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Vitamin B12: Sources, Forms, Benefits, Dosage & Deficiency Symptoms

Your body needs certain levels of micronutrients to keep it healthy and functioning at its best. Some micronutrients, like vitamin B12, are harder to get than others. A lack can cause serious health consequences like difficulty sleeping or memory ...
Vitamin B12: Sources, Forms, Benefits, Dosage & Deficiency Symptoms

Article at a Glance

  • Vitamin B12 is one of the thirteen essential vitamins you need in your diet for heart and brain health.
  • Vitamin B12 is naturally and mostly found in animal products. It is encouraged for vegans, vegetarians, and those following a plant-based diet to use nutrition supplements or fortified foods to obtain adequate levels of this nutrient.
  • Choose supplements that use the active form of vitamin B12, methylcobalamin, for optimal absorption. Check with your healthcare provider about the dosage that works best for you.
  • Vitamin B12 deficiency is one of the more common nutrient deficiencies. If a deficiency is suspected, it is important to receive proper diagnosis and treatment to avoid serious health complications.

Your body needs certain levels of micronutrients to keep it healthy and functioning at its best. Some micronutrients, like vitamin B12, are harder to get than others. A lack can cause serious health consequences like difficulty sleeping or memory loss. Read more below to understand why your body needs vitamin B12, and what you can do for your body to make sure it gets enough of the nutrients it needs.

What Is Vitamin B12?

Vitamin B12 is one of the thirteen essential vitamins needed in your diet because your body cannot make enough on its own.[1] Like all B vitamins, vitamin B12 is water-soluble and dissolves in water. This dissolution allows excess to be easily flushed out of your body instead of being stored in your liver or fat tissue.[1] As your body does not store this vitamin it is uncommon to develop toxic side effects.

Why You Need Vitamin B12

Vitamin B12 is essential for many of your body's physiological functions, such as DNA synthesis, neurological function, and red blood cell development.[1] Other benefits of vitamin B12 include:[1,2,3]

  • Energy — Like most B vitamins, vitamin B12 helps provide and boost your energy levels.
  • Heart — Vitamin B12 is specifically important when it comes to your cardiac health. Without this vitamin (and the help of some others), an amino acid called homocysteine will accumulate in your body and can cause cardiovascular disease.
  • As vitamin B12 lowers homocysteine levels it can also help prevent cardiovascular disease.
  • Brain — Lowered homocysteine levels can also help prevent cognitive decline, including dementia and Alzheimer's.
  • Research shows that inadequate vitamin B12 intake and high levels of homocysteine are linked to Alzheimer's disease.

Where to Get Vitamin B12

Vitamin B12 is mostly found in animal products because of the microorganisms, such as bacteria and fungi, present in their environment or GI tract. [1][4]

Vitamin B12 is only naturally available in limited food sources such as:

  • Clams
  • Dairy products
  • Beef
  • Fish (salmon, trout, tuna)
  • Eggs

You can also get vitamin B12 from fortified foods, such as cereals and nutritional yeast, or nutrition supplements.[2] Fortified or supplemented vitamin B12 is recommended if you do not consume animal products.

Supplemented vitamin B12 through MICROGEL technology is best for optimal absorption. This delivery system allows you to fully absorb nutrients into your bloodstream, and then into cells, where they work to improve health.

The Forms of Vitamin B12

The forms of vitamin B12 you will most commonly see in nutrition supplements are cyanocobalamin and methylcobalamin. These two forms are not equal, and we recommend to do your homework and check the ingredients before picking a nutrition supplement.

  • Cyanocobalamin – The cheap form of vitamin B12 that most nutrition supplements will use. This is the inactive form of vitamin B12 and your body will need to convert it into the active form to be used.[2]
  • Methylcobalamin – An active coenzyme form of vitamin B12 that is preferred for nutrition supplements. For people with the genetic mutation MTHFR, this is the only form their body can use. 
  • Adenosylcobalamin – The other coenzyme form of vitamin B12. This is also a good form for use in nutrition supplements and may support higher energy production in the body. 

How Much Vitamin B12 do You Need?

Everyone is different, and certain factors such as your age, sex, or health will affect your unique nutritional needs differently than others. To provide a general guide, the Food and Nutrition Board (FNB) establish the Recommended Dietary Allowance (RDA) to meet the needs for most healthy individuals. The RDA for vitamin B12 in both men and women range:[2]

  • Infants (0 – 12 months): 0.4 – 0.5 mcg/day
  • Children (1 – 8 years): 0.9 – 1.2 mcg/day
  • Adolescents (9 – 18 years): 1.8 – 2.4 mcg/day
  • Adults (19+ years): 2.4 mcg/day
  • Pregnant and nursing women: 2.6 – 2.8 mcg/day

Specific groups may need to be more mindful when evaluating vitamin needs. If you are pregnant or nursing, be sure to talk with your doctor about receiving adequate levels of nutrients. Inadequate intake of vitamin B12 for these moms and moms-to-be can lead to a risk of neurological issues for the baby.[2]

If you have any other health condition or concern, it's important to talk to your doctor or registered dietitian about your nutrition, especially when choosing which supplements are optimal for your health. Certain health conditions or medications may alter your specific needs.

Can You Overdo it with Vitamin B12?

Generally speaking, vitamin B12 is not toxic because it is water-soluble and excess is easily flushed out of your body rather than stored in your liver or fat tissue.[1] Since it is not stored in these organs, vitamin B12 has no known toxic effects, and a tolerable upper intake level (UL) has not been established.[1] A tolerable upper intake level is the maximum daily consumption level that may cause an adverse event.

Although it is viewed as non-toxic, too much of anything can be harmful at some point. It is always wise to consult with your doctor before introducing any nutritional supplement into your regimen to avoid complications or mega-dosing on any nutrient.

Vitamin B12 Deficiency — Are You at Risk?

Vitamin B12 deficiency is a common nutrient deficiency and can be characterized by these symptoms:[1]

  • Numbness in your extremities
  • Neurological issues
  • Fatigue
  • Difficulty sleeping
  • Memory loss
  • Anemia

It is important to note these symptoms can be caused by a number of factors, and one of the ways to rule out this deficiency is to ask your physician to test your nutrient levels with a blood test. Keep in mind that the symptoms of vitamin B12 and folate deficiency are almost equivalent, and it is imperative to receive the proper medical diagnosis and treatment.[1]

Those at risk include:

  • Older individuals — As we get older our bodies don't digest and absorb nutrients the way they once did years prior.[1] Along with less efficient digestion and absorption, our diets may change and it may also become more difficult to eat foods higher in vitamin B12.[1] If you are over 50, it is suggested to take a supplement or opt for fortified foods to help combat deficiency.
  • Vegans, vegetarians, and infants of pregnant or nursing vegan or vegetarian moms — These groups are notably at risk as vitamin B12 is naturally absent from plant food sources.[2][4] It is advised to take a supplement and eat fortified foods if you choose to follow a plant-based diet.
  • Anemics — Specifically, pernicious anemics are at risk for this nutrient deficiency. With this autoimmune disease, a stomach produced protein called the intrinsic factor is destroyed and hinders vitamin B12 absorption.[1][2]This can result in a deficiency, and vitamin B12 injections may be required for this type of anemia.[2]
  • Those suffering from gastrointestinal disorders — Celiac and Chron's disease may cause malabsorption of vitamin B12 due to inflammation and damage in the GI tract, specifically the small intestine where most nutrients are absorbed.[1][2]
  • Those prescribed certain medications — Take precaution if using Metformin to treat diabetes or proton inhibitor medications such as Prilosec® of Prevacid® to treat gastrointestinal conditions. These medications may stop the body from optimally absorbing Vitamin B12.[2]

Vitamin B12 in Healthycell Products

Bioactive Multi — Best for absorption!
The form of vitamin B12 contained in Bioactive Multi is methylcobalamin and adenosylcobalamin. The dosage of vitamin B12 is 19.2 mcg, which satisfies 800 percent of the Daily Value (%DV).

Healthycell Pro
The form of vitamin B12 contained in Healthycell Pro is methylcobalamin. The dosage of vitamin B12 is 100 mcg in the morning formula and 20 mcg in the evening formula, for a daily dosage of 120 mcg, satisfying 2,000 percent of the Daily Value (%DV).

The form of vitamin B12 contained in Healthycell methylcobalamin. The dosage of vitamin B12 is 120 mcg in the morning formula and 6 mcg in the evening formula, for a daily dosage of 126 mcg, satisfying 100 percent of the Daily Value (%DV).

Conclusions and Recommendations

  • Vitamin B12 needs to be present in your diet because your body cannot make enough of this nutrient on its own for proper cardiac, cognitive, and other physiological functions.
  • Vitamin B12 toxicity is rare, but deficiency is common and includes symptoms of numbness, fatigue, and memory issues.
  • The best form of vitamin B12 for optimal absorption is methylcobalamin delivered through MICROGEL technology.


1. McGuire, Michelle, PhD, and Kathy Beerman A., PhD. "Chapter 10
Water-Soluble Vitamins." Nutritional Sciences: From Fundamentals
to Food. 2nd ed. Australia: Thomson/Wadsworth, 2007. 464-466. Print.

2. "Office of Dietary Supplements – Dietary Supplement Fact Sheet:
Vitamin B12."National Institutes of Health. U.S. Department of Health
and Human Services, n.d. Web. 18 Jan. 2017.

3. Clarke R, Birks J, Nexo E, Ueland PM, Schneede J, Scott J, et al. Low vitamin
B-12 status and risk of cognitive decline in older adults. Am J Clin Nutr 2007;

4. Brasaemle, Dawn, PhD. "Folate Lecture." Rutgers University – Vitamin B12.
New Brunswick. 2015. Lecture

5. Brasaemle, Dawn, PhD. "Folate Lecture." Rutgers University – Folate. New
Brunswick. 2015. Lecture

6. Marcason, Wendy, RDN. "What Are B-Vitamins and Folate?" Ear Right.
Academy ofNutrition and Dietetics, 14 Dec. 2015. Web. 14 Oct. 2016.

About The Author

Katie Vita works at Healthycell as Corporate Trainer and Nutrition Educator. She holds a Bachelor's degree in nutritional science with a concentration in dietetics from Rutgers University. To stay healthy, she eats a vegetarian diet, practices yoga, and meditates daily. Katie is a nutritionist and certified health coach, guiding people to lead healthier, more fulfilling lives.

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