If you are considering transitioning to a plant-based diet or have done so already, you have probably come across some conflicting information regarding vitamin B12. Some sources claim that a vegan diet is dangerous because of the risk of vitamin B12 deficiency. On the other hand, many people are able to live and thrive on a vegan diet while supplementing B12, while still others live vegan and claim to be healthy with no supplements at all.
At some point you will find yourself wondering, “Should I take vitamin B12?”
All these conflicting opinions may make it hard to decide what the best course of action is for you, but the answers are out there. The first step is to understand what vitamin B12 is, what it does in the body, and what scientific research has found regarding the risks of vitamin B12 deficiency. Then, you can evaluate the different options for obtaining vitamin B12 and decide what action you can take to keep your B12 levels in a healthy range.
What is vitamin B12?
Vitamin B12 is a water-soluble vitamin that has many functions in the body. It is the most chemically complex of all the vitamins and exists in several forms, which are collectively known as cobalamins. They are given this name because all forms of B12 contain the element cobalt. Vitamin B12 is synthesized through a complex process either aerobically by bacteria or anaerobically by archaea, a group of ancient single-celled organisms (1). These microorganisms live and produce vitamin B12 in the intestines of animals, in the soil, and in water.
What vitamin B12 does for your body.
Vitamin B12 is essential for multiple processes in the human body. First, it is needed for proper red blood cell formation. Severe vitamin B12 deficiency can cause pernicious anemia, in which there is a shortage of red blood cells, or megaloblastic anemia, in which red blood cells are abnormally large. Either type of anemia causes fatigue, weakness, and tingling and numbness in the extremities (3).
Vitamin B12 also helps neurological function through the synthesis of myelin, the protective coating around nerve cells. B12 deficiency may cause neurological symptoms such as depression, poor memory, and difficulty concentrating. If left untreated for too long, the neurological damage from B12 deficiency can become irreversible (2). Vitamin B12 is also needed for cell growth and division throughout the body, DNA and RNA synthesis, and metabolism of macronutrients (4). Studies have found that excessive levels of vitamin B12 are not associated with any adverse side effects (2).
Sources of vitamin B12.
As mentioned earlier, vitamin B12 is synthesized by microorganisms in the intestines and the natural environment. However, B12 presents a problem for vegans because it is naturally only found in significant amounts in animal products (2). B12 is present in animal products because those animals consume it in soil while grazing, are given supplements, or possibly obtain it directly from their intestinal bacteria.
In nature, plants do not uptake sufficient amounts of B12 to account for human dietary needs. However, a recent study showed that the B12 content of water cress can be improved by increasing the amount of the vitamin in the growth medium (5). This discovery has not yet been applied outside the laboratory, though, so it doesn’t have any practical use at this point in time (unless you want to try growing your own).
Vitamin B12 is also taken up and stored by certain types of seaweed and mushrooms, and is present in some fermented foods such as tempeh and kimchi. However, getting sufficient vitamin B12 from these sources alone is probably impractical for most vegans.
Options for vegans.
Obtaining vitamin B12 as a vegan takes some effort, but there are several options. Some B12 can be obtained from the few plant foods that naturally contain it. You can also increase your intake by consuming vitamin B12-fortified foods such as nutritional yeast, plant-based milks, or certain cereals.
But the easiest way to ensure you are reliably consuming enough B12 is by taking a dietary supplement. The B12 in supplements is made using fermentation by bacteria, so no animals are harmed in the process. Some supplements may contain gelatin, which is derived from animals, but many vegan options are available.
Vitamin B12 has a very small recommended daily allowance (RDA) compared to other vitamins, but it is still vitally important to consume sources of B12 regularly. The RDA ranges from 0.4 mcg for infants to 2.8 mcg for lactating women. For adults, the RDA is 2.4 mcg (2).
B12 supplements are available as pills, as sublingual tablets, or in liquid form. Sublingual and liquid forms are often marketed as being more readily absorbed by the body, but these claims have not been verified by research. Supplements usually contain the form of B12 called cyanocobalamin, which the body converts to the two forms of B12 that can be metabolized. Vitamin B12 pills or tablets range in dosage from 50 mcg, which should be taken daily, to 5000 mcg, which should be taken weekly. The dosage in the weekly tablets is proportionately large because greater amounts of B12 are absorbed less efficiently. Personally, I like to take a weekly dose of B12 every Sunday so I don’t have to worry about it for the rest of the week. If you’re interested, you can get a supply of your own 5,000 mcg vegan vitamin B12 or try some liquid vitamin B12 on Amazon.
Should I take vitamin B12? If you are vegan, the answer is yes.
I have come to a clear conclusion from researching this topic, and it is shared by the majority of healthcare professionals. If you are eating a plant- based diet, you almost certainly should take vitamin B12 supplements. Eating the odd B12-containing plant for an extra boost is fine, but plant-based foods cannot be relied on for daily needs, especially as part of a typical Western diet.
Vitamin B12 has been a topic of great contention between those who wish to discredit the vegan diet and those who will defend it at any cost. As always, it is important to pay attention to the scientific literature and used it to make informed decisions. In this case, we can see that a vegan diet has many benefits, but B12 deficiency can potentially negate them all. I’m sure you do not want to gamble with the delicate balance of your body’s systems, so order a B12 supplement today and protect your health over the long term.
1. Fang, H., Kang, J., & Zhang, D. (2017). Microbial production of vitamin B12: A review and future perspectives [Abstract]. Microbial Cell Factories, 16(15). doi:10.1186/s12934-017-0631-y
2. Office of Dietary Supplements – Vitamin B12. (2018, March 2). Retrieved August 12, 2018, from https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/?print=1
3. Office of Dietary Supplements – Vitamin B12. (2018, March 2). Retrieved August 12, 2018, from https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/?print=1
4. Kim S, Thiessen PA, Bolton EE, Chen J, Fu G, Gindulyte A, Han L, He J, He S, Shoemaker BA, Wang J, Yu B, Zhang J, Bryant SH. PubChem Substance and Compound databases. Nucleic Acids Res. 2016 Jan 4; 44(D1):D1202-13. Epub 2015 Sep 22 [PubMed PMID: 26400175] doi: 10.1093/nar/gkv951.
5. Office of Dietary Supplements – Vitamin B12. (2018, March 2). Retrieved August 12, 2018, from https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/?print=1