Vegan Vitamin B12 – Sources, Absorption, Supplements and Deficiency

Vegan Vitamin B12

Vitamin B12, also known as cobalamin, is one of the thirteen essential vitamins that the body requires to survive. It is involved in many crucial processes, including (1) creating DNA, cell division and, maintaining and repairing Myelin Sheath (a protective coating around nerve cells). Unfortunately, there are limited vegan vitamin B12 sources as plant based foods do not naturally contain this vitamin. 

Animal products including meat, chicken, fish, eggs and dairy products are rich in this vitamin.

Consuming enough B12 is crucial for proper blood and brain function and it can be stored in the liver for many years. Deficiency can lead to a range of health consequences including nerve damage and pernicious anaemia. 

It is important for those following a vegan or vegetarian diet ensure they are getting enough each day through foods or supplements.

This article explores vitamin b12 on a vegan diet, where you can find it, supplement recommendations and how to avoid deficiency.

What does Vitamin B12 Do In The Body?

Vitamin B12 is an essential nutrient that almost every cell in the body requires for proper functioning. It is involved in two main biochemical processes in the body and acts in two main forms – methylcobalamin and adenosylcobalamin. Each of these forms have a different role.

Methylcobalamin acts as a cofactor to the enzyme methionine synthase, which catalyses the transfer of a methyl group from N-methyltetrahydrofolate to homocysteine, yielding methionine and tetrahydrofolate. This reaction occurs in the cell cytoplasm (2).

From methionine, S-adenosyl-methionine is formed, which is a universal methyl donor for many important substrates, including DNA, RNA, hormones, proteins, and lipids. This reaction is also important as it converts methyltetrahydrofolate to tetrahydrofolate, the active form of folate, which is another essential B-vitamin.⁠

Adenosyl cobalamin acts as a cofactor in the methyl-malonyl CoA mutase transformation of methyl-malonyl CoA into succinyl CoA in the mitochondria (2). ⁠

How is it absorbed?

The absorption of vitamin B12 contains a number of steps.

In animal based foods, it is found in the form of methyl-, deooxyadenosyl-, or hydroxy-cobalamin.

When this form of B12 nutrition reaches the stomach, two digestive enzymes – pepsin and hydrochloric acid break down the binding protein, releasing the cobalamin portion of the nutrient known as “free vitamin b12”.

When synthetic (man made) B12 is added to fortified food or supplements, it is already in its free form and therefore does not require this separation step.

Free vitamin b12 then combines with Intrinsic Factor (IF). IF is a type of protein secreted by parietal cells in stomach. This complex is then able to be absorbed in final section of the small intestine known as the illeum.

Absorption can also be influenced by age, reduced gastric acidity and other gut disorders.

This vitamin also has many inactive analogues. These are molecules that look like its active form, but actually are not, and can interfere with it’s function and absorption.

How much vitamin B12 can be absorbed at once?

Vitamin B12 absorption depends on how much is consumed at one time. When added to foods such as soy milk or veggie delight sausages in low amounts (less than 5 mcg per dose) it has a similar absorption rate to animal products. It is absorbed at approximately 56% of a 1mg dose.

Meaning, if you drank a glass of Sanitarium So Good Soy milk which contains 1mcg per cup, you would only be able to absorb approximately 0.5mcg.

Some brands of plant based milk are fortified with vitamin B12

 

However, absorption decreases significantly with high doses of B12. Doses above 500mcg have absorption of 1% or less.

This means, that if you take a supplement of 500mcg, you’re only able to absorb 5mcg at one time.

How Much Vitamin B12 Do I Need?

How much you require each day is based on the Recommended Daily Intake (RDI). The RDI is the average daily dietary intake that meets the nutrient needs of 97-98% of the population.

A summary of the  RDI for vitamin B12 based on the Nutrition Reference Values for Australia and New Zealand (2):

For children under 12 months of age the RDI cannot be determined and therefore Adequate Intake (AI) is used.  The AI is based on the average daily nutrient intake deemed to be adequate based on estimates of healthy groups.

The nutrient reference values (NRVs) for Infants is measured by adequate intake (AI) and is outlined above (2):

Vegan Vitamin B12 Food Sources:

Our bodies can not create B12, meaning that it must be eaten in the diet. 

Vitamin B12 is bound to protein. It is found in all animal foods with the exception of honey.  This includes meat, poultry, fish, eggs and dairy products (3).

Individuals who follow plant-based diets must rely on fortified foods and supplements to meet their daily requirements.

Vegan vitamin B12 food sources include:

  • Certain plant-based milks (i.e. Sanitarium soy milk)
  • Nutritional yeast
  • Reduced salt Vegemite (note: the original vegemite is not fortified with B12)
  • Certain meat substitutes (i.e. Vegie Delights products)

If you are wanting to meet your daily needs through fortified foods it is essential that you read the ingredients list and nutritional panel as not all products listed above will be fortified with this nutrient.

Products fortified with vitamin B12 will have this listed on the nutrition panel

It is also important to note that nutritional yeast, also known as savoury yeast flakes, may not be a reliable source. The vitamin levels contained within nutritional yeast can vary between brands, meaning it is not recommended as a sole source B12.

The table above outlines the vegetarian and vegan vitamin B12 food sources (4):

If you want to try and meet your requirements through food alone you will need to consume 2-3 servings of fortified foods, at least 4 hours apart for optimal absorption. 

The number of servings required daily will vary depending on which fortified products you consume. Due to this not being feasible for many individuals, it may be beneficial to consider a vegan vitamin b12 supplement.

Poor Sources of Vitamin B12

Some vegan foods claim that they contain B12. This includes tempeh, seaweed, organic foods and spirulina. Unfortunately these contain inactive analogues. This means, when analysing these compounds in the lab they may look like vitamin B12, but they are not biologically active meaning humans cannot absorb them. 

Signs of Vitamin B12 Deficiency

Deficiency can be common amongst vegans and those following a mostly plant-based diet. 

Sign of vitamin B12 deficiency include (3):

  • Megaloblastic anemia, meaning red blood cells are not produced properly and are larger than normal
  • Fatigue
  • Weakness
  • Constipation
  • Loss of appetite
  • Weight loss
  • Numbness
  • Tingling of the hands and feet

Signs of deficiency in infants include (7):

  • Failure to thrive
  • Movement disorders
  • Developmental delays
  • Megaloblastic anemia

A 2013 systematic review investigating the prevalence of deficiency among vegetarians and found rates of 62% amongst pregnant women; 32% amongst vegetarians; and 30% to 76% amongst vegans (depending on the definition of deficiency) (6) 

Normally, anaemia is the first symptom of deficiency to occur. Often deficiency can go undetected in vegans as it is masked by high intakes of folate, found in fruits, vegetables and wholegrains (3). If someone’s diet is high in folate and low in B12, the folate will “mask” the anemia and nerve damage will be the first symptom to occur.

Although textbooks and articles state that deficiency can take 2-5 years, our dietitians have seen deficiency occur in as little as 6 months. It is essential to commence supplementation or ensure you are eating adequate amounts as soon as you adopt a completely plant based diet

It is also important for plant-based eaters to regularly check their blood status. Failure to do so can increase the risk of irreversible brain and nerve damage. 

Should vegans supplement Vitamin B12?

Even though there are some plant-based foods fortified with B12, the selection is quite limited and these foods need to be consumed daily to meet the RDI. 

For this reason it is often recommended that those that follow a largely plant-based diet, consider taking vegan Vitamin B12 supplements. 

To work out an appropriate supplement regime for you, book in for a consultation with one of Plant Nutrition and Wellness’s plant-based dietitians

 

 

References

(1)  The Medical Journal of Australia – Vitamin B12 and Vegetarian Diets

(2)  Nutrient Reference Values – Vitamin B12

(3)  National Institute of Health – Vitamin B12

(4)   Food Standards Australia New Zealand. NUTTAB 2010 online searchable database

(5)  https://vegemite.com.au/product/

(6)  How prevalent is Vitamin B12 deficiency among vegetarians?

(7)  Homocysteine and methylmalonic acid in diagnosis and risk assessment from infancy to adolescent

(8) Biochemistry of B12-Cofactors in Human Metabolism 

 

This article was co-written by Plant Nutrition and Wellness’s founder Kiah Paetz and Intern Tessa Funk. You can connect with Tessa on linkedin here.

Do Vegans Need To Use Protein Powder?

One of the most common questions asked to people following a vegan diet is “where do you get your protein from?”. Understandably, this can be incredibly frustrating and may even leave you double-guessing whether or not you are consuming enough. In this article, we explore some sources of plant-based protein and ask the question – do vegans need to use protein powder?

What is protein? 

Protein is a key nutrient in the human body, it is responsible for muscle maintenance, key regulatory systems like hormone production, wound healing and fighting infection [1] It is also a bit of a nutrition ‘buzz-word’, due to all of the fitness influencers on social media.

What are sources of plant based proteins?

The main sources of vegan protein include (but are not limited to); legumes (including beans, peas, lentils and pulses), nuts and seeds (including pastes, butters etc), tofu, tempeh, quinoa and of course protein powders. These vary in protein content from about 5g per serve to 14g per serve [2].

Serve size is dependent on the type of protein source, for example, one serve legumes is equal to 1 cup vs 1 serve of nuts, which is equal to only 30g (a small handful) [3].

It is important to note here that on social media you are likely to find a lot of information about protein content comparisons of foods “per 100 calories”. Though this information may not be incorrect, it has been taken out of context and therefore can be quite misleading.

For example, it is misleading to say that 100 calories of broccoli (this is a classic example circulating online) is comparable, in any sense, to 100 calories of meat. Why? Because 100 calories is 2 or more cups of broccoli compared to only a few mouthfuls of meat [2].

What this means is that if you’re trying to be conscious of your protein on a plant-based diet, broccoli is probably not going to be your preferred source unless your would like to have many cups of broccoli every day. I could go on further about why this is misleading, but I think you get the picture.

What if I don’t like vegan proteins like beans?

You could try eating a variety of different protein sources. This will not only ensure you are consuming enough protein, it will also mean that you are obtaining all of the essential amino acids across the day and week,

Amino acids are the smaller components that proteins are made of.  Different sources of protein contain different amino acids[1].

This will also mean that you are less likely to get bored with your protein source. 

Another strategy to up your daily protein intake is to consume a source of protein at every meal.

Having a source of protein at each meal will make sure you are consuming enough protein across the day. Adding protein to a well-balanced meal with some healthy fats, carbohydrates and lots of veggies will also help you stay satiated and full.

To help grow muscle (known as muscle protein synthesis) it is also important to space protein across the day [1]. You can read more on this in our blog article on How to Build Muscle On A Vegan Diet

You might use a protein supplement when: 

1. You are unable to consume enough protein from whole foods.

This might be for a number of reasons, including that you have an allergy or intolerance as discussed above. You might also have increased protein requirements because you are trying to gain weight or because you are an athlete. You might just plain not enjoy plant-based protein sources – which brings me to the next reason we might choose to supplement protein.

2.  You prefer the taste

I don’t know about you, but I personally am not a fan of savoury breakfasts (no offence if you are – you do you!). So if you’re like me and prefer to have a sweeter tasting breakfast, this is where protein powders can really come in handy to get a decent protein hit in the AM. Protein powders can be added to anything – smoothies, oats, as an extra to yoghurt or even just on its own with water or a milk alternative. Adding protein powder is not detrimental to flavours and can actually make your meal even tastier (hello flavoured protein powder in a smoothie!). Try adding some nuts too for some (extra) protein, as well as some healthy fats!

There are no hard rules on how to eat protein. Whether you supplement or not, the main thing is that you are consuming enough of it and spreading it across your day as best you can! If you aren’t sure if you’re eating enough – speak to your dietitian!

 

Looking for more tips on how eat more plant based protein?  Check our our blog on 6 Top Tips for Transitioning to a Vegan Diet

This blog was co-written by PNW Clinic founder Kiah Paetz and student dietitian by Donna Harris. You can connect with Donna on instagram @pepperandcorndietetics.

 

If you’re wanting to take your diet to the next level, and book in to see one of our expert  dietitians.