Vitamin B12 is an essential nutrient with numerous key roles, such as red blood cell production and nerve signaling. As you get older, your body’s ability to absorb and utilize this important vitamin declines, putting you at greater risk for B12 deficiency and related fatigue, anemia, and neurological problems. As such, it’s essential to understand the importance of vitamin B12, how much you need to get each day, and how you can ensure you’re getting enough.
In this comprehensive guide, we will cover everything you need to know about vitamin B12, including what it is, why it’s important, how much you need, and if you should consider taking a B12 supplement.
Also known as cobalamin, vitamin B12 is a water-soluble vitamin that belongs to the B-vitamin family. It is bound to the protein in food and is the largest and most structurally complicated vitamin we consume [ 1 2 1
2]. In order to be absorbed by the large intestine, B12 must be released from dietary protein by a combination of saliva, stomach acid, and digestive enzymes [
Vitamin B12 plays a critical role in numerous bodily functions, such as the development and function of the central nervous system, red blood cell production, and DNA synthesis [ 1 3
1]. It also plays a role in producing chemicals that affect mood, emotions, sleep, and other brain functions [
The recommended daily intake of vitamin B12 varies depending on age and life stage, ranging from 2.4-2.8 micrograms (mcg) for adults. Specific recommended intakes are as follows [ 1
Adult men and women: 2.4 mcg/day
Pregnancy: 2.6 mcg/day
Lactation: 2.8 mcg/day
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Several factors can influence your B12 status and needs, including your age, dietary choices, certain health conditions, and medications.
As you age, you absorb less B12 from the foods you eat, which puts older adults at greater risk for B12 deficiency. If you follow a strict vegan or vegetarian diet, you may also find it difficult to get enough B12, as there are limited amounts of B12 in plant-based foods. Pregnant and lactating women also need slightly more B12 to maintain adequate levels and meet the increased demands on the body [ 1
Other factors that can inhibit B12 absorption and thus increase your needs include pernicious anemia, digestive disorders (like celiac disease, ulcerative colitis, or Crohn’s), gastrointestinal surgery, and prolonged use of certain medications, including gastric acid reducers and Metformin [ 1
Foods that are high in B12 include:
Animal-based products, including meats (such as beef, pork, and poultry), fish, dairy products, and eggs [ 1
Fortified breakfast cereals
Fortified nutritional yeasts
Fermented foods and certain types of algae and seaweed
Since vitamin B12 is water-soluble and sensitive to heat, how you cook your food can also impact the amount a food provides. Depending on whether you grill, broil, or simmer meat, 40-60% of B vitamins may be lost in cooking juices and up to 40% lost when roasting meat due to long cooking times at high temperatures [ 4
The good news is, consuming the juices that run off during and just after grilling, broiling, or simmering meat can help you retain between 70-90% of B vitamins, including B12. Additionally, steaming or sautéing meat for a short time without water appears to prevent the loss of heat-sensitive B vitamins [ 4
Because the body stores about 1,000-2,000 times as much as the amount typically consumed in a day, B12 deficiency symptoms can take several years to appear [ 1
1]. Prolonged deficiency can lead to serious health complications, including nerve damage, cognitive decline, and cardiovascular issues.
Your B12 status can be assessed with a simple blood test. At Elo, vitamin B12 levels below 400 pg/mL are considered low.
Common signs and symptoms of B12 deficiency include [ 1
Megaloblastic anemia (characterized by large, abnormal red blood cells)
Glossitis of the tongue
In most cases, vitamin B12 deficiency is usually treated with vitamin B12 injections, since they are administered directly into muscles and bypass gastric and intestinal absorption barriers. However, research has shown that high doses of oral vitamin B12 can also be an effective treatment option for treating B12 deficiency [ 1
The bioavailability of oral B12 supplements (meaning, how much you can absorb and utilize) is about 50% higher than B12 obtained from food [ 1
1]. And since over-the-counter oral supplements are affordable and easily accessible, they may be beneficial for those at risk of or with mild B12 deficiency.
If you have significant B12 deficiency or pernicious anemia, your doctor will likely prescribe B12 injections, which are almost fully absorbed since they are administered into the muscle and are quickly absorbed into the blood [ 1
You should consider taking a B12 supplement if [ 1
You are over the age of 50
You have been diagnosed with a B12 deficiency or pernicious anemia
You follow a strict vegan or vegetarian diet or have a limited dietary intake of B12
You have impaired B12 absorption due to gastrointestinal conditions (including atrophic gastritis, celiac, Crohn’s, etc.) or medications (like Metformin or proton-pump inhibitors)
You have had gastric or intestinal surgery that can affect the absorption of B12
When it comes to supplementation of vitamin B12, taking 25-100 mcg daily has been shown to help maintain B12 levels in older adults [ 5 2
5]. For those with B12 deficiency or significantly impaired absorption, oral doses between 1,000-2,000 mcg may also be appropriate for short periods of time (typically one month) but should be monitored to prevent excessive dosing as B12 levels increase [
At Elo, our registered dietitians can take the guesswork out of what supplements you need and how much you should take. Learn more about our personalized supplements
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Vitamin B12 supplementation is considered safe and has no Tolerable Upper Intake Level (UL) due to its low level of toxicity [ 1 1 6
1]. Even when taken at large doses (1,000-2,000 mcg), a B12 overdose is unlikely because the body only absorbs what it needs and will not store excess amounts [
Oral B12 supplements should be taken with water, either with food or on an empty stomach [ 6
B12 supplements are generally safe and well tolerated but, like any supplement, can have potential side effects and interactions with certain medications.
Fatigue or weakness
Nausea and vomiting
Tingling hands and feet
You can find a multitude of B12 supplements on the market, but not all are created equal.
Unlike food, supplement regulation is largely in the hands of manufacturers, and FDA approval for supplements is only required when the product contains a new ingredient. As such, the best B12 supplement is one that has been third-party tested for quality and purity.
Learn more about Elo’s rigorous
If you’re confused about how much vitamin B12 you should take, there’s no need to worry. At Elo Health, we take the guesswork out of the equation by using science to recommend the right nutrition and supplements for you. Additionally, you have access to our Registered Dietitians and Elo Health coaches
Registered Dietitians and Elo Health coachesto help guide you on your nutrition and health journey.
Your body is unique, and so are your nutrition needs.
Here’s how Elo can help you feel your best.
Vitamin B12 is an essential nutrient with crucial roles in the body, including red blood cell production and nerve signaling. As you age, the ability to absorb and utilize B12 declines, increasing the risk of deficiency and related symptoms such as fatigue, anemia, and neurological problems. Certain gastrointestinal conditions and strict vegan or vegetarian diets can also make it difficult to meet your daily needs.
You can increase your intake of B12 by consuming lean meat and poultry, fish, eggs, and dairy products, or by taking a B12 supplement. While B12 supplements are both safe and effective for treating B12 deficiency and maintaining healthy levels as you age, you should look for B12 supplements that have been third-party tested for purity and quality, such as Elo Health’s smart supplements
Disclaimer: The text, images, videos, and other media on this page are provided for informational purposes only and are not intended to treat, diagnose or replace personalized medical care.
Vitamin B12 is an essential nutrient that plays key roles in DNA synthesis, red blood cell production, as well as the development and function of the central nervous system.
The best food sources of vitamin B12 include meat, fish, poultry, eggs, and dairy products. Fortified foods like breakfast cereals and nutritional yeast can also be good sources.
People who are over 50, strict vegans or vegetarians, individuals with gastrointestinal conditions, or who take Metformin or proton pump inhibitors may want to consider taking a B12 supplement.
Office of Dietary Supplements - Vitamin B12. (2022, December 22). Retrieved July 18, 2023, from https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/
Patel, K. (2023). Vitamin B12. Examine. https://examine.com/supplements/vitamin-b12/
Valizadeh, M., & Valizadeh, N. (2011). Obsessive compulsive disorder as early manifestation of B12 deficiency. Indian journal of psychological medicine, 33(2), 203–204. https://doi.org/10.4103/0253-7176.92051
USDA Table of Nutrient Retention Factors, Release 6. (2018). [Dataset]. https://catalog.data.gov/dataset/usda-table-of-nutrient-retention-factors-release-6
VITAMIN B12: Overview, uses, side effects, precautions, interactions, dosing and reviews. (n.d.). Retrieved July 19, 2023, from https://www.webmd.com/vitamins/ai/ingredientmono-926/vitamin-b12
Vitamin B-12. (2021, July 17). Mayo Clinic. Retrieved July 19, 2023, from https://www.mayoclinic.org/drugs-supplements-vitamin-b12/art-20363663