Vitamin B12: The Ultimate Guide to Understanding its Importance and Sources

Vitamin B12: The Ultimate Guide to Understanding its Importance and Sources

Vitamin B12 is a crucial nutrient in maintaining a healthy body and mind (1). This vitamin is vital for overall well-being, from boosting energy levels and supporting the nervous system to promoting healthy skin and hair.

However, despite its importance, many people need to know what vitamin B12 is and where to find it. This ultimate guide will explore everything you need to know about vitamin B12, including its functions (1), recommended daily intake (5), deficiency symptoms (3), and sources (4).

We'll also address common misconceptions surrounding vitamin B12, such as whether one can obtain it from plant-based foods. So, whether you're a health enthusiast or simply curious about the benefits of this essential nutrient, read on for the ultimate guide to vitamin B12.

Why is Vitamin B12 important?

Vitamin B12 is a water-soluble vitamin which is essential for a wide range of the body's functions. One of vitamin B12's primary roles is producing red blood cells. It's also essential for a properly functioning nervous system, as it makes myelin, the protective sheath surrounding nerve cells.

In addition, vitamin B12 is vital for DNA synthesis and cell division, which is essential for growth and repair of the body's tissues (1). Vitamin B12 is also essential for maintaining the immune system, as it helps you produce the white blood cells that fight off infection (2). 

It also plays a critical role in the metabolism of fats and carbohydrates, which is vital for energy production. Finally, vitamin B12 is critical in maintaining healthy skin and hair and supporting cognitive function and mood (1).

Vitamin B12 deficiency and its symptoms

Vitamin B12 deficiency is a common problem, particularly among older adults and vegetarians or vegans who do not consume animal-based foods. Symptoms of B12 deficiency include weakness, fatigue, lightheadedness, pale skin, and a sore tongue. Other symptoms may include constipation, diarrhea, loss of appetite, and weight loss.

In more severe cases, vitamin B12 deficiency can lead to neurological problems, including numbness and/or tingling of hands and feet, difficulty walking, and memory loss. These symptoms may be irreversible if left untreated, so it's important to recognize the vitamin B12 deficiency signs and seek treatment as soon as possible (3).

Sources of Vitamin B12 - Animal-based and plant-based

Vitamin B12 is found naturally in animal-based foods, including meat, fish, eggs, and dairy products. For this reason, vegetarians and vegans have an especially high risk of a vitamin B12 deficiency.

However, some plant-based foods are fortified with the cyanocobalamin form of vitamin B12, including cereals, soy products, and nutritional yeast. It's important to note that the vitamin B12 found in plant-based foods is not the same as the vitamin B12 found in animal-based foods.

The vitamin B12 in plant-based foods is typically in the form of analogs, which the body does not absorb well (if at all). For this reason, vegetarians and vegans need to consume a daily vitamin B12 supplement to ensure they are getting enough of this critical nutrient (4).

Recommended daily intake of Vitamin B12

The recommended vitamin B12 intake varies depending on age and gender. For adults, the daily recommendation is 2.4 micrograms per day (5). Pregnant women should aim for 2.6 micrograms per day while breastfeeding women should aim for 2.8 micrograms per day (8).

It's important to note that a higher daily intake of vitamin B12 is recommended for people over 50, as absorption of this vitamin decreases with age (5). B12 from food and from supplements also have different interactions in the body, so supplements will be many times more concentrated (there is no upper limit of B12 and excess is simply excreted in urine).

Vitamin B12 supplements - Types and Dosage

Vitamin B12 supplements come in several forms, including tablets, capsules, and sublingual drops. It's essential to choose a supplement that suits your needs based on age, gender, and dietary restrictions. It is also necessary you choose one that contains one of the active forms of vitamin B12, which is methylcobalamin or adenosylcobalamin.

The recommended dosage of vitamin B12 supplements depends on the form of the supplement and individual needs. For most people, daily consumption of 1000 micrograms is sufficient to maintain adequate levels of vitamin B12. However, higher doses may be necessary for people with severe deficiency or malabsorption problems.

The reason for this is less than 1% of the amount consumed in supplement form is typically absorbed (meaning you'd need to consume one 100x more concentrated than the daily recommendation as a minumum) and any excess is excreted in the urine. Therefore, following the dosage instructions on the supplement label or a healthcare professional's direction is essential (6).

You can find our favorite B12 supplement here

Vitamin B12 injections - Benefits and Risks

Healthcare professionals may sometimes recommend B12 injections to treat severe deficiency or malabsorption problems. Unfortunately, it's a common misconception that injections are better absorbed than supplements: it has been shown that they're equally well-absorbed, but you should always stick to the advice of your healthcare provider.

Vitamin B12 injections are administered intramuscularly, typically in the arm or thigh. The benefits of vitamin B12 injections include rapid absorption and the ability to bypass the digestive system, which may be beneficial for people with digestive problems.

However, there are also risks associated with vitamin B12 injections, including pain, redness, and swelling at the injection site. More severe reactions can occur (in rare cases), including an allergic reaction or nerve damage. For this reason, vitamin B12 injections should only be administered by a healthcare professional and only when necessary (7).

Vitamin B12 and pregnancy

Vitamin B12 is vital for pregnancy, as it is essential for proper fetal development. Pregnant women deficient in vitamin B12 may be at risk of complications such as preterm birth, low birth weight, or neural tube defects. For this reason, pregnant women should ensure they're getting enough vitamin B12 in their diet or through supplementation (8).

Vitamin B12 and aging

As we age, our ability to absorb dietary vitamin B12 decreases which can lead to a higher risk of vitamin B12 deficiency, particularly among older adults. In addition, some medications commonly used by older adults, such as proton pump inhibitors and metformin, can also affect vitamin B12 absorption (9).

For this reason, older adults need to ensure they are getting enough vitamin B12 in either diet or through supplementation. Regular monitoring of vitamin B12 levels may also be recommended for older adults, particularly those with digestive problems or other health issues that may affect absorption (9).

Conclusion: How to ensure adequate Vitamin B12 intake

Vitamin B12 is a crucial nutrient in maintaining a healthy body and mind (1). It is important to include animal-based foods in your diet, particularly meat, fish, eggs, and dairy products, to ensure adequate intake of vitamin B12. For vegetarians and vegans, it is essential to take a vitamin B12 supplement or eat fortified foods to ensure proper consumption (4).

It is also essential you watch for the signs of vitamin B12 deficiency and to seek treatment if necessary (3). In addition, regular monitoring of vitamin B12 levels might be recommended for people at risk of deficiency, such as older adults or people with digestive problems (9).

In conclusion, vitamin B12 is an essential nutrient that should not be overlooked. By understanding the importance of this vitamin and taking steps to ensure adequate intake, you can maintain optimal health and well-being throughout your life (1).

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Why is Vitamin  B12 Important


(1) Functions of Vitamin B12, Including Its Role in Red Blood Cell Production and Nervous System Support: Green, R., & Allen, L. H. (2011). Vitamin B12 deficiency. Nature reviews Disease primers, 1, 15040. doi:10.1038/nrdp.2015.40

(2) Vitamin B12 and Its Role in the Immune System: Tamura, J., Kubota, K., Murakami, H., Sawamura, M., Matsushima, T., Tamura, T., ... & Naruse, T. (1999). Immunomodulation by vitamin B12: augmentation of CD8+ T lymphocytes and natural killer (NK) cell activity in vitamin B12-deficient patients by methyl-B12 treatment. Clinical & Experimental Immunology, 116(1), 28.

(3) Symptoms and Effects of Vitamin B12 Deficiency: Stabler, S. P. (2013). Vitamin B12 deficiency. New England Journal of Medicine, 368(2), 149-160.

(4) Sources of Vitamin B12: Watanabe, F., Yabuta, Y., Bito, T., & Teng, F. (2014). Vitamin B12-containing plant food sources for vegetarians. Nutrients, 6(5), 1861-1873.

(5) Recommended Daily Intake of Vitamin B12: Allen, L. H. (2009). How common is vitamin B-12 deficiency?. The American journal of clinical nutrition, 89(2), 693S-696S.

(6) Types and Dosages of Vitamin B12 Supplements: Antony, A. C. (2003). Vegetarianism and vitamin B-12 (cobalamin) deficiency. The American journal of clinical nutrition, 78(1), 3-6.

(7) Vitamin B12 Injections: Benefits and Risks: Butler, C. C., Vidal-Alaball, J., Cannings-John, R., McCaddon, A., Hood, K., Papaioannou, A., ... & Dunstan, F. (2006). Oral vitamin B12 versus intramuscular vitamin B12 for vitamin B12 deficiency. Cochrane Database of Systematic Reviews, (3).

(8) Vitamin B12 and Pregnancy: Sukumar, N., Rafnsson, S. B., Kandala, N. B., Bhopal, R., Yajnik, C. S., & Saravanan, P. (2016). Maternal tissue stores of vitamin B12 may meet demands of lactation. American journal of clinical nutrition, 103(1), 172-185. 

(9) Vitamin B12 and Aging: Wolters, M., Ströhle, A., & Hahn, A.


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