Symptoms warning of vitamin B12 deficiency in the body

Red Meat - B12 Vitamin

Vitamin B12 plays an essential role in human health and its deficiency can cause certain damage to the body. In this article, we will show you what the symptoms are, what causes it, what problems it causes in the body, and how to prevent vitamin B12 deficiency.

Vitamin B12 is one of the most important nutrients for the health of the body, although it has the peculiarity of being found only naturally in animal foods. This vitamin is essential for the health of neurons and blood, among its many health functions.

There are a total of 13 vitamins essential for the growth and proper functioning of the human organism, and more than half of them belong to the group of B vitamins. Some of them have different names since they are also known by their number. The best known are vitamin B1 or thiamine, B2 or riboflavin, B3 or niacin, B6 or pyridoxine, B9 or folic acid, and B12 or cobalamin. Thus, people with B12 deficiency can develop dangerous health conditions, with the particular incidence of a type of anemia known as megaloblastic anemia.

Specifically, vitamin B12 is involved in the formation of deoxyribonucleic acid, which is the genetic material present in all the cells of the organism. Likewise, this vitamin is essential for the brain to transmit nerve messages to other areas of the body.

What are the symptoms of vitamin B12 deficiency?

  • Tingling sensation in the body (paresthesias).
  • Lack of coordination and slowness of reflexes.
  • Cognitive problems (mental confusion and memory impairment).
  • Gastrointestinal symptoms such as canker sores or mouth ulcers, loss of appetite, diarrhea, or constipation.
  • Pale or yellowish skin (jaundice).
  • Weakness, fatigue, tiredness and shortness of breath.
  • Dizziness and blurred vision.

Most common causes of vitamin B12 deficiency

  • Pernicious anemia is the most common cause of megaloblastic anemia and vitamin B12 deficiency and is due to an inability of the body to absorb this vitamin due to a decrease or absence of a protein called intrinsic factor.
  • Either by atrophy of the gastric mucosa or by the destruction of the parietal cells of the stomach that produce it caused by an autoimmune disease such as celiac disease, Addison’s disease, Crohn’s disease, Graves’ disease, type 1 diabetes mellitus, Myasthenia gravis, Sjögren’s syndrome or vitiligo.
  • Poor absorption of vitamin B12 together with food, certain drugs such as antacids, antibiotics, antihypertensives, antiepileptics, etc., or excessive consumption of coffee.
  • A strict vegetarian diet, Helicobacter pylori infection, and advanced age, as a comorbidity of any of the causes mentioned above, can also lead to cobalamin deficiency.

Vitamin B12 deficiency problems

Some people have a greater tendency to have deficient levels of vitamin B12 in the body. This is especially true for people over 50 years of age, people who follow a vegan or vegetarian diet, or people with some type of digestive problem that prevents a correct absorption of this nutrient.

In any case, it is important to prevent the lack of B12 in the organism, since its deficiency is related to different health problems. Likewise, in case a blood test shows a deficiency of this nutrient, it is necessary to establish a treatment to return to optimal levels.

The main consequence of vitamin B12 deficiency is megaloblastic anemia, characterized by symptoms of weakness, tiredness, pale skin, palpitations, loss of appetite, or weight loss. Likewise, the lack of this nutrient can also affect the nervous system, even in people who do not develop this type of anemia.

It should not be forgotten that B12 is also related to neuronal health. In this sense, the lack of this nutrient can lead to memory loss, depression, confusion, dementia, and loss of balance.

Where is Vitamin B12 present?

B12 is a vitamin that is only found naturally in foods of animal origin, with the exception of some plants to which its presence is attributed in minimal quantities. The body does not have the capacity to produce this vitamin by itself, so it is essential to incorporate this vitamin through food.

It is also possible to increase vitamin B12 levels by treatment with vitamin supplements. However, this option is only recommended if indicated by a medical specialist under specific guidelines.

Thus, the main foods that provide the body with vitamin B12 are meat, fish, sausages, seafood, eggs, and dairy products. Therefore, people who follow a balanced and healthy diet do not usually have problems due to deficiency of this vitamin.

Foods high in vitamin B12

As we have argued above, in order to have optimal levels of B12 in the body, it is essential to follow a balanced and healthy diet, which allows the regular incorporation of foods of animal origin.

Thus, these are some of the foods that provide the greatest amount of vitamin B12:



Meat in general (beef, pork, chicken, lamb…) is one of the main sources of vitamin B12, hence people who follow a vegetarian or vegan diet, who do not eat this type of food, have to periodically monitor the levels of this vitamin in their organism in view of the possibility of having to supplement their diet with vitamin B12 supplements.

Practically any meat is able to provide us with vitamin B12, but one of the richest in the content of this one is the lamb meat with 2,62ug (milligrams) by every 100 grams and next they are the veal meat, around 1ug/100, and the pork meat with 0,6ug/100 grams. Of course, as several published studies show, these quantities vary according to the piece of meat in question, but they undoubtedly point to this food as an unquestionable source of this valuable vitamin.



If the meat from animals contains a considerable amount of vitamins of the B group and, specifically, of B12, the livers of certain animals are their best kept ‘treasure’, because, for example, 100 grams of beef or ox liver (raw) provide 81ug and if we talk about the chicken liver, with which you can make delicious recipes, its content is the not inconsiderable amount of 25ug of vitamin B12 per 100 grams.



Some foods that the sea gives us are also an excellent option to provide the body with that essential nutrient that strengthens the immune system, enjoying, in addition, the exquisite taste of seafood.

Bivalves (mollusks that have a shell composed of two halves) are the most interesting source, since 100 grams of oysters can provide up to 16.5 ug, and the same amount of mussels can give us a total of 8 ug of vitamin B12. For their part, raw clams contain only traces of this vitamin, but canned clams are a source to be taken into account since they provide up to 5 ug/100 g.

Oily fish


We know the beneficial properties of oily fish, which is especially healthy for our cardiovascular system due to its high content of healthy fatty acids, such as Omega 3. In addition to taking care of our heart, fish such as salmon, tuna or sardines provide significant amounts of vitamin B12. An excellent 100-gram slice of grilled salmon will provide your body with 4 grams of the vitamin, and if you like tuna more, you should know that it contains the same amount. On the other hand, 100 grams of sardines will ingest more than twice as much, that is, about 8.5 g/100 grams.



Following the vitamin contribution that we can obtain from foods from the seas and oceans, squid and cuttlefish with 2.5 g of vitamin B12 per 100 g of food are the best. The octopus surpasses them, concretely with about 3ug of vitamin B12 for each 100g of octopus, but it must be taken into account that during the cooking it loses practically the totality of the vitamin that it contains.



Eggs contain in their whites and yolks all the essential amino acids that the body needs together with proteins of high biological value, which is why it is considered by many people as a superfood. As if all this were not enough, egg yolk is also rich in vitamin B12, providing 4.7 grams of vitamin B12 per 100 grams.

Dairy products


Although not in large quantities, whole cow’s milk also provides vitamin B12, specifically 0.3ug of vitamin B12 per 100 g of this food. On the other hand, some of its derivatives, mainly certain types of cheese, are a source to take into account when it comes to ingesting this nutrient that we need on a daily basis. At the top of the ranking of cheeses that contain the most vitamin B12 are two: Emmental cheese with 2.2 grams of this vitamin per 100 grams and Parmesan cheese with 1.5 grams of this vitamin per 100 grams.

To avoid the lack of this vitamin in our organism, it is necessary to know how to ingest vitamin B12 according to the recommended dosage:


  • 0 to 6 months: 0.4 mcg/day
  • 7 to 12 months : 0.5 mcg/day


  • 1 to 3 years: 0.9 mcg/day
  • 4 to 8 years: 1.2 mcg/day
  • 9 to 13 years: 1.8 mcg/day

Teenagers and adults

  • 14 years of age and older: 2.4 mcg/day
  • Pregnant women: 2.6 mcg/day
  • Breastfeeding women: 2.8 mcg/day

It should be noted that in addition to food, we can consume vitamin B12 supplements if a doctor has suggested it to us. This vitamin comes in capsule form, you can take it as an injection or in sublingual format, which dissolves under the tongue. Additionally, your body will absorb the supplement better if you combine it with other B vitamins or magnesium.

Never take supplements without first consulting your doctor.


Vitamin B12 is naturally present only in foods of animal origin, such as meat, fish, eggs, milk, and dairy products.

In the case of vegans, who eat only plant-based products, foods enriched with cobalamin (vegetable kinds of milk, certain soy products, and some cereals) are the best way to prevent a deficiency of this vitamin.

Also without forgetting nutritional supplements, which should also be considered for vegetarians, who feed on products of vegetable origin, dairy products, and eggs.

Other types of vegans and flexible vegetarians, who although they opt for a diet of vegetable origin, which also includes dairy products and eggs, do not shy away from occasionally consuming some meat and fish.

In general, people who follow a varied diet do not usually have problems having optimal values of this vitamin in the body.

Rate this post

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top