What foods rich in vitamin B12 are suitable for a vegetarian diet?

From the Guidelines

Vegetarians should supplement their diets with reliable sources of vitamin B12, such as fortified foods or supplements, to ensure adequate intake. According to a recent overview of pediatric nutrition guidelines and position papers from 2015-2020, published in Clinical Nutrition in 2021 1, vegetarian diets can be adequate but require careful planning to meet nutritional needs, including vitamin B12.

Key Points to Consider

• Vegetarian populations need to investigate the adequacy of their diets and consider recommendations for supplementation with vitamin B12.
• Reliable sources of vitamin B12 for vegetarians include fortified foods and supplements, as natural sources are limited in plant-based diets.
• The importance of vitamin B12 supplementation is highlighted by its crucial role in nervous system function, DNA synthesis, and red blood cell formation, with deficiency leading to serious health issues like anemia and neurological problems.

Recommendations for Vitamin B12 Intake

• The recommended daily amount of vitamin B12 for adults is 2.4 micrograms, which can be achieved through a combination of fortified foods and supplements for those following vegetarian diets.
• Regular blood testing is essential for monitoring B12 levels in vegetarians, especially vegans, to prevent deficiency and related health issues.
• Fortified foods such as nutritional yeast, plant milks (soy, almond, rice), breakfast cereals, and some meat substitutes can contribute to meeting the daily vitamin B12 needs, but supplements may be necessary to ensure adequacy, as suggested by the overview of pediatric nutrition guidelines 1.

From the Research

Vitamin B12 and Vegetarian Diets

• Vitamin B12 is found almost exclusively in animal-based foods, making it a nutrient of potential concern for those following a vegetarian or vegan diet 2.
• Vegetarians are at risk for vitamin B12 deficiency due to suboptimal intake, with deficiency rates ranging from 11-90% among different populations 3.
• Vegans, and anyone who significantly limits intake of animal-based foods, require vitamin B12-fortified foods or supplements to prevent deficiency 2.

Prevalence of Vitamin B12 Deficiency among Vegetarians

• The prevalence of vitamin B12 deficiency among vegetarians varies depending on demographic characteristics, place of residency, age, and type of vegetarian diet 3.
• Higher rates of deficiency are reported among vegans compared with vegetarians, and among individuals who have adhered to a vegetarian diet since birth compared with those who have adopted such a diet later in life 3.
• Pregnant and lactating vegan or vegetarian women should ensure an adequate intake of vitamin B12 to provide for their developing baby 2.

Diagnosis and Management of Vitamin B12 Deficiency

• Screening for vitamin B12 deficiency is not recommended for average-risk adults, but may be warranted in patients with one or more risk factors, such as gastric or small intestine resections, inflammatory bowel disease, or use of certain medications 4.
• Initial laboratory assessment should include a complete blood count and serum vitamin B12 level, with measurement of serum methylmalonic acid used to confirm deficiency in asymptomatic high-risk patients with low-normal levels of vitamin B12 4.
• Oral administration of high-dose vitamin B12 is as effective as intramuscular administration for correcting anemia and neurologic symptoms, and patients older than 50 years and vegans or strict vegetarians should consume foods fortified with vitamin B12 or take vitamin B12 supplements 4, 5.

Vitamin B12 Status in Health and Disease

• Vitamin B12 deficiency can masquerade as a multitude of illnesses, presenting different perspectives from the point of view of the hematologist, neurologist, gastroenterologist, general physician, or dietician 6.
• Diagnostic biomarkers for B12 status include decreased levels of circulating total B12 and transcobalamin-bound B12, and abnormally increased levels of homocysteine and methylmalonic acid, although the exact cut-offs to classify clinical and subclinical deficiency remain debated 5, 6.
• Management depends on B12 supplementation, either via high-dose oral routes or via parenteral administration, and future directions for diagnostics of B12 status and health interventions are being discussed 5, 6.