Vitamin B12 and vegans: Are animal products reliable sources?


In this article, I will continue with intriguing vitamin B12 and vegan topic. In the previous post, I gave a quick intro to the vitamin. Today, I will deviate a bit from plant foods and look at animal-derived foods.

Vitamin B12 and vegan - Are animal products reliable sources - cowsIt almost became a common knowledge that animal products are reliable sources of vitamin B12. Are they?

According to studies, yes, they are. Then, logically, those who eat meat, dairy and eggs should have sufficient levels of vitamin B12 in their bodies. However, numerous studies demonstrate that Vitamin B12 deficiency happens in these people as well.



Why is there so much fuss specifically about vegans who are deficient in B12 then?


I think there are several reasons behind this.

First, because animal foods have naturally-existing vitamin B12 in them they might be better sources than plant foods. Plant foods contain B12 only if they somehow contaminated with B12-producing bacteria.

Here is the summary of how animal products naturally contain vitamin B12:

In animals, including humans, B12 is synthesized by bacteria found in the intestines. Then vitamin B12 is transferred to a liver. Once Vitamin B12 is in a liver, it gets distributed to cells of different tissues like muscles and lungs. Therefore, when you eat a cow liver or meat (muscles), you should get vitamin B12 because it is already there. In case of seafood such as oysters, you eat an entire animal including digestive tract. As I mentioned in the last article, digestive tract is precisely where vitamin B12 is made, so by eating a whole oyster you should get even more vitamin B12.

In contrast, plants do not contain vitamin B12 on their own. Basically, the only way to get vitamin B12 from plants is to leave them slightly unwashed. For example, a freshly picked carrot or beet with traces of soil on them would give you vitamin B12. In soil, B12-producing bacteria likes to hang out around the roots of plants.

Second reason in short. Meat and dairy industry needs to make money. Through media it makes it seem like beef is the only source of vitamin B12 on the planet and you better swallow a hamburger.

Now, getting to the most interesting part.

If animal-derived foods contain vitamin B12 then why doctors often see low levels of B12 in blood of those who do eat meat?

There are multiple reasons for low vitamin B12 in blood of those who eat meat, dairy and eggs. I will touch the most important ones.



Reasons for low vitamin B12 in those who eat animal products



Vitamin B12 is damaged by heat.

I bet that you eat your meat and eggs thoroughly cooked. In case of milk and cheese you buy in store, they are always pasteurized, no exceptions here. As a matter of fact, in Canada and most US states, it is illegal to sell raw milk. This is a problem because B12 is partly destroyed by heat. Depending on the food and the way it is cooked as much as 45% of original vitamin B12 disappears. Even before you put it in your mouth, so forget about it being in the blood!



Vitamin B12 does not do well in acidic conditions.

In order to better digest protein coming from meat, you need a highly acidic environment. To accommodate this, your parietal cells need to secrete more hydrochloric acid. Parietal cells are located in your stomach lining and their task is to secrete hydrochloric acid every time you eat a meal. More hydrochloric acid in your stomach creates enough acidity for a better digestion of meat.

Okay, the goal is reached, meat is now better digested. However, high acidity is detrimental for vitamin B12! It means that vitamin B12 is damaged in your stomach before it even moves into the intestines. Intestines, there are two of them, large intestine and small intestine, is where nutrients, including vitamin B12, leave you gut and enter your bloodstream (absorption). No wonder doctors don’t see a lot of vitamin B12 in blood!


Vitamin B12 and vegan - Are animal products reliable sources - acidity


The extent of absorption

Your body does not do a good job at absorbing Vitamin B12.

The saying, you are what you eat, did not appear out of the thin air. However, you are what you absorb is a more correct version of it. No matter how healthy the food you put in your mouth is, if you are bad at absorbing this food, there is little benefit to it. Again, absorption takes place when nutrients leave your intestines (mostly small intestine though) and enter your bloodstream. Once the nutrients in the blood they can be distributed to cells of different tissues in your body which is a final goal. Similarly, if you are not good at absorbing vitamin B12, all that hard work trying to get more of it is completely wasted.

There are tons of factors that affect the absorption of Vitamin B12, or, in other words, how much of it enters your blood. I will discuss two major ones.


The extent of absorption: antibiotics

Vitamin B12 and vegan - Are animal products reliable sources - friendly bacteria

Friendly bacteria (in green) in the small intestine.

Let’s take a look at the common one, antibiotics. Antibiotics indirectly lower the amount of vitamin B12 you absorb.

That includes both – the ones you take and those already present in conventional meat and dairy. If you don’t know yet, antibiotics are added to milk so that it does not spoil forever. All right, maybe not forever but for three weeks for sure. Antibiotics literally means killing lives, and they do kill lives, little lives of friendly bacteria in your gut.

Friendly bacteria helps a lot in moving vitamin B12 from your small intestine into the blood. If your body is full of antibiotics, friendly bacteria does not do well and thus cannot help you move a lot of Vitamin B12 into the blood.

Sadly, in those who eat meat, this friendly bacteria is also damaged by the constant putrefaction process in the large intestine. Putrefaction is a process of decomposition, in this case, decomposition of undigested meat. There is undigested meat in the first place because animal protein such as meat is only partly digested by humans!


The extent of absorption: Intrinsic Factor

Another major thing that determines how much of vitamin B12 gets absorbed is presence of Intrinsic Factor.

Similar to hydrochloric acid, Intrinsic Factor is released by parietal cells after you eat a meal.  It is an enzyme and it has only one job – transfer vitamin B12 through acidic environment in the stomach into the small intestine. If parietal cells are damaged, they release little or no Intrinsic Factor. This means that very little of Vitamin B12 is safely moved from the stomach into the small intestine and thus very little enters the bloodstream.

Bear in mind that because Intrinsic Factor can only do so much in terms of protecting Vitamin B12 from stomach acidity, the above-mentioned elevated acidity in those who eat meat still damages vitamin B12.






The conclusion that can be made from the above is that animal foods are reliable sources of B12 and studies are correct.

However, authors of these studies need to do a bit of extra work and look at the most important point: how much of vitamin B12 actually enters the bloodstream of an average person after they eat a cooked piece of meat. Enters the bloodstream and actually gets distributed to the cells!

I think they will be surprised at the results. Without a shadow of a doubt, they will see less of it in blood!



What can be done so that good amounts of vitamin B12 actually enter the bloodstream? And how raw vegans can do it?

This will come in the next article, so don’t miss it!

Do you think differently about animal products and vitamin B12? Did this article help you in some way? Let me know by leaving a comment below. Thanks!





Main references:

Kim., E., Coelho D., Blachier F. (2013). Review of the association between meat consumption and risk of colorectal cancer. Nutrition Research, 2033(12): 983-994


  1. Thank you for writing this concise and simple-to-understand article. I never know vitamin B12 can be soo hard to get. I always thought vegetables and fruits has all the vitamins we need but it is not the case with B12 it seems. It is also shocking to know that the net amount of B12 we absorb from meat is very little due to heating from cooking and absorption issues.

    What do you think we can do to increase B12 in our body?

    • Hi Isaac,

      Yes, tomatoes and apples don’t have B12 in their flesh. But if you harvest them from your own garden (or buy them from farmers who you trust) and eat them slightly unwashed with some soil left on them, then your B12 will never be low. There is lots of B12-making bacteria in the soil.

      Read Vitamin B12 and vegans: How to get vitamin B12 article if you want to pump on some vitamin B12, whether you are vegan or not.

  2. Hi Margarita! I’ve read the next part of this article and really benefited from it. Many thanks =)

    Even though it’s good, somehow I can’t bring myself to eat a soil… The supplement is the way to go for me . Do you know any other vitamins or minerals that is as hard to be obtained like the B12?

    • I see. Make sure the supplement is of good quality, at least.

      Are you vegan? Usually vegans are exposed to less vitamin K2(menaquinone), vitamin D and vitamin A as these are mostly found in animal and fish organs and meats. However, B12 is the only vitamin that’s seems to be missing in plant tissues (research studies are not conclusive). There is lots of B12 analogs though – seaweed, mushrooms. Whether B12 analogs are as good as the real vitamin B12 is not known. More research is needed.

      As far as I know, vegans in terms of minerals, are in good shape.

      Soil, if it is from your backyard, is not that bad though. Just a little bit annoying to feel it on your teeth, that’s all!

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