It is estimated that approximately one in eight people over the age of 50 is deficient in vitamin B12. Strict vegetarians of all ages are at an increased risk of chronic deficiency of this micronutrient.
Vitamin B12 (cobalamin) is found almost exclusively in animal products: meat, fish, dairy products, eggs. Strict vegetarians who do not consume such products should not forget to periodically take this vitamin in the form of supplements or fortified foods.
Vitamin B12 is needed for the production of red blood cells (erythrocytes). Erythrocytes, in turn, are needed to transport oxygen in the blood.
In addition, vitamin B12 is necessary for the proper functioning of the nervous system.
Together with folic acid (vitamin B11) B12 is responsible for the synthesis of DNA and RNA. Activation of folic acid in our body depends on the presence of B12. That is, B12 deficiency can lead to folic acid deficiency.
How much B12 do we need
B12 is the only water-soluble vitamin that our body can accumulate and store for a long time. Our liver has a supply of B12 of about 2-5 milligrams. At first glance, this is not much. But the recommended daily allowance of vitamin B12 for women and men aged 19 and above is only 2.8 micrograms. This amount is comparable to the weight of the ink at the point at the end of this sentence!
So, the stock in the liver may be enough for 2-5 years, on average for three years. Individuals who have completely excluded all animal foods from their diet, may survive on their B12 supply for years before they develop deficiency symptoms.
How the body absorbs B12
B12 deficiency is a fairly common phenomenon, also among carnivores. How come? Deficiency of this vitamin most often occurs not due to its lack in the diet, but due to impaired absorption.
Here is a brief summary of how the absorption process occurs. B12 from food is released in the stomach under the action of hydrochloric acid and the enzyme pepsin. Further in the small intestine B12 connects with the so-called intrinsic factor and travels with it to the end of the small intestine (Ileum). There, special receptors recognize vitamin B12 (but only if it is in the company of the intrinsic factor!), after which the gradual absorption of vitamin B12 into the blood begins.
Causes of vitamin B12 deficiency
The most common cause of vitamin B12 deficiency is inadequate absorption. The following conditions influence the absorption:
- Inflammatory bowel disease affecting the last part of the small intestine
- Bariatric surgery for weight loss
- Surgery that removes the part of the small intestine where vitamin B12 is absorbed
- Drugs such as antacids and metformin (used to treat diabetes)
- Repeated exposure to nitrous oxide (laughing gas)
- Atrophic gastritis
- Decreased stomach acidity
- Lack of intrinsic factor.
B12 is often deficient in the elderly, as they often lack either hydrochloric acid or intrinsic factors.
Strict long-term vegetarians (vegans) are at risk of B12 deficiency due to inadequate intake.
Consequences of B12 deficiency
Vitamin B12 deficiency can lead to anaemia. Symptoms may include fatigue, dizziness, palpitations, ringing in the ears. This form of anaemia is more common in the elderly, but other age groups are not immune to it.
In addition, vitamin B12 deficiency can have neurological consequences: tingling in the fingers (paresthesia), memory loss, incoordination, muscle weakness in the legs. Critical B12 deficiency leads to irreversible nerve damage and paralysis.
I discourage you from self-supplementing. If you experience any of the above symptoms, seek medical attention. Based on the results of the tests, your general practitioner will make an accurate diagnosis and prescribe appropriate treatment.
Too much vitamin B12?
There is no tolerable upper limit for vitamin B12 intake established. This means that high doses of this vitamin are not considered toxic/dangerous for health.
Sources of vitamin B12
As mentioned above, vitamin B12 is found almost exclusively in animal products. Algae, mushrooms and fermented soy products contain some B12, but not in active form. It is believed that B12 from plant sources is not absorbed. Good vegetarian sources of B12 are eggs and dairy.
Vegans are recommended whether to take vitamin B12 supplements or consume fortified foods.
An interesting fact: the microwave destroys B12.