Vitamin B12 in the vegan diet: why is this important?
The exclusivity and uniqueness of B12 is that without this element, the normal activity of the human nervous system is impossible, and the normal process of hematopoiesis is also impossible.For a healthy life of the human body, this vitamin requires only about 6 to 10 micrograms per day( here it should be noted that this dose must necessarily be broken down into several methods, otherwise B12 is not digested).
Functions of vitamin B12
B12 is the only vitamin that can not be obtained in an amount sufficient for the normal functioning of the human body fromFood of non-animal origin, even under the condition of a perfectly balanced fruit and vegetable diet and a sufficient amount of sunlight.
Many species of herbivores are able to receive vitamin B12, produced by bacteria in their own digestive system.B12 is also present in the soil and some plants.These observations have led many vegans to the idea that the lack of B12 is not a significant problem.For a long time it was believed that spirulina, nori, tempe and barley can be a reliable source of vitamin B12 of non-animal origin.Unfortunately, time has shown that all these conclusions are deeply mistaken.
More than 60 years of research have proved that only foods and supplements enriched with vitamin B12 are able to maintain the level of this vitamin, sufficient for a healthy existence.
What is dangerous is the deficiency of vitamin B12
Chronic vitamin B12 deficiency causes anemia and serious impairment of nervous activity.
In adults, typical symptoms of deficiency are: loss of energy, tingling and numbness of the limbs, decreased sensitivity to pain or pressure, blurred vision, gait disturbance, dry mouth, poor memory, confusion( including hallucinations and personality changes).
Among other things, vitamin B12( along with vitamin B6) is involved in maintaining a normal level of homocysteine in the blood.An increase in the level of homocysteine threatens to destroy the blood vessels and increase the risk of cardiovascular diseases.
Important: most vegans consume vitamin B12 enough to avoid chronic shortages.There are two categories at risk: those who practice vegan for more than 4-5 years, while avoiding products enriched with B12, and infants of mothers-vegans.
Sources of vitamin B12 for vegans
A reliable and regular source of vitamin B12 is needed by everyone.Not only vegetarians and vegans, but also meat eaters( especially people over 50) do not always receive it in sufficient quantities. Optimal variant for vegans - products artificially enriched with vitamin B 12, as well as vitamin complexes or one-component vitamins.
Recommendations for the intake of vitamin B12 in different countries will be different.So, in Europe and in Russia, doctors recommend an adult daily dose of at least 3 micrograms, for pregnant and lactating women - 4 mcg.The consumption rates in the US are slightly lower.
Recommended The Committee on Scientific Evaluation of the US University of Medicine's dietary intake standards by the daily dose of vitamin B12 is:
- for adults 2.0-3.0 μg;
- for pregnant women 3,0-4,0 mcg;
- for nursing mothers 3.0-4.0 μg;
- for children, depending on age and sex, 1.0-2.0 μg;
- for infants 0.3-0.5 μg.
In principle, there is nothing complicated in using products enriched with vitamin B12 and vitamin complexes, to regulate their diet according to these recommendations. It is important to remember that vitamin B12 has one feature - it is absorbed by the human body only in certain( and very small) doses of .The Open Letter of the Vegan Society of Great Britain regarding vitamin B12 states the following:
Vitamin B12 is better absorbed in small doses.When taking doses above 5 μg, its digestibility drops to 1-1.5%.So, with a single intake of 1 μg of vitamin B12, the body absorbs 50% - 0.5 μg, and with a single intake of 1000 μg - only 0.05% -5 μg.In addition, the less often the vegan takes vitamin B12, the more it needs.
Regular consumption of foods fortified with vitamin B12 is a good way to solve the problem.Here it is only necessary to keep in mind: the total amount of B12 at one time should be at least 1 microgram, and a day must be at least three such receptions. The availability of enriched products varies from country to country.And different types of fortified foods contain different amounts of vitamin B12.Therefore, it is always necessary to carefully check the information on the content of B12 in a particular product of a particular manufacturer.
Vitamin supplements containing B12 are meaningful only if, at the recommended daily dose, the amount of this vitamin is at least 10 micrograms( if the amount of vitamin B12 in a single dose is more than 5 μg, the level of digestibility is reduced to 1-1.5%).In supplements with weekly intake, B12 should be contained in an amount of about 2000 micrograms.Such recommendations are provided by the Vegan Society of Great Britain.
The above recommendations are suitable for most people with normal metabolism( the average rate of assimilation B12).Those whose metabolism is slowed down, it is recommended to take 2000 micrograms of B12 weekly.In this case, the process of assimilation will be less dependent on the metabolic rate.
Testing for B12
The blood test for vitamin B12, unfortunately, is rather unreliable.Especially in cases when vegans are tested, eating a large number of algae in one form or another.The fact is that algae and some other plants contain a "false" B12, which during analysis gives an incorrect idea of the true level of vitamin content in the blood.
The homocysteine level of is much more reliable in this case.The most reliable and giving the most accurate information is a test for methylmalonic acid( MMA).If the level does not exceed 370 nmol / l in the blood, then we can say with certainty that the body contains enough vitamin B12.
Many doctors still consider a blood test for B12 that gives reliable information, but it is in the case of vegans that this is not the case.
Marina Zimina, medical reviewer
