Vitamin B12 also called cobalamin, is a water-soluble vitamin that belongs to the B-group and participates in the metabolism of virtually every cell, affecting mainly the DNA synthesis and regulation.
The main problem with vitamin B12 is its difficult absorption in the body. By deficiency of vitamin B12 is present mainly in vegetarians and vegans, as plant forms are almost impossible to be assimilated.
The bioactive forms of cobalamin, which alone are involved directly in the metabolic and enzymatic reactions, are methylcobalamin and adenosylcobalamin, also known as dibenocozide.
Methylcobalamin is the form that exists in nature. Methylcobalamin is ready to be absorbed by the body. It is the only form of vitamin B12, which can be directly involved in the metabolism of homocysteine.
It regulates homocysteine and maintains heart health. Methylcobalamin does not contain toxic cyanide and it has improved absorption (adenosylcobalamin is a good source of B12, too).
Top 5 Best Selling Vitamin B12 Supplements
Product | Name | Buy on iHerb | Buy on Amazon |
|---|---|---|---|
| #1 Doctor's Best Best Fully Active B12 | ||
| #2 Jarrow Formulas Methyl B-12 | ||
| #3 Solgar Sublingual Methylcobalamin | ||
| #4 Natrol Vitamin B-12 | ||
| #5 Garden of Life B-12 Organic Spray |
What Is Vitamin B12?
Vitamin B12 also called cobalamin, is a water-soluble vitamin that belongs to the B-group and participates in the metabolism of virtually every cell, affecting mainly the DNA synthesis and regulation.
Cobalamin has a complex structure and is the most complex vitamin from the whole B complex. It cannot be synthesized in fungi, plants, and animals, and only bacteria and archaea (single-celled organisms) have the enzymes required for its synthesis.
The best sources of vitamin B12 among foods are animal foods due to bacterial symbiosis. The main problem with vitamin B12 is its difficult absorption in the body. By deficiency of vitamin B12 is present mainly in vegetarians and vegans, as plant forms are almost impossible to be assimilated.
Individuals, who consume meat, are also not protected from that vitamin deficiency because vitamin B12 is absorbed completely into the small intestine and a substantial part of it is lost with consumption. The problem with the shortage of B12 is not recent.
An earlier study from 1982 showed that the serum levels of vitamin B12 are subnormal in 92% of vegans, 64% of lactose-vegans (consuming dairy products) and 47% for Lacto-Ovo-vegans (consuming milk and egg products). The deficit is observed in people consuming meat.
Another study in 2000 found no link between eating meat and vitamin B12 but found massive low levels of vitamin B12 among 3,000 surveyed people. It has concluded that 20 percent of the US population (60 million people) might suffer such a deficiency.
The need for taking extra B12 can be caused by both the deficit, due to increased needs of the body, and its weak absorption in the digestive tract, it is not only regarding food but also food supplements where the oral intake demonstrates low bioavailability.
In this respect, there are differences between the different forms. The peculiarities of the vitamin, its sources, and its difficult assimilability pose challenges in taking it as a dietary supplement and is extremely important for one to choose a digestible and working vitamin B12.
Here one should take into account the different forms and routes of administration. One option is the injectable form that goes around the digestive tract and falls directly into the bloodstream, but the use of injections worries and is burdensome, to say the least, for a large percentage of the users. The second option is oral, easy and casual.
Side Effects of Taking Vitamin B12
What we most often take as vitamin B12 is cyanocobalamin. This form is found in almost all complex formulas and most standalone products with the vitamin. Unfortunately, it is entirely synthetic, and not found in nature, and is used widely because of its low cost and easy manufacturing.
When getting into the body cyanocobalamin has to become methylcobalamin, and toxic cyanide is released in the process. Although a toxic substance, its amounts are negligibly small and therefore they should not be counted as a pronounced side effect.
There are coenzyme forms of vitamin B12. These are bioactive vitamins, which alone are involved directly in the metabolic and enzymatic reactions. These are methylcobalamin and adenosylcobalamin, also known as dibenocozide.
The advantage of the coenzyme forms is their participation in processes where the synthetic cyanocobalamin shows no activity, which is ostentatious for their specific meaning. Cyanocobalamin is not found in natural sources.
Methylcobalamin is the form that exists in nature. Methylcobalamin is ready to be absorbed by the body. The problems with cyanocobalamin occur even in its metabolism, which makes it difficult to be digestible.
To be used by the body, cyanocobalamin must go through a process, which will remove the cyanide molecule, as for this process the antioxidant glutathione is needed.
The drawbacks of removing the cyanide molecule can result in unnecessary use of this valuable antioxidant and dependence of the vitamin metabolism from any glutathione deficit.
Scientists have also established a connection between the metabolism of B12 in its coenzyme forms and the presence of alpha-tocopherol in the body (vitamin E), which makes the reactions depend on its presence.
These statements are not clear and more studies are needed on the effects of alpha-tocopherol on the synthesis of methylcobalamin and adenosylcobalamin.
The basic cobalamin molecule, acquired from food, as well as the one acquired from the conversion of cyanocobalamin, can be processed by all cells to its coenzyme forms - methylcobalamin and adenosylcobalamin.
Both coenzyme B12 forms, in fact, are concentrated in different parts of the body- adenosylcobalamin dominates the cellular tissue, while methylcobalamin is dominant in the blood plasma and other body fluids.
Both coenzymes play different roles in the metabolic processes, which gives them different coenzyme functions. Methylcobalamin and adenosylcobalamin demonstrate better absorption when administered orally, compared to cyanocobalamin.
Although the absorption in the intestinal tract is similar, the coenzyme forms are retained longer in the tissues, the subsequent synthesis of cobalamin in the liver is increased, and the levels of the disposed of cobalamin through the urinary tract are lower.
Benefits of Coenzyme B12
- Improved absorption;
- Longer retention in the tissues;
- Does not contain toxic cyanide;
- Uses less metabolic energy;
- Maintains the synthesis of SAMe (a unique coenzyme function of methylcobalamin);
- Maintains the enzyme methylmalonyl-coenzyme A (a unique coenzyme function of adenosylcobalamin).
Proven and Known Beneficial Properties of Methylcobalamin
- The only form of vitamin B12, which can be directly involved in the metabolism of homocysteine. It regulates homocysteine and maintains heart health. Study on the effect of methylcobalamin on the homocysteine levels has demonstrated a decrease in homocysteine from 14.7 to 10.2 nmol/ml, with the intake of 1000 micrograms per day for the period of three weeks;
- It enhances the synthesis of SAMe (S-adenosylmethionine), the most important methyl donor in the body by converting homocysteine into methionine. As a result, it enhances neurotoxicity protection;
- A neurotrophic effect and enhancement of the growth of the nerve cells, which helps restore the central and peripheral nerve tissues damaged by amyotrophic sclerosis and diabetic peripheral neuropathy;
- A brain protector against damage from glutamate. It protects the retinal neurons from damage caused by glutamate neurotoxicity, dependent on the N-methyl-D-aspartate receptor. Cyanocobalamin does not demonstrate results under the same conditions;
- It improves the sleep in deviations. Researchers have suggested that this may be due to the effects of methylcobalamin on the secretion of melatonin. Others associate it with its effects on the circadian rhythm. In clinical studies methylcobalamin shows positive effects in the treatment of patients with hypersomnia syndromes and abnormal sleep-wake schedule;
- It is successfully used in patients with vitamin B12 deficiency;
- Increases the levels of leukocytes in the blood and is one of the most powerful immunomodulators;
- Proven benefits in children with autism; it has a positive effect on 90% of the treated children;
- Positive results for the treatment of certain forms of anemia. Demonstrates better results than adenosylcobalamin and cyanocobalamin;
- It is alleged that it shows positive results in the treatment of HIV and tumors. Scientists link the function of the coenzyme forms of the prevention and treatment of cancer. Both coenzyme forms demonstrate an increase in the survival of mice suffering from leukemia. Cyanocobalamin shows no activity. The results are positive, but more research is needed;
- It demonstrates increased sperm production by 37-39%. Does not affect hormones;
Proven and Known Beneficial Properties of Adenosylcobalamin
- Positive results in the treatment of certain forms of anemia. Shows weaker results than methylcobalamin and better than cyanocobalamin. Successfully used by pregnant women in combination with folic acid;
- Positively treats anorexia nervosa. It is used in combination with carnitine. Besides improving the body condition, there is also increased capacity for intellectual activities;
- Potential for the prevention and slowing of the development of cancer;
- It helps in the prevention of testicular atrophy, which is characterized by decreased levels of zinc, magnesium, and potassium in testicles. Methylcobalamin does not show similar results;
- Adenosylcobalamin in combination with P-5-P demonstrates positive effects in the treatment of infectious, allergic myocarditis. The combination shows antiarrhythmic and cardiotonic effects.
How Much Vitamin B12 Should I Take
The therapeutic dose of methylcobalamin varies between 1000 and 6000 mcg. There are no differences when using higher doses. It is possible daily doses of 100 mcg a day to show positive effects, but with a long-term intake.
The effective doses of adenosylcobalamin are the same. Both coenzyme forms during clinical studies have been taken orally, intravenously and intramuscularly. There are no noted differences in the results.
The oral forms of vitamin B12, like tablets and capsules, have a decreased assimilation. A better choice is to use dragees for sucking. This is an effective way to increase the levels of B12 by using the mucosa for transportation.
Both coenzyme forms demonstrate high tolerance and a lack of toxicity. Their complete safety, when taken by pregnant women, has been clinically established. There are no established side effects in any of the studies. There might be individual isolated cases.
In conclusion, we can summarize that science gives an unconditional answer about the effectiveness of coenzyme B12, given that they are subject to numerous and diverse research.
Methylcobalamin and adenosylcobalamin show complete superiority regarding synthetic B12 not only in absorption but also in increased activity and properties that are not typical for any synthetic form.
