Vitamin B12 Deficiency Nutrition Counseling

vitamin b12 nutrition

Written by Olivia Farrow, RD, MHSc

Reviewed by Krista Kolodziejzyk, RD, MPH, MBA

In this guide, we explore the key information practitioners need for effective vitamin B12 deficiency nutrition counseling.

Vitamin B12, also known as cobalamin, plays a vital role in our body’s overall health and well-being. This water-soluble nutrient is involved in various essential functions, including energy metabolism, cell function, and neurological activity (1). Understanding the significance of vitamin B12 and its sources can support you in providing effective nutrition counseling to your clients. 

Dietitian Success Center’s membership includes access to comprehensive yet simplified reference guides for supplements, and client handouts on food sources of vitamin B12.  



Understanding Vitamin B12 Utilization in the Body

Before delving into deficiency and counseling strategies, let’s briefly discuss how the body utilizes vitamin B12. 

Enzymes in the mouth and stomach unbind B12 from food proteins, allowing it to be absorbed and utilized (1). In the duodenum, vitamin B12 is freed from these binding proteins and transported throughout the body by intrinsic factor. However, in supplements and fortified foods, B12 does not need to be unbound from food proteins (1).


Food Sources of Vitamin B12

Vitamin B12 is primarily found in animal food sources such as seafood, meat, poultry, eggs, and dairy products (1). Some plant-based foods may also be fortified with vitamin B12. 

B12 in dairy products is three times more bioavailable than B12 in meat, fish and poultry (1) However, the quantity of B12 is still lower in dairy than in most meats and fish. B12 from fortified foods and supplemental B12 has high bioavailability because it is in its free form and does not require separation from protein. However, the exact quantities in fortified foods can vary and plant-based dietary sources alone may not be sufficient to prevent or correct a deficiency (1).



Foods High in Vitamin B12


Animal Sources

Mussels – 18 mcg / 2.5 oz (75g)

Clams – 15 mcg / 2.5 oz (75g)

Mackerel – 13 mcg / 2.5 oz (75g)

Crab (Alaska King) – 9 mcg / 2.5 oz (75g)

Sardines – 7 mcg / 2.5 oz (75g)

Trout – 6 mcg / 2.5 oz (75g)

Salmon – 4 mcg / 2.5 oz (75g)

Tuna (light) – 2 mcg / 2.5 oz (75g)

Beef – 2 mcg / 2.5 oz (75g)

Cheese – 1 mcg / 1.5oz (50g)

Egg – 1 mcg / 1 egg

Poultry (Chicken, Turkey) – 0.5 mcg / 2.5 oz (75g)

Pork – 0.5 mcg / 2.5 oz (75g)

Milk – 0.5 mcg / 1 cup (250mL)

Yogurt – 0.5 mcg / ¾ cup (175mL)


Plant-Based (Fortified) Sources

Fortified non-dairy beverage – 1 mcg / 1 cup (250mL)

Fortified Nutritional Yeast – 4 mcg / 1 Tbsp

Fortified Breakfast Cereal – 1 mcg / 1 cup


Common Food Sources of B12



Access all of DSC’s ready-to-use client-facing handouts as a DSC member, including Common Food Sources of Vitamin B12. Also included in our FREE Nutrition Client Resource Kit.






The Importance of Addressing B12 Deficiency

Vitamin B12 deficiency can result from various factors, including low intake of B12-containing foods, absorption issues, gastrointestinal surgeries, certain medications, and medical conditions (1,4). Risk factors associated with B12 deficiency include following a vegan diet, aging, some medications and specific medical conditions. 


Symptoms of B12 deficiency may not manifest until B12 levels are significantly low, as the body stores a considerable amount of this nutrient (1). Symptoms of B12 deficiency may include


  • Megaloblastic anemia (large red blood cells with abnormal nuclei)
  • Fatigue
  • Paleness
  • Heart palpitations
  • Dementia
  • Weight loss
  • Infertility
  • Numbness and tingling in hands and feet
  • Depression, mania, delirium, psychosis
  • Poor pregnancy and breastfeeding outcomes (neural tube defects, developmental delays, failure to thrive, anemia in offspring)
  • Low red and white blood cell counts or platelets
  • Glossitis of the tongue 
  • Erectile dysfunction or bowel/urinary incontinence


Recommended Daily Intake for B12 

Recommended Dietary Allowance (RDA)

Daily B12 requirements depend on age, sex, and dietary intake (5)




0-6 months

0.4 mcg (AI)

No Data

7-12 months

0.5 mcg (AI)

1-3 years

0.9 mcg

4-8 years

1.2 mcg

9-13 years

1.8 mcg

14-18 years

2.4 mcg

19+ years

2.4 mcg


2.6 mcg


2.8 mcg


Assessing B12 Status

Typically serum B12 levels are used to determine vitamin B12 deficiency (keep in mind normal value ranges may vary slightly depending on the laboratory).  

  • Serum B12 above 300 pg/mL is often interpreted as normal (6)
  • Serum B12 levels between 200 and 300 pg/mL are considered borderline (in which case further enzymatic testing may be helpful for diagnosis)  (6)
    • Enzymatic testing: serum levels of MMA and homocysteine should both be elevated if B12 deficiency is present; utilizing these values can also help distinguish B12 deficiency from folate deficiency (with folate deficiency, MMA will be normal and homocysteine will be elevated)  (6)
  • Levels less than 200 pg/mL are considered deficient (2) 

Once deficiency is confirmed, it is important to address underlying etiology. This may require further testing (e.g. exploring causes of malabsorption, like Crohn’s), review of surgical history (e.g. gastrectomy) or exploration of dietary intake (e.g. limited consumption with a vegan diet) (6).


Recommending B12 Supplements

The choice of supplementation depends on the severity and underlying cause of the deficiency (1,4). For individuals with mild deficiency or low dietary intake, oral supplementation is often sufficient, with doses ranging from 1000-2000 mcg/day being effective (7). Some research suggests that these doses can be as effective as intramuscular injections in improving serum B12 levels (7).

In cases of severe B12 deficiency, intramuscular injections are typically recommended to ensure adequate absorption (1,4). The standard protocol involves 1000 mcg of B12 given intramuscularly once per week for four weeks before decreasing to once per month (6).

B12 supplements come in various forms, including sublingual tablets, oral tablets, lozenges, and even toothpaste (10). Current research indicates that all these forms of oral supplementation offer comparable absorption rates (1,8,9,10).

For optimal vitamin B12 deficiency nutrition counseling, work with your client to understand what type of supplement would best fit their needs and have the best compliance depending on their unique situation. Some of these factors might include:

  • Cost
  • Gastrointestinal side effects
  • Bioavailability
  • Shelf-stability


B12 Oral Supplement Guide






Low Cost (12)


Shelf stable (12)


Well studied for preventing and reversing B12 deficiency (12)

May contribute cyanide to body accumulation, but this hasn’t been substantiated by research (13)


Not appropriate for patients with CKD (14)


Not the bioactive form – potentially not as well absorbed, but there is conflicting evidence on this (12,13)



Doesn’t need to be converted to active form – may be better absorbed, evidence is conflicting (11,13)

Has not been as well studied as other forms (11)


May be difficult to find in supplement form in some countries (13)



Low cost (comparable to cyanocobalamin) (13)


Most commonly found form in B12 supplements (in some countries)


Doesn’t need to be converted to active form – may be better absorbed, evidence is conflicting (11,13)

May be less stable (shorter shelf-life) than cyanocobalamin (11)



Doesn’t need to be converted to active form – may be better absorbed, evidence is conflicting (11,13)


Preferred form for treating genetic B12 malabsorption (11)

Typically used for parenteral B12 injections, may not be adequately stable in oral form (11)



Key Takeaways

  • Vitamin B12 plays a pivotal role in energy metabolism, neurological health, and red blood cell formation, making it a critical nutrient for overall well-being.
  • Vitamin B12 is found in animal-based foods such as fish, poultry, meat, eggs and dairy products. It is also found in fortified foods, supplements, and prescription medication delivered intravenously.
  • B12 deficiency may be caused by low intake, medication interactions or malabsorption. People at highest risk of deficiency include individuals with pernicious anemia, individuals with gastrointestinal disorders or surgery, breast-fed infants of vegan mothers, individuals following a vegan or vegetarian diet, and the elderly.
  • Recommending appropriate supplementation strategies based on deficiency severity and client needs ensures a well-rounded approach to addressing B12 deficiency.


At DSC, we make it easier for dietitians and dietetic students to build expertise in topics including vitamin B12 supplements. Our vitamin and mineral supplement guides, nutrition courses, ready-to-use client handouts, and community can help you feel more confident. 


Dietitian Success Center is THE professional development resource for dietitians and dietetic students. Our mission is to make it easier for dietitians and dietetic students to build expertise. We do this through evidence-based online nutrition courses, community, and ready-to-use client handouts. Plus – we give you the tools to start and grow your dietitian private practice! 


Disclaimer: the information provided in all written materials is for educational purposes only and is not to be used as medical advice or to diagnose or treat a medical disease. It is strictly for informational purposes and is general in nature. Dietitian Success Center Inc. is not responsible and cannot be held liable for any actions or inactions taken related to the information produced. Consult with your local medical provider before implementing any dietary changes. It is hereby understood that the information provided does not replace medical advice provided by your healthcare provider.



  1. National Institutes of Health. “Vitamin B12: Fact Sheet for Health Professionals”, 2022. National Institutes of Health Office of Dietary Supplements. Available from
  2. Canadian Nutrient File. “Canadian nutrient file search engine online.” (2015).
  3. US Department of Agriculture. “FoodData Central.” (2019).
  4. Shipton MJ, Thachil J. Vitamin B12 deficiency – A 21st century perspective . Clin Med (Lond). 2015 Apr;15(2):145-50. doi: 10.7861/clinmedicine.15-2-145. PMID: 25824066; PMCID: PMC4953733.
  5. Institute of Medicine. 2006. Dietary Reference Intakes: The Essential Guide to Nutrient Requirements. Washington, DC: The National Academies Press.
  6. Ankar A, Kumar A. Vitamin B12 Deficiency. [Updated 2022 Oct 22]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from:
  7. Wang H, Li L, Qin LL, Song Y, Vidal-Alaball J, Liu TH. Oral vitamin B12 versus intramuscular vitamin B12 for vitamin B12 deficiency. Cochrane Database Syst Rev. 2018 Mar 15;3(3):CD004655. doi: 10.1002/14651858.CD004655.pub3. PMID: 29543316; PMCID: PMC6494183.
  8. Yazaki Y, Chow G, Mattie M. A single-center, double-blinded, randomized controlled study to evaluate the relative efficacy of sublingual and oral vitamin B-complex administration in reducing total serum homocysteine levels. J Altern Complement Med. 2006 Nov;12(9):881-5. doi: 10.1089/acm.2006.12.881. PMID: 17109579.
  9. Sharabi A, Cohen E, Sulkes J, Garty M. Replacement therapy for vitamin B12 deficiency: comparison between the sublingual and oral route. Br J Clin Pharmacol. 2003 Dec;56(6):635-8. doi: 10.1046/j.1365-2125.2003.01907.x. PMID: 14616423; PMCID: PMC1884303.
  10. Siebert AK, Obeid R, Weder S, Awwad HM, Sputtek A, Geisel J, Keller M. Vitamin B-12-fortified toothpaste improves vitamin status in vegans: a 12-wk randomized placebo-controlled study. Am J Clin Nutr. 2017 Mar;105(3):618-625. doi: 10.3945/ajcn.116.141978. Epub 2017 Jan 4. PMID: 28052884.
  11. Rizzo G, Laganà AS, Rapisarda AM, La Ferrera GM, Buscema M, Rossetti P, Nigro A, Muscia V, Valenti G, Sapia F, Sarpietro G, Zigarelli M, Vitale SG. Vitamin B12 among Vegetarians: Status, Assessment and Supplementation. Nutrients. 2016 Nov 29;8(12):767. doi: 10.3390/nu8120767. PMID: 27916823; PMCID: PMC5188422.
  12. Obeid R, Fedosov SN, Nexo E. Cobalamin coenzyme forms are not likely to be superior to cyano- and hydroxyl-cobalamin in prevention or treatment of cobalamin deficiency. Mol Nutr Food Res. 2015 Jul;59(7):1364-72. doi: 10.1002/mnfr.201500019. Epub 2015 May 12. PMID: 25820384; PMCID: PMC4692085.
  13. Paul C, Brady DM. Comparative Bioavailability and Utilization of Particular Forms of B12 Supplements With Potential to Mitigate B12-related Genetic Polymorphisms. Integr Med (Encinitas). 2017 Feb;16(1):42-49. PMID: 28223907; PMCID: PMC5312744.
  14. Spence JD. B vitamins for NASH: Use methylcobalamin, not cyanocobalamin. J Hepatol. 2023 Jan;78(1):e34-e35. doi: 10.1016/j.jhep.2022.08.019. Epub 2022 Aug 27. PMID: 3603115

Related Articles

Hey, Krista here! I am a fellow Registered Dietitian, dietitian business coach and the founder and CEO of Dietitian Success Center. These...
Watch the Youtube video here! Nutrition labels, and specifically, the Nutrition Facts Table, can help you compare packaged food and...
Watch the YouTube video here! Youtube Transcript: How to Read a Nutrition Label for Kids. Hey there, today we’re jumping...
Watch the Youtube video here! Are you dealing with morning sickness or nausea during pregnancy? Morning sickness is more accurately...
Watch the Youtube video! Ready to build a healthy plate? In this video (click to watch!) and blog, we’ll dive...
Non-scale victories highlight the positive changes in clients’ lives that aren’t reflected by their weight, helping to maintain motivation and...