What Is Vitamin B12, And Where Does It Come From??

vegan b12 guide

Vitamin b12 is one of a group of water-soluble compounds that make up the vitamin B family. There are many critical bodily functions that the b vitamins play an active part in, from the maintenance of energy levels and healthy cell growth to preventing sigh degradation and improving neurological functions.

The Vitamin B family consists of the following compounds

  • Vitamin B1 (Thiamin)
  • Vitamin B2 (Riboflavin)
  • Vitamin B3 (Niacin)
  • Vitamin B5 (Pantothenic acid)
  • Vitamin B6 (pyridoxine)
  • Vitamin B7 (Biotin)
  • Vitamin B9 (Folate or Folic acid)
  • Vitamin B12 (Cobalamin)

Vitamin B12 is last on in the family of B vitamins but is no doubt one of the most important in any plant based vegan diet.

Vitamin b12 is the most complex in terms of its chemical structure out of all vitamins out there. It plays a crucial role in the production of red blood cells, our DNA development, brain function, nervous system, and overall energy levels. You can imagine if anyone becomes deficient in this vitamin, how much of a negative effect it can have on your overall health. Meat eaters and vegans alike should both be aware of the impact a lack of b12 can have on their system, and the first thing we need to all understand is that

b12 is not directly produced by the plants or by the animals, but by bacteria

Yes, it’s actually microorganisms that are the producers of this vital vitamin that plays such an essential role in all of our diets. These microorganisms/bacteria can be found in the stomachs of humans and animals and is also heavily seen in the soil and feces covering this planet we live on.

Different types of b12

There are four main types of vitamin b12 we should be aware of

  • Cyanocobalamin: Hardest for the body to use effectively, requiring 4 steps for the body to metabolize, making it the most inefficient form of b12. Many supplements still use this form of b12, but we recommend avoiding any supplement that uses this as the main base of their b12 formula.
  • Methylcobalamin: easiest for our bodies to use effectively
  • Hydroxocobalamin: converted to methylcobalamin in the body
  • Adenosylcobalamin: least used but rising in popularity. Very easy for the body to utilize like methylcobalamin. Supplements with a blend of this and methylcobalamin are pretty effective and do a better job then cyanocobalamin. 

Wait…so, why do we need external sources of b12 if we can produce it ourselves?

I can hear you shouting, “if we have the bacteria in our stomachs that allow us to produce vitamin b12, then why do we need to supplement with an external source? 

The answer is simple. The amount we can naturally produce without consumption through fortified foods or supplementation is not enough to avoid deficiency in the long run. It would be a long process to reach deficiency, however, without these external sources of b12, our personally created stash of vitamin b12 will slowly deplete. 

Key Benefits of vitamin b12 for vegans

benefits of vitamin b12

B12 plays a crucial part in many vital systemic functions of the body, but it is also important to remember that it works synergistically with vitamin b6 and folic acid for a lot of these processes. Think of b12 as one important piece of the puzzle that leaves the bigger picture incomplete without it, so balance is always key.

Best plant-based sources of b12

b12 foods

Plant-based sources that provide high enough levels of vitamin b12 for a vegan to confidently hit the recommended amount of vitamin b12 daily are few and far between. The main source that can be added to a vegan diet is algae and its many forms.


Algae is becoming well known for the multiple nutritional benefits it provides high levels of antioxidants and anti-inflammatory properties to its high levels of beneficial nutrients like protein, vitamin b, Omega 3, and it’s potential to lower cholesterol.

Key algae forms to be aware of


  • The average content of vitamin b12 is around 80-100 mcg per 100g
  • Has the highest amount of b12 from a plant source (found so far)
  • Good to add to a diet that is already consuming fortified foods or supplementing, especially because it has a wide range of other nutritional benefits such as protein, iron, omega 3’s, vitamin c and antioxidants
  • Still not a sufficient enough supply of vitamin b12 to use as the sole source of your daily vitamin b12


  • Contains vitamin b12 but the majority are inactive analogs meaning we cant utilize them efficiently
  • This overall makes spirulina a bad source of b12 as a whole but still a brilliant nutrient source to add to your diet for its many other nutrient benefits such as protein, b1, b2, b3, copper, iron, vitamin E and vitamin K


Fortified foods

Apart from algae, the evidence for other plant-based sources outside of fortified foods, being sufficient enough to deal with our vitamin b12 needs, is minimal. 

When understanding that b12 is created by bacteria, we have to consider how other animals gain enough without forming a deficiency. B12 being in the soil is one of the key ways other herbivores obtain sufficient b12 levels alongside the b12 being developed in their stomachs. We, as an overtly clean species in this modern day and age, get rid of the majority of the b12 creating bacteria that would usually be left on our vegetables through cleaning, chemical use, different forms of preservation, etc. 

Basically, we don’t eat as much soil and feces and as the other herbivores to cover our b12 needs, and in reality, why would we want to ……. right? 

Homegrown organic vegetables?

You may now be asking, “what if we eat our own homegrown, organic vegetables straight from the soil with no chemicals”? Yes, in this case, you may have a higher intake of vitamin b12, but this is not easy to manage regularly by the majority of people, and the amounts would be hard to measure. In the end, even if succeeding at doing this, there still may not be a significant amount of b12 to provide our bodies with what we need to prevent eventual deficiency down the line.

You would have to ask yourself, How would you measure your b12 amounts without a monthly blood test, and do you feel the potential risks that could come by choosing to avoid supplementation are worth it?  

How much vitamin b12 does a vegan need to avoid deficiencies?

  • The recommended daily amount of b12 ranges:  
  • It is important to remember that the RDA is in place to cover the minimal amount needed to avoid deficiency but doesn’t necessarily equate to the amount that will have your body running at its healthiest. 

Factors that can affect how much b12 is needed

Vegan/Vegetarian diet

Without the typical source of b12 that those consuming the western diet turn to (Meat, eggs, dairy) the dosage of b12 needed for vegans may be slightly higher than the RDA of 2.4mcg for adults.

Some studies show that consuming at least 6mcg a day may be optimal especially for vegans that partake in fitness.

A higher dosage than 2.4 mcg is also recommended here to equate for the low rate of absorption

Because current research has shown that b12 above 20mcg still shows no adverse effects, it may be safe to conclude that for a healthy non-pregnant individual having slightly more than the RDA (2.4-6mcg) may be a good way to ensure b12 levels are at an optimal amount and not just covering the minimal to avoid deficiency


As we age, we need more since our bodies become less efficient at utilizing b12, so we need to increase the dosage to make sure we are maintaining optimal levels as we get older so consuming above 2.4mcg per day through supplements and fortified foods can help to cover all bases.


Homocysteine is an amino acid in the bloodstream that people usually get from eating meat. For most vegans, this shouldn’t be much of an issue, but it’s important to understand its effects concerning b12

High levels of homocysteine have been linked to diseases such as dementia, osteoporosis, stroke, and heart disease

Studies have also shown a link between high homocysteine levels and eyesight loss over time

Sufficient vitamin b supplementation has been shown to lower homocysteine levels overtime seen here.

For vegans avoiding meat as a b12 source may mean slightly more supplementation than they may be used to, but taking one supplement a day is a minor drawdown in comparison to the potential disease that may occur from high homocysteine levels obtained from meat.

factors that affect b12 absorption

B12 and athletes

With the ever-increasing knowledge surrounding b12 and the synergistic role it plays alongside B6 and folate for regulating energy its important exercise enthusiasts and athletes have a grasp on the effects that strenuous workouts may have on the body

All exercise requires high amounts of energy to be performed effectively and current research suggests that high energy output increases the b vitamin requirements.

Some people may assume taking extra b12 will give them an energy boost allowing them to perform better, but It’s important to remember that b vitamins especially b12 don’t increase energy if you have a sufficient amount, but the key thing is to make sure you have the required amount for your body to run as effectively as possible.

For those limiting calories by being on a cut or those with an unbalanced diet, the effects of a b12 deficiency may be more prevalent.

Although no studies are suggesting that extra b12 will have a negative effect the key take away for vegan fitness enthusiasts or athletes is to keep your vitamin b levels topped up to the minimum RDA to prevent any chance of deficiency since this can potentially affect your energy output and affect your performance in the long run. 


According to the vegan society, B12 is best absorbed in small amounts, so it is more efficient to spread your b12 intake throughout the day in separate meals

Example 1

  • Supplement in the morning
  • Nutritional yeast sprinkled on a vegan pizza at lunch/dinner

Example 2

  • Fortified cereal with soy milk
  • A vegan protein shake mixed with fortified almond milk

Symptoms of vitamin b12 deficiency to look out for

How risky can it be in the long run if my body can produce b12 itself? Well, most of the symptoms that appear due to a deficiency in vitamin b12 appear gradually and stem from the fact that the red blood cells that you need for your body to run efficiently are not being produced at an optimal and healthy rate. It may be a while before the actual effects are prevalent enough for you to feel the need to take action, but do we really want to wait until that point is reached before making sure our health is covered? Some of the early symptoms that appear include

signs of b12 deficiency
  • Memory loss
  • Fatigue
  • Nerve problems or nervous system issues
  • Mood swings
  • Low energy
  • Headaches 
  • Weight loss due to a loss of appetite

With the amount of evidence linked to b12 importance but inefficient absorbability, it may be a good idea to aim for the higher amounts of b12 as recommended here.

You can find out if you are deficient by consulting your doctor and getting a blood test done.

Can you have too much b12?

  • Even considering the recommended daily amount, it is important to remember that our bodies aren’t able to absorb 100% of the b12 when consumed with around 10-20% being utilized, and the rest is excreted. 
  • Remember that the RDA is based on covering the minimum amount a person may need to avoid deficiency, but in many cases, this may not be enough. There is no current evidence to show that consuming more than the RDA is harmful, with studies showing no significant downside with even 10x the RDA. Find reference!!!

So what are the solutions to the vegan b12 situation

B12 fortified foods

One of the first things any vegan can do to start covering any b12 deficiencies is to consume fortified foods that contain b12 such as

  • Nut milk (almond, cashew, hazelnut, coconut milk, etc.)
  • Soy milk
  • Fortified cereals
  • Nutritional yeast

B12 supplementation


B12 supplementation can get confusing since the mcg dose is in the 1000s yet the average RDA is around 2.4mcg. This is because the more b12 you consume in one go the less you absorb. According to the vegan society, 1mcg of b12 will have an average of 50% absorption whereas doses of 1000 or more tend to have absorption rates of around 0.5%

500mcg daily or a 2000-3000mcg weekly supplement is generally recommended.

Some Algae such as chlorella and spirulina contain vitamin b12 as well as being high in a host of other vitamins and minerals. Consuming this regularly in a powder form can also help boost your b12 needs to a degree. The downside to an algae powder is the difficulty in knowing how much b12 you are getting each time you use it plus the mess that can occur with having to mix the powder with water. The plus side is that you can always throw it into a smoothie, which is a great way to boost the number of nutrients your favorite morning smoothie contains.

Overall the best and easiest solution for any vegan regarding b12 is to complement your diet in some way shape or form with either fortified foods or a high-quality b12 supplement, allowing you to get a concentrated and measured amount of b12 in doses that can easily be managed.

Check out our best vegan b12 supplements to find one that works best for you.


Humans are adaptable ever-evolving species that can thrive in many ways. Your decisions regarding health will ultimately come down to what you feel works best for your current value system. We at vegan agility value longevity of life and a thriving environmental landscape, so our food choices are based on what research has shown, is optimal for those ideals. Overall we feel no matter what diet you choose to follow, B12 is an essential part of any diet, and knowing the best way to get the optimum amounts is crucial to the success of your long term health. 

This is easily done by having a regular vegan b12 supplement in our right hand, and some fortified foods on the left, leaving us protected from all angles.

This can be in the form of cereals/nutritional yeast or nut milk and juices. As long as you consume a minimum of 2.4 mcg, daily b12 shouldn’t pose any issues, and you can live happily knowing you have all the other benefits that come from a plant-based diet.


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