B12 might just be one of the strangest and most complex vitamins - and here's why:

1. Only bacteria can synthesize B12.
   Including those that live in our intestines. The problem is, B12 is absorbed in the small intestine, while the bacteria that produce it live in the large intestine (which is lower). So we have to eat B12 with food of animal origin.
2. The B12 molecule is very complex.
   It took 11 years to synthesize it, with more than 100 scientists from different countries working on the project. By the way, this is the only molecule in the human body that contains cobalt.
3. We only need 2 micrograms of B12 a day.
   At the same time, we can store up to 10 times more B12 than we need, providing us with vitamin reserves for several years. This means that vitamin deficiency is quite difficult to achieve if your diet is well-balanced.

Why do we need B12?

Vitamin B12 is involved in the synthesis of red blood cells, nucleic acids and myelin, which accelerates the conduction of nerve impulses along nerve fibers.

What are some sources of B12?

Since vitamin B12 is well stored in animal bodies, it is abundant in meat, fish and seafood. Other sources include animal products — eggs, milk, and all of its products (cheese, butter, yogurt).

If you are a vegetarian, you can find vitamin B12 in tempeh, nori, and Thai fish sauce. You can also turn to vitamin-rich flakes and Chlorella extract.

Symptoms of B12 deficiency:

• Chronic fatigue (even when you wake up)
• Numbness in the hands or feet
• Loss of appetite and weight loss
• Difficulty maintaining balance
• Memory impairment
• Depression
• Irritability 

A B12 deficiency can occur if you do not consume enough of the vitamin in your diet or if you have an absorption issue.

Thus, the risk groups are:

1. Vegetarians and vegans.

Vegans are more likely to suffer from a deficit than vegetarians. The more strictly a person adheres to the nutrition system, the likelier they are to experience a B12 deficiency.

2. People who can't produce Castle factors.

3. People who:

• have undergone resection of the stomach;
• have chronic gastritis;
• chronically take antacids, antibiotics, H2-antihistamines or proton pump inhibitors;
• suffer from alcohol addiction.

4. Elderly people

Among the elderly, B12 deficiency occurs in 10-15% of the population.

What should a person do if they are in an at-risk group?

Consume more products with B12. If you are in the group who can’t produce Castle factors - think about taking vitamin supplements.

A healthy person who eats a balanced diet doesn't need to take additional B12 supplements.