Do mushrooms contain enough Vitamin B12?

Part of the initiation into a vegan lifestyle is learning about Vitamin B12. Before becoming vegan, you may not have ever heard of Vitamin B12. However, once you graduate to a plant based diet you may learn quickly that Vitamin B12 plays an important role in mood, memory and nerve function and needs to be well considered in a vegan diet. It can also be quite difficult to get enough Vitamin B12 as a vegan.

A black pan on a stove with mushrooms and olive oil.

Do mushrooms contain Vitamin B12? 

Often I read or hear people suggesting that if you eat a lot of mushrooms, you do not need to be concerned about B12. Whilst there is some truth in the mushroom theory, I personally think most of it is just some clever advertising by the mushroom industry - but let’s take a look at the research.

According to the Australian Food Standards, there are no plant based foods that contain Vitamin B12. “But I thought mushrooms contained Vitamin B12?” Whilst this may appear confusing, there is good reason that this is a common understanding. (ref: Food Standards Australia)

Vitamin B12 is not synthesised by animals or plants, but by bacteria  (Watanabe & Bito 2018 p 148). Yep, it is bacteria, like those little organisms in your gut, which create B12.

Therefore, for a food to contain B12 it must contain the B12 synthesising bacteria or have been in contact with this bacteria. Non-vegan forms of B12 come from the bacteria that live inside the animal, and are passed on though the consumption of animal products. 

What about Vitamin B12 in a vegan diet?

Mushrooms that have been found to contain B12 must have been in contact with B12 synthesising bacteria in the soil, suggesting it is not the mushroom that contains the B12, but a source outside the mushroom (Watanabe & Bito 2018 p 148). Thus mushrooms themselves do not contain B12, but if the bacteria is still present on the mushroom at the time of consumption, then you will be consuming Vitamin B12.

Not all mushrooms are grown in areas that contain these bacteria. Research has discovered that the following mushrooms can have B12 present due to their growing conditions: shitake, porcini, black trumpet, golden chanterelle and pleurotus (Watanabe et al Nutrients, 2014p1862) (Rizzo et al, Nutrients, 2016. p676). Unfortunately these mushrooms are either difficult to source, contain too little levels of B12 to be significant or the amount of mushrooms you need to consume each day to get enough Vitamin B12 is almost impossible.

Brown oyster mushrooms growing from the side of an oak tree. 

Can I eat enough mushrooms to get my required Vitamin B12 on a vegan diet?

Below I have included a table that states which mushrooms have been found to contain B12, how much per 100grams and why each one will not be a suitable source to maintain optimal Vitamin B12 levels in a vegan diet.

It is important to note that the recommended daily intake (RDI) for Vitamin B12 is 2.4ug per day. Note: “ug” is the scientific symbol for one millionth of a gram. 

Type of mushroom

B12 content

Per amount

Problem

Shitake Mushroom

3.95-5.61 ug

100g

Good source, but difficult to consume adequate amounts every day.

Porcini Mushroom or Pleurotus Mushroom

0.01-0.09 ug

100g

Not enough to reach recommended daily intake.

Pleurotus mushroom species from Sicily

0.44-1.93 ug

100g

Good source, but research only on mushrooms found in Sicily.

Black Trumpet Mushroom (Mushroom C. cornucopiodes) / Golden Chanterelle Mushroom (Mushroom C. cibarius).

1.09-2.65 ug

100g

Not a common mushroom – hard to source.

So unless you are capable of consuming 100 grams of shitake mushrooms every day, I would be looking to other avenues to find my RDI of Vitamin B12.

Where can I get Vitamin B12 from in a vegan diet?

From my research as a qualified naturopath, I have found the only reliable sources of Vitamin B12 in a vegan diet are from fortified foods such as:

  • Some soy milk brands.
  • Brewer’s yeast.
  • Nutritional yeast flakes.
  • Vegemite and Marmite.
  • Some breakfast cereals.
  • Some vegan meat substitutes.

Note: it all depends on the quality of these foods and how they are fortified that will give you good amounts of B12. Be sure to read the labels!

A jar of vegemite for vitamin b12 and three bananas on a green background.

So, if you are not consciously including foods that are fortified with B12 in your diet, a sublingual (by mouth) Vitamin B12 spray should be considered.

Using a practitioner recommended B12 spray will assist with keeping your B12 levels at the right amount for living a healthy vegan life. If you would like more information on where to find a good quality Vitamin B12 spray please feel free to email me: walkingnaturespath@gmail.com 

x Tara 

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