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The Science Behind Vitamin B12: Are You Getting Enough?

The Science Behind Vitamin B12: Are You Getting Enough?


Vitamin B12, also known as cobalamin, is a water-soluble vitamin that is most notably known for its role in energy production. It is considered an essential nutrient (our bodies cannot produce it on its own), which is the root of why many people are deficient. It is often found in foods such as meat, fish, and dairy, but can also be found in fortified food products (1). People who follow very specific dietary patterns, such as those on vegetarian and vegan diets, are most at risk of vitamin B12 deficiency since they limit their consumption of animal products (2). Some of B12’s essential functions include DNA synthesis, red blood cell formation, neurological function, and energy metabolism (3).

In this comprehensive guide, we'll explore the functions of vitamin B12, sources of this essential nutrient, why certain groups of individuals, particularly vegans, may struggle to obtain enough B12, and what you should look for in a vitamin B12 supplement.


Essential Functions of B12

Vitamin B12 is primarily known for its role in energy production – this is the process of converting food into energy that the body can use.  B12 participates in the breakdown of both fatty acids and amino acids into forms that can be used by our cells to produce energy (4).

Vitamin B12 aids in the creation of new DNA, where B12 helps convert folate to its active form, a necessary step to produce new cells (5). Vitamin B12 is also essential for the formation of red blood cells and the synthesis of hemoglobin, the protein responsible for transporting oxygen throughout the body (6).

In terms of neurological function, vitamin B12 plays a crucial role in the maintenance of the myelin sheath, a protective covering that surrounds nerve fibers and is important for nerve impulses (7).

During pregnancy, vitamin B12 is an important nutrient for the proper growth and development of the baby’s brain and nervous system as well as for proper neural tube formation (8). Maintaining sufficient levels is also important for the overall health and well-being of the mother to prevent fatigue, weakness, and other symptoms of deficiency.


Where to get B12

The primary dietary sources of vitamin B12 are animal-derived foods, including meat, poultry, fish, eggs, and dairy products. These foods contain naturally occurring forms of vitamin B12 that are readily absorbed by the body. The highest concentration of vitamin B12 can be found in organ meats and shellfish.

For individuals following vegetarian or vegan diets, obtaining adequate vitamin B12 can be challenging, as plant foods do not contain significant amounts of this nutrient. In such cases, fortified foods and supplements are essential for meeting vitamin B12 requirements. Fortified foods, such as plant-based milk, breakfast cereals, meat substitutes, and nutritional yeast, can provide reliable sources of vitamin B12 for those with dietary restrictions (9). In addition, supplementing with an all-in-one complete vegan multivitamin such as the plant-based essentials is a good source of vitamin B12 for vegans.


Recommended Daily Intake

The recommended daily intake of vitamin B12 varies by age, gender, and life stage. For adults, the recommended dietary allowance (RDA) is approximately 2.4 micrograms (mcg) per day (10). Pregnant and breastfeeding women have slightly higher requirements, with RDAs of 2.6 and 2.8 mcg per day, respectively (10).

Most supplements contain more than the daily recommended dose because the body does not absorb B12 well, meaning that not all vitamin B12 is absorbed when it is consumed. Some studies suggest that the body absorbs just 2% of a 500 mcg dose (11), which is why it’s important to take more than the RDA. It’s also important to note that the risks of taking too much vitamin B12 are low since B12 is water soluble and any excess gets excreted through the urine (12). In general, people tend to tolerate vitamin B12 well with minimal side effects.


Signs of Deficiency

The body stores vitamin B12 in the liver, so deficiency typically takes several years to develop in individuals with adequate stores (3). However, meeting the recommended intake levels is crucial for preventing deficiency-related health issues. Some experts suggest that higher doses of vitamin B12 may be beneficial for certain populations, such as older adults, individuals with dietary restrictions such as vegans, and individuals with gastrointestinal disorders that impair absorption (13).

Vitamin B12 deficiency can manifest in various ways, ranging from mild to severe symptoms. Common signs and symptoms include fatigue, weakness, shortness of breath, tingling or numbness in the hands and feet, memory problems, and mood changes. If left untreated, vitamin B12 deficiency can lead to more severe complications such as megaloblastic anemia, neuropathy, and cognitive impairment (14). It can also lead to complications during pregnancy if the mother is deficient. Identifying and addressing deficiency early is essential to prevent long-term health consequences.


Why Certain Groups Struggle with Maintaining B12 Levels

Certain populations may struggle with maintaining adequate vitamin B12 levels and include:

Vegans and Vegetarians

Vegans are at a higher risk of vitamin B12 deficiency due to the absence of animal products in their diet (17). Although actual percentages may differ based on age and demographic, one study found that 60% of participants following a vegetarian diet were deficient in vitamin B12 (18).

Unlike some other nutrients, vitamin B12 is not reliably found in plant foods, making it challenging for vegans to obtain sufficient amounts through diet alone. The lack of vitamin B12 can have serious health consequences, emphasizing the importance of supplementation with vegan vitamin B12 or consumption of fortified foods. Vegans should be proactive in monitoring their vitamin B12 status and seek guidance from healthcare professionals to ensure adequate intake.

The plant-based essentials is a vegan multivitamin supplement that has adequate vitamin B12 in its most bioavailable form. This complete vegan multivitamin is specifically designed to treat the most common nutrient deficiencies seen on vegan and plant-based diets, such as vitamin B12 deficiency, and can be purchased here.


Older Adults

Older adults are known to be more susceptible to a vitamin B12 deficiency because their ability to absorb B12 from food decreases (15). This is because of a decrease in stomach acid as we age – stomach acid is essential to access the B12 we get from our diet.


Those with Gastrointestinal Disorders

Certain gastrointestinal disorders such as celiac disease, Crohn’s disease, and inflammatory bowel disease, can damage the lining of the stomach or small intestine, which can cause vitamin B12 malabsorption (16). People with these conditions may benefit from intramuscular B12 injections, which bypass the digestive tract for absorption (3).


Best B12 Supplements

In most cases, people tend to rely on oral B12 supplements to increase their intake. When choosing a vitamin B12 supplement, several factors should be considered, including the form of vitamin B12, dosage, third party testing, and other ingredients in the supplement. Cyanocobalamin and methylcobalamin are the two most common forms of vitamin B12 supplements available on the market. Cyanocobalamin is a synthetic form of B12 and is stable and cost-effective, making it a popular choice (19). However, many prefer methylcobalamin, which is the biologically active form of vitamin B12, meaning it is readily available for the body to use without requiring any conversion to another form (20). This suggests that methylcobalamin, the form of B12 used in the plant-based essentials, likely has higher bioavailability compared to cyanocobalamin, allowing for more efficient absorption of vitamin B12.

Additionally, sublingual or intramuscular formulations of vitamin B12 are available for people who may have difficulty absorbing oral supplements due to gastrointestinal issues (21). Intramuscular B12 injections (B12 shots) have become more common in recent years and are the quickest way to correct a severe deficiency.


How to Incorporate B12 in the Diet

Incorporating vitamin B12-rich foods into the diet is essential for maintaining optimal B12 levels. Main food sources of B12 are animal products, but fortified foods, such as plant-based milk, breakfast cereals, meat substitutes, and nutritional yeast, can be valuable sources of vitamin B12 for those who follow a restrictive diet, such as vegans (17). For individuals who may have difficulty meeting their vitamin B12 needs through diet alone, supplementation is a convenient and reliable option. According to the Mayo Clinic, vitamin B12 supplements are generally safe and well-tolerated, even at high doses, as excess vitamin B12 is excreted in the urine.

B12 levels should be monitored often via blood test, especially in individuals who suspect they may be low in vitamin B12, including vegans, older adults, and those with gastrointestinal issues.



Vitamin B12 is a vital nutrient that plays a critical role in various functions, including energy production, DNA synthesis, red blood cell formation, and neurological function. Meeting the recommended daily intake of vitamin B12 is essential for preventing deficiency-related health issues. While obtaining sufficient vitamin B12 can be challenging for individuals following vegetarian or vegan diets, fortified foods and supplements offer practical solutions. By understanding the importance of vitamin B12 and incorporating it into your diet effectively, you can support your overall health and well-being.



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