not be accurate if folic acid levels are higher than normal, or if there are B12 analogues (forms that your body can't use) in your system.

Vegan Sources of Vitamin B12

In Healing with Whole Foods, Paul Pitchford says that the long-term vegan cultures that are used as examples of veganism providing all necessary nutrition are actually getting their B12 partially from the small insects on their greens and produce. The other advantage they have is that manufacturing regulations are not so strict on sanitation, so the naturally fermented foods they eat have enough bacteria to produce B12.

Testing on commercially-produced fermented foods (i.e. tempeh, sourdough bread) in North America has shown very low levels of B12. Yeasts may or may not have B12, and algaes may only have an analogue of B12 that isn't able to be used. Greens powders list a large amount of B12 in their nutritional breakdown, but this is from algaes so may not be usable by our bodies.

There hasn't been proper testing done on these things to see whether or not they are both absorbed and used by humans. For a very thorough analysis of available research on plant sources claimed to provide B12, read

Although these sources could have some usable B12, since deficiency of vitamin B12 is so common among vegans who don't supplement (see and, and since it is a deficiency that can actually have pretty serious consequences I go with the 'better safe than sorry' strategy and make sure that I have a B12 supplement.

How Much Vitamin B12 Should You Take?

There are different types of B12 supplements: tablets, capsules, liquid. I tend to like liquid supplements since they don't need to be broken apart physically by your system, so they have the best chance to be fully absorbed. There are chewable tablets which are great, and capsules tend to be easily dissolved as well. Sublingual (under the tongue) supplements are often positioned as a better option, and they may well be but there's no conclusive evidence that it makes a significant difference in the absorption rate. Any of those forms will work, and the best one is the one that you'll find easiest to take on a regular basis.

There are also two different forms of the vitamin: methylcobalamin and cyanocobalamin. The supplements using methylcobalamin often promote that as the more active and effective form of the vitamin, but the truth is that both forms are just as effective. The argument against cyanocobalamin is that it leaves cyanide in your system as it metabolises. The truth on that is that the amount is so small that it doesn’t have any negative health effect and your body will clear it as it does any other toxin. You need a larger dose if you take methylcobalamin, and the supplements are often more expensive, so it winds up costing more to go that route.

The US RDI minimum for Vitamin B12 is 2.4 mcg per day for adults, and 2.8 mcg for pregnant or nursing women. More recent studies put the ideal intake at 4-7 mcg per day. (Click for more info on optimum levels: Since B vitamins stimulate energy and the nervous system, it's better to take them in the morning and early afternoon so that you don't get wired before going to sleep.

You can take B12 as one large weekly dose, or more often in smaller doses, whichever schedule works better for you. Our bodies only absorb and utilize part of what we ingest, so you need to get much more than the RDA as a supplement. Taking a supplement of 250mcg per day or 2500 mcg per week will both get you enough B12.

Vitamin B12 is a nutrient that you can't overdose on, because your body flushes any excess in your urine. If you notice bright yellow urine after taking a supplement that means you've taken more than enough. My opinion is that it's an inexpensive supplement that is incredibly important, so I'm happy to take more than enough to be safe.

Some fortified plant foods (non-dairy milks, meat replacements) are fortified with B12 (and other nutrients). Personally, I don't like to rely on these for B12 intake, because it is difficult to calculate day to day, and you can become over reliant on processed foods like meat substitutes. I also prefer choosing a high quality supplement rather than relying on the type of supplement the manufacturer has chosen to add to the food.

Vitamin Supplements vs Nutritional Yeast?

Although some foods like nutritional yeast contain B12, it's only there if the vitamin is specifically added in the manufacturing process. The amount of fortified nutritional yeast one would have to eat to get the daily intake of B12 is pretty large, and with no other health benefits I don't think it's a nutritionally sound food source to obtain the full intake of B12. The B12 found in nutritional yeast is in no way superior or better absorbed than the B12 found in supplements. I use nutritional yeast quite often as a flavoring, but not as a source of B12.

Many thanks to Jack Norris, RD (, for reading and providing additional insight on the information shared above.

Further reading:

About the author: Heather Nicholds is a registered holistic nutritionist who helps clients energize their lives through simple changes in how they eat. Whether you’re seeking healthy weight loss, more energy or a boost towards balanced nutrition, Heather will introduce you to the positive and powerful impact of a plant-based whole food diet. She shares her knowledge, enthusiasm and experience to help you prepare quick, healthy, delicious and balanced meals that leave you and your family full of vitality!

Visit her site here:

Related topics you might like:

Disclaimer: The views expressed in articles published on HappyCow are those of the authors alone. They do not represent the views or opinions of HappyCow nor its staff.

Some links in this article are possibly part of Amazon's affiliate program, so when you make a purchase a small amount will go to support the HappyCow website.

This information is not intended to replace the diagnosis, treatment and services of a physician. Any recommendations and indications are at the user's discretion. For severe or life-threatening conditions, always seek immediate medical attention. While we work to ensure that product information is correct, and list only products containing vegetarian ingredients, on occasion manufacturers may alter their ingredient lists. Actual product packaging and materials may contain more and/or different information than that shown on our Web site. We recommend that you do not solely rely on the information presented and that you always read labels, warnings, and directions before using or consuming a product. For additional information about a product, please contact the manufacturer. HappyCow assumes no liability for inaccuracies or misstatements about products.