4 Things Everyone Needs to Know Before Taking Vitamin B12 Supplements

4 Things Everyone Needs to Know Before Taking Vitamin B12 Supplements

The world of supplements is vast, and if you’re like most people, a bit confusing and intimidating to sort through all of the information. With approximately 29,000 supplements on the market today (just in the US) and around 1,000 more added to the mix annually (also just in the US), you’d hardly be to blame. [According to the FDA

Whether you’ve been taking supplements for years “just because” or are asking yourself whether you should be, follow our Supplement Series for an overview of the whats, whys, and whos of individual supplements. (And please read our disclaimer at the end of this post.)

1) What is vitamin B12?

First, let’s answer the question, “What is vitamin B12?”. You may also know it as cobalamin, a water-soluble vitamin - meaning that it dissolves in water. It is one of the thirteen essential vitamins that our bodies require to function properly (and must be consumed in our diets). Some of the responsibilities of B12 include maintaining the health of nerve and blood cells, as well as helping to make DNA. Basically, it’s used in every cell of the human body.

B12 is made by bacteria and is most commonly consumed in the form of animal products, including poultry, beef, fish, milk, eggs, etc. This is because it builds up in animal tissue and is then absorbed in the small intestine (of humans) once they consume the animal tissue. B12 also used to be found in plants due to the production of B12 in the soil (again, from bacteria), but increasing food cleanliness practices has done away with that source. You may have also seen it on food packaging, such as cereals, as foods fortified with B12 have become more common. And lastly, it can be found in the form of a vitamin B12 supplement.

Fun fact, humans do actually produce vitamin B12 in the large intestine. Unfortunately, B12 is absorbed in the small intestine, which comes before the large intestine in the gastrointestinal tract. Read more about how this may have changed in our evolution here.

2) Why is it important?

Now that we’ve answered what vitamin B12 is, let’s talk about why it’s so important. Nerve cells, blood cells, DNA. Pretty important (and necessary) responsibilities, right? So, what happens if the body doesn’t have enough vitamin B12 to carry out these crucial functions? Some common symptoms are feeling tired and weak, which may indicate megaloblastic anemia (having larger than normal red blood cells and fewer of them). Another type of anemia, pernicious anemia, has to do with a lack of intrinsic factor in the stomach to convert B12. In more severe cases, a vitamin B12 deficiency could lead to serious nerve damage as well as neurological problems.

How much do you need? The short answer, it depends. Always consult your healthcare provider before starting any supplement, as they will likely first perform an exam as well as check your blood levels. From there, they will recommend an appropriate amount for you. Factors that need to be considered include age, whether you’re pregnant or breastfeeding, current blood levels, and certain medical conditions.

While it may seem that the human body got it backward in the intestines, it has an impressive ability to store vitamin B12 (mainly in the liver) for years. In fact, if one were to stop their consumption of B12 in all forms, it would take up to 3-5 years to completely run out. (Disclaimer: this is not a recommendation to go cold turkey just because you “can.”)

3) Who should consider a vitamin B12 supplement?

At this point, you might be asking yourself, if vitamin B12 is predominantly found in animal products, only people who don’t consume them should consider a supplement, right?


It’s true that if you’ve recently switched to a vegan or vegetarian diet or even simply reduced the number of animal products that you consume, you may want to consider a vitamin B12 supplement. However, a lack of B12 in the body does not only affect people who follow a vegan or vegetarian diet. Older adults, as well as people who suffer from gastrointestinal disorders, may also be at risk. This is because older adults may not produce enough hydrochloric acid in their stomachs, which is necessary to absorb vitamin B12. Similarly, disorders that affect the gastrointestinal tract, including surgeries, can decrease absorption as well.

But are they safe?

Vitamin B12 supplements are generally considered safe (continue reading for a note on those with impaired kidney function). Because it is water-soluble, B12 is excreted through the urine. Because the human body can take what it needs and get rid of the rest, consuming too much isn’t considered harmful. However, high doses of B12, which may be prescribed to treat a deficiency, may have some side effects. These include headache, nausea and vomiting, diarrhea, weakness or fatigue, and tingling sensation in the hands and feet. (Yes, some of those are also symptoms of vitamin B12 deficiency.)

4) What is the difference between methylcobalamin and cyanocobalamin?

If you’ve ever looked into vitamin B12 supplements to try and figure out which one to take, you may have stumbled across more options than just varying dosages (which your doctor can help you decide how much is appropriate for you). There are four types on the market, including hydroxycobalamin and adenosyl B12, but we’re only focusing on the two most popular, cyanocobalamin and methylcobalamin.

Cyanocobalamin is often found in the shadows of the seemingly preferable version of vitamin B12 supplements, methylcobalamin. While people may overlook cyanocobalamin as an acceptable source of B12 due to its synthetic composition, it is readily converted in the body to an active form, either methylcobalamin or adenosylcobalamin.

On the other hand, while methylcobalamin appears to be less stable and sensitive to light, it is, in fact, an active form of vitamin B12. It may also be better for those with impaired renal function. These patients have a decreased ability to clear the small amount of cyanide released when converting cyanocobalamin into methylcobalamin. And since methylcobalamin is normally responsible for clearing out the cyanide through conversion to cyanocobalamin (stay with me), the inability to do so prevents that necessary conversion from synthetic form to active form.

Generally speaking, either form could be seen as appropriate in otherwise healthy individuals.

Regardless of which type of vitamin B12 supplement you take, it is important to take it separately. If taken as part of a multivitamin, the other vitamins and minerals present in the same pill can often decide that the active B12 should be destroyed.

And as is also often the case, vitamin B12 supplements may interact with other supplements and medications. Consult your healthcare provider before starting any supplements.

Okay, so you’ve spoken to your healthcare provider, done your research, and have decided that you need to increase your vitamin B12. But you still have a nagging doubt in the back of your mind that is preventing you from considering a supplement. You may think that if B12 is found in nature (animal products), you should just increase your consumption naturally, whether it’s more B12 fortified foods or more animal products. This may not be the best approach.

Often, fortified foods, such as cereals, are also considered processed foods, which can come with many not-so-nice ingredients that are difficult to pronounce and most often mean high sugar content, nutritional yeast being an acceptable exception. Furthermore, increasing the consumption of animal products to increase vitamin B12 levels is also less than ideal. This is due to the associated health risks of consuming high amounts of animal products, including but not limited to cancer.

Ultimately, the safest, cheapest, and healthiest source of vitamin B12 is a supplement. If you have decided that a vitamin B12 supplement is the best course of action for you, consider heading over to our vitamin B12 product page

Health/Medical Disclaimer

This blog post does not provide health or medical advice. This blog post is for informational and educational purposes only and is not a substitute for professional health or medical advice. Before taking any actions based upon such information, we encourage you to consult with the appropriate medical and healthcare professionals. We do not provide any kind of health or medical advice. The use or reliance of any information contained on this blog is solely at your own risk. 


https://www.ncbi.nlm.nih.gov/books/NBK216048/#:~:text=The%20Food%20and%20Drug%20Administration,annually%20(Sarubin%2C%202000). https://ods.od.nih.gov/factsheets/VitaminB12-Consumer/ https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/#:~:text=Vitamin%20B12%20Intakes%20and%20Status,-Most%20children%20and&text=As%20a%20result%2C%20vitamin% https://www.healthline.com/nutrition/methylcobalamin-vs-cyanocobalamin https://nutritionfacts.org/video/the-best-type-of-vitamin-b12-cyanocobalamin-or-methylcobalamin/ https://nutritionfacts.org/2011/08/30/3964/ https://www.mayoclinic.org/drugs-supplements-vitamin-b12/art-20363663#:~:text=Safety%20and%20side%20effects,excess%20passes%20through%20your%20urine https://www.pcrm.org/news/health-nutrition/animal-products-linked-cancer https://www.silversolutionusa.com/chewable-b12-methylcobalamin-100-tablets-1000mcg/ https://www.healthline.com/health/megaloblastic-anemia#outlook https://www.msdmanuals.com/home/disorders-of-nutrition/vitamins/vitamin-b12-deficiency#:~:text=(See%20also%20Overview%20of%20Vitamins,to%205%20years%20to%20exhaust. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6413093/#:~:text=Although%20CKD%20patients%20display%20increased,absorption%20in%20the%20proximal%20tubule

31st May 2021 Brandee Nichols, retired Registered Nurse

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