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At Healthfully, we strive to deliver objective content that is accurate and up-to-date. Our team periodically reviews articles in order to ensure content quality. The sources cited below consist of evidence from peer-reviewed journals, prominent medical organizations, academic associations, and government data.
- "Nutrition Journal"; Nutrition and Cancer: A Review of the Evidence for an Anti-Cancer Diet; Michael S. Donaldson; 2004
- Office of Dietary Supplements: Vitamin B12
- Linus Pauling Institute at Oregon State University; Vitamin B12; Jane Higdon; March 2003
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So many subjective ways could define “best” that it is impossible to say conclusively that methylcobalamin is the best form of vitamin B-12. It’s definitely not the only form that your body needs. According to the Office of Dietary Supplements, methylcobalamin and 5-deoxyadenosylcobalamin are two types of B-12 that are required by the human body. Learning more about B-12 will help you make an educated decision regarding your sources of B-12.
When it comes to vitamins, B-12 is the largest and most complex in terms of chemical structure. It contains a mineral – cobalt – within its molecular structure. This has lead to the use of the term “cobalamin” to describe compounds that have B-12 activity in the human body.
Both methylcobalamin and 5-deoxyadenosylcobalamin work as cofactors, meaning substances that assist the function of enzymes. As a cofactor, methylcobalamin may be important in cancer prevention, while 5-deoxyadenosylcobalamin plays a role in energy production and hemoglobin synthesis. These two types of B-12 occur naturally in your body. Methylcobalamin is found in animal-based foods and in supplement form, but many B-12 supplements contain synthetic B-12 in the form of cyanocobalamin or hydroxocobalamin.
The most common form of B-12 supplement is cyanocobalamin. When you take cyanocobalamin, your body rapidly converts it into methylcobalamin and 5-deoxyadenosylcobalamin. Cyanocobalamin is available in capsule and tablet form. It can also be used as a nasal gel or as an injectable liquid.
There is a dearth of evidence regarding the differences between cyanocobalamin and methylcobalamin, but it appears there may be some differences regarding their cancer-fighting potential. According to “Nutrition Journal,” methylcobalamin slows the growth of tumors, induces tumor cell death and increases survival time in laboratory rats. These results were not seen in rats treated with B-12 in the form of cobalamin. These results are only preliminary. More research on human subjects is needed to confirm these findings.
For those with atrophic gastritis, a condition that results in insufficient stomach acid, there may be an advantage to taking synthetic B-12 rather than attempting to derive all of your B-12 from natural methylcobalamin food sources. According to the Office of Dietary Supplements, the vitamin B-12 that naturally occurs in foods is bound to protein and must be separated from it in order to be absorbed. Synthetic vitamin B-12 is already in free form and does not depend on digestive acids for absorption.
The recommended dietary allowance for B-12 is the same regardless of whether you obtain your B-12 through food sources, such as liver, salmon or fortified breakfast cereals, or supplements, such as methylcobalamin or cyanocobalamin. Those over the age of 14 are advised to consume 2.4 mcg of B-12 per day. Pregnant women need slightly more, at 2.6 mcg per day. Lactating women are advised to consume 2.8 mcg of B-12 daily.
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