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.




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). These symptoms can range from megaloblastic anemia to neurological and psychiatric disturbances (e.g. Vision loss, memory loss, dizziness, etc.) (1,4). Recognizing these signs is crucial in early detection and intervention.


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 (6). Some research suggests that these doses can be as effective as intramuscular injections in improving serum B12 levels (6).

Intramuscular injections are typically recommended in cases of severe B12 deficiency 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 (5).

B12 supplements come in various forms, including sublingual tablets, oral tablets, lozenges, and even toothpaste (9). Current research indicates that all these forms of oral supplementation offer comparable absorption rates (1,7,8,9).

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

The DSC Vitamin B12 Evidence Summary provides you with a comprehensive comparison chart of the different forms of vitamin B12 supplements available based on the factors listed above.  

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! 


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. Ankar A, Kumar A. Vitamin B12 Deficiency. [Updated 2022 Oct 22]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from:
6. 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.
7. 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.
8. 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.
9. 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.

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