The Truth About Vitamin B12 Deficiency

Vitamin B12 (cyanocobalamin) is an essential micronutrient for the wellbeing of body and mind. It participates in the production of DNA and the development of red blood cells, in addition to helping various enzymes exercise their functions in cellular metabolism. It is present in foods of animal origin, mainly meat, but also in milk, eggs, and some fermented foods. Because its source is limited, there is quite a bit of controversy when it comes to Vitamin B12 deficiency and getting enough of this important nutrient. So what’s the truth? Is it true that strict vegetarians and vegans, who avoid most of the foods containing Vitamin B12, have a poor diet? And is it true that carnivores get enough Vitamin B12? Let’s examine this subject with the help of studies that report what is myth or truth on the subject.

Does every meat-eater get enough B12?

No, they don’t.

First, let’s dispel this notion that whether or not you consume animal products is going to solve a Vitamin B12 deficiency issue. Nutrition goes far beyond what we eat. It is vital that the body be able to absorb and use the nutrients it consumes properly. If your body isn’t working properly at any stage of the process, even if you are ingesting huge amounts of a micronutrient, the serum level (amount of the substance in the blood) or level in the tissue or cells can still be deficient.

When a person presents signs of depression, one of the first tests requested by the doctor is precisely that of B12 levels, as this disease is one of the signs of Vitamin B12 deficiency. It is curious that the percentage of depressed individuals is actually higher in groups that consume meat and animal products. A study carried out in Puerto Rico divided 80 people into two groups. The results reported more anxiety and depression in the omnivorous group compared to the vegetarian group.

Does every vegetarian have a B12 deficiency?

This is also a myth.

As noted above, not all instances of B12 deficiency are due to low intake. When the body uses this nutrient in excess (during pregnancy, for example) or increases excretion (as happens with alcoholism) or destruction, the nutrient levels also drop.

In addition to factors that interfere with your absorption and storage of the B12 vitamin and how your body uses that storage, the strictness of your diet will make a difference. For example, if you are an ovolactovegetarian–you consume milk and eggs–you will theoretically have enough Vitamin B12 (we need a small, but important, amount). If you develop a deficiency of this micronutrient it will be for the same reasons as omnivores do, something is preventing proper absorption. There’s no need to blame your vegetarian diet for it.

If you don’t consume milk or eggs, know that a study with Iranians who did not develop B12 deficiency found that these individuals grew their vegetables with human compost (the body produces B12 in the colon, but after the absorption site, so human feces are a source of this micronutrient, which was passed to the plants). Vegetables were consumed after being washed carefully and the amount retained was adequate to prevent deficiencies. I am not recommending you do the same, there are risks of developing bacterial or parasitic infections, but I find it interesting to know these facts. Studies performed with seaweed suggest a more comfortable intake. Let’s have a look.

Is it possible for vegans to consume enough B12 without supplements?


Dr. Bonny Specker and his collaborators in the USA evaluated several foods and found that certain marine vegetables, such as wakame and kombu, contained B12 at a level similar to that of cow liver. Similarly, a study in Finland with long-standing strict vegetarians found that those who consumed certain seaweed had B12 concentrations twice as high as those who did not.

Does lifestyle impact levels of B12?


I recently watched a documentary that gathers a series of articles and addresses this subject. The documentary is “The Game Changers” on Netflix. Have you watched it? It impacted me as a nutritionist and made me even more eager to research this topic. If we think about it from a historical point of view, how come there were many vegans throughout history who never needed B12 supplementation, and today many people do? Throughout the world, there has been a change in culture, in the way we cultivate our food, in our lifestyle, and so on. Today pesticides, chlorine, and antibiotics kill the bacteria that we need, and that animals need too. If there are no bacteria in the soil and in the water, animals, like us, will also not have enough B12, which is why many animals have Vitamin B12 added to their feed.

Do I need to take vitamin B12 supplements or not?

If your reality is a city-life with a less than an ideal diet, your chances of experiencing a Vitamin B12 deficiency are higher, regardless of whether you eat meat or not. It’s worth having a check-up with your nutritionist. If this investment isn’t possible at the moment, your diet is restricted, or you are experiencing any of the signs below, it may be interesting to use supplements.

Clinical signs of vitamin B12 deficiency

It is important to remember that vitamin B12 deficiency can be asymptomatic and occur for long periods before the appearance of any clinical signs or symptoms. Also, remember that some cases are mild, others more severe. This list isn’t meant to scare you, but to raise awareness.

Symptoms are fatigue, weakness, constipation, loss of appetite, weight loss, numbness and tingling in the hands and feet, difficulty maintaining balance, depression, confusion, dementia, lack of memory, and pain in the mouth or tongue.

What can I do? Start at the beginning:

  1. Choose to invest your money in the best foods: fruits, vegetables, legumes, cereals, and nuts. Your microbiota thank you!;
  2. Chew your food as if it were the last bite of your life (eating is good!);
  3. Don’t stress, your stomach thanks you and provides the intrinsic factor that activates B12 (IMPORTANT).

Share this article with that friend who is also curious about Vitamin B12 and bookmark it for the next time someone questions your vegetarian lifestyle with “What about Vitamin B12?”.


NAVARRO, Julio César Acosta. Vegetarianism and science: a medical point of view on meatless eating. São Paulo: Alaúde Editoral, 2010. p. 28-34.

PANIZI, C .; GROTTOII, D .; SCHMITT, G.C .; VALENTIN, J .; SCHOTT, K. L .; POMBLUM, V. J.; GARCIA, S. C. Pathophysiology of vitamin B12 deficiency and its laboratory diagnosis. J. Bras. Patol. Med. Lab. Vol.41 no.5 Rio de Janeiro Oct. 2005. Available at: Accessed on March 29, 2020.

PAWLAK, R .; LESTER, S .; BABATUNDE, T. The prevalence of cobalamin deficiency among vegetarians assessed by serum vitamin B12: a literature review. Eur J Clin Nutr 68, 541-548 (2014). Available at: Accessed on March 29, 2020.


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