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Vitamin B12: The Importance and Benefits to Your Health

By Peter Steele AP, DOM

Vitamin B12 Sign

One of the most recommended and prescribed supplements in the world is vitamin B12. Also known as cobalamin, B12 is a member of the B vitamin family, a group of water-soluble compounds that are essential to cellular metabolism and the formation of red blood cells. Cobalamin is particularly important for the health of a person’s red blood cells; deficiency can lead to anemia over time, causing such symptoms as fatigue, weakness, shortness of breath, dizziness, and cold extremities.

Many people are aware of dietary factors that can cause a deficiency of B12, such as the avoidance of animal products for personal, religious, or health reasons (there are only a few non-animal derived sources of B12, such as certain mushrooms, seaweeds, and fermented foods). These individuals therefore supplement B12 in their diet, either by taking a supplement or consuming vegan sources of B12. However, fewer people are aware of other factors that can contribute to underutilization or deficiency of cobalamin.

Thanks to recent advances in molecular biology, we now have a better understanding than ever before of how different genetic factors can play a role in nutrient metabolism. With cobalamin, there are several SNPs, or single nucleotide polymorphisms, that can affect how the body is able to absorb, transport, transform, or excrete different bioactive compounds. If you think of our genetic code like the 1’s and 0’s of traditional computers, then a SNP is a place in your code where most people have a 0, but you have a 1 instead (or vice-versa). Sometimes these polymorphisms are beneficial, improving health and resilience. Other times, they can have adverse effects.

One important gene where SNPs can interfere with B12 absorption is GIF, or gastric intrinsic factor. Intrinsic factor is a compound that is secreted by the stomach that enables the body to absorb dietary B12. Certain SNPs can reduce the efficacy of GIF and, by extension, the absorption of B12. Individuals with these issues may therefore benefit from B12 injections that would bypass the digestive system.

Another gene called TCN2 codes for a compound called transcobalamin that assists in the transport of vitamin B12 to the tissues. Once again, certain SNPs can seriously impact the ability of transcobalamin to do its job, meaning that B12 is not being delivered to all parts of the body as well as it should. These individuals may benefit from higher doses of B12 that help to “push” this essential vitamin into the tissues through sheer volume.

There are also a series of genes that code for compounds that are essential to a process in the body called the Methionine Cycle that takes B12 and converts it to a bioactive form, then combines it with folate and homocysteine to create an important compound called methionine, an essential amino acid. This means that first, a gene called MTRR is used to produce an enzyme called 5-Methyltetrahydrofolate-Homocysteine Methyltransferase Reductase which transforms cobalamin into its bioactive form. Then, another gene called MTR produces an enzyme called methionine synthase which catalyzes the conversion into methionine. Unsurprisingly, SNPs with these genes can sometimes cause suboptimal outcomes in the body’s ability to produce bioactive B12 and methionine. These patients may benefit from taking the bioactive forms of B12 and folate (called methylcobabalmin and methylfolate) so that MTRR is not necessary. They can also supplement methionine in their diet if there are issues with MTR.

B12 comes in many different forms.

As mentioned previously,they are all structurally similar but with a few key differences that make them more suited to different roles.

One of the most used forms is called cyanocobalamin. This is a synthetic form of B12 that is produced by bacterial fermentation with the addition of potassium cyanide and sodium nitrite. Although this is the cheapest form of B12 available and the most widely prescribed and used in supplements, it also has the highest incidence of side effects and adverse events reported. In addition, for patients with the MTRR issues discussed previously, it will be difficult for their bodies to take cyanocobalamin and methylate it to make the bioactive methylcobalamin. This means that it is not always the best form of B12 for patients to supplement and can explain why some people who need B12 do not experience benefit from taking this specific form.

Of the natural cobalamins, methylcobalamin (or methyl-B12) is probably the best well-known by most people. This is the bioactive form of B12 found in the cytosol (fluid found inside the cell) that can be used by the body in various metabolic processes. Directly supplementing this form of B12 means that you do not have to worry about potential genetic issues with methylation. However, intravenous or subcutaneous B12 injections may be warranted if someone has absorption or transport issues. Injections may also be warranted for people who have a much higher need for B12 than most. One such group of people would be smokers; free cobalamin in the body will readily bind to toxic cyanide (becoming cyanocobalamin) and ferry it out of the body in the urine. Because smokers are constantly exposed to cyanide in cigarette smoke, they will burn through much more B12 than most people.

Hydroxocobalamin is another form of B12 that is used by the body as a storage and transport form. When the body has enough B12 to do what it needs, it can convert it to hydroxocobalamin to use later when there is more demand (in a similar fashion to how power plants will store energy in a battery during off-hours for use during peak demand). This is the usually the form chosen to supplement for individuals who have cyanide toxicity as it readily loses its hydroxo ligand to pick up free cyanide.

Adenosylcobalamin is the final form of B12, and probably the least well-known. This is because it is a form of B12 that is used exclusively by mitochondria, the small bacteria-like organelles inside of our cells that perform several vital tasks. One of these is to use adenosylcobalamin to make L-methyl-malonyl-CoA mutase, an important part of the cycle by which mitochondria produce energy for our cells to use. Supplementing this form of cobalamin can be particularly helpful when the goal is to improve cellular energy and metabolism. With all these various factors at play, it can often be hard for individuals to figure out on their own what kind of B12 to take, how much they might need, or even the best dosing method. By working together with a healthcare professional to navigate these intricacies, people can make sure that they are getting what they need, at the level that they need, in the way that they need.

Key Takeaways

  • There are many factors that influence an individual’s need for and ability to use certain vitamins
  • Some of these factors involve an individual’s genetic SNPs (“snips”), slight variations in their genetic code from that of most people
  • Many vitamins come in different forms but are often sold or labeled as the same thing when they may in fact behave very differently
  • B12, or cobalamin, is one such vitamin
  • Due to genetic SNPs, some people are not able to absorb, transport, or produce enough B12
  • In addition, there are different forms of vitamin B12 that have different strengths and weaknesses

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