What is vitamin B12 found in?

December 13, 2025 •

3 min read

According to the National Institutes of Health (NIH), vitamin B12 is naturally present in a wide variety of animal foods, but not in plant foods unless fortified. Essential for nerve function and red blood cell formation, finding out what is vitamin B12 found in is a critical step for maintaining good health and preventing deficiencies.

Quick Summary

Vitamin B12 is naturally sourced from animal products such as meat, fish, eggs, and dairy. For those on plant-based diets, sufficient B12 intake relies on consuming fortified foods and supplements. Deficiency can lead to serious neurological and hematological issues.

Key Points

Animal Products: Vitamin B12 is found naturally in animal-based foods like meat, fish, eggs, and dairy.
Top Sources: The richest natural sources of B12 include beef liver, clams, and certain fish like salmon.
Fortified Foods: Vegans and vegetarians must get B12 from fortified foods such as nutritional yeast, cereals, and plant-based milks.
Absorption Issues: Age and certain medical conditions, like atrophic gastritis and pernicious anemia, can impair B12 absorption.
Supplementation: Supplements are a reliable option for individuals with dietary restrictions or absorption problems to meet their B12 needs.
Essential Function: B12 is vital for red blood cell production, nervous system health, and DNA synthesis.

Vitamin B12, also known as cobalamin, is a vital nutrient that plays a crucial role in red blood cell formation, cell metabolism, nerve function, and the production of DNA. Since the human body does not produce it naturally, it must be obtained through diet. The primary natural sources of B12 are animal-based, but a growing number of fortified foods and supplements are available to meet dietary needs, especially for those following vegan or vegetarian lifestyles.

Animal-Based Sources of Vitamin B12

Animal products are the most bioavailable and richest sources of naturally occurring vitamin B12. Consuming a balanced diet that includes these foods typically provides sufficient amounts for most individuals.

Meats and Poultry

Beef: Organ meats like beef liver are exceptionally high in B12, but muscle meat is also a significant source. A 3-ounce serving of beef liver provides many times the daily value.
Poultry: Chicken and turkey contain vitamin B12, with slightly lower amounts than red meat but still contributing to daily intake.

Fish and Shellfish

Clams and Oysters: These shellfish are among the absolute best sources of vitamin B12, containing extremely high concentrations.
Salmon and Tuna: Fatty fish like salmon and canned tuna are excellent sources of B12 and other nutrients like omega-3 fatty acids.
Sardines and Mackerel: These small, oily fish are also packed with vitamin B12.

Dairy and Eggs

Milk: Both dairy milk and products like yogurt and cheese are good sources of vitamin B12.
Eggs: A large egg contains a portion of the daily recommended B12, found primarily in the yolk.

Fortified and Plant-Based Sources

Since vitamin B12 is not naturally found in plants, vegans and strict vegetarians must rely on fortified foods or supplements to meet their needs.

Nutritional Yeast

This deactivated yeast has a cheesy, nutty flavor and is often fortified with B12, making it a popular and reliable source for vegans. It can be sprinkled on popcorn, pasta, and salads.

Fortified Cereals and Grains

Many breakfast cereals and some breads are fortified with vitamin B12. Checking the nutrition label is essential to ensure they contain added B12.

Plant-Based Milks and Meat Alternatives

Soy milk, almond milk, and other plant-based beverages are often fortified with B12 to mimic the nutritional profile of dairy milk. Some meat substitutes, like certain brands of tofu or tempeh, may also be fortified.

Factors Affecting B12 Absorption

Several factors influence how well the body absorbs vitamin B12. As people age, their ability to produce the stomach acid needed to release B12 from food diminishes. Other conditions can also interfere with absorption.

Intrinsic Factor: This protein is produced in the stomach and is essential for absorbing B12 in the small intestine. Pernicious anemia is a condition caused by a lack of intrinsic factor.
Digestive Disorders: Conditions like Crohn's disease, celiac disease, and atrophic gastritis can impair the gut's ability to absorb B12.
Medications: Certain drugs, including some heartburn medications and the diabetes drug metformin, can lower B12 absorption.

Comparison of Top Vitamin B12 Food Sources

To illustrate the difference in B12 content, here is a comparison of common food sources, based on standard serving sizes where appropriate.


Food Source	Serving Size	Approximate B12 (mcg)	Natural/Fortified	Notes
Beef Liver	3 oz, pan-fried	70.7	Natural	Extremely rich source
Clams	3 oz, cooked	17.0	Natural	A potent source, especially for shellfish lovers
Fortified Nutritional Yeast	1/4 cup	8.3–24.0	Fortified	Content can vary by brand
Salmon	3 oz, cooked	2.6	Natural	Excellent source from fatty fish
Beef (Ground)	3 oz, pan-browned	2.4	Natural	Solid source for meat-eaters
Milk (2%)	1 cup	1.3	Natural	A common dairy source
Fortified Cereal	1 serving	0.6+	Fortified	Content varies by brand and type
Egg (Whole)	1 large	0.5	Natural	Yolk contains most of the B12

Conclusion

Vitamin B12 is essential for many bodily functions and is predominantly found in animal products, including meat, fish, eggs, and dairy. For individuals on plant-based diets, consuming fortified foods like nutritional yeast and fortified cereals is necessary. Supplements, available in various forms, also serve as a reliable source, particularly for those with absorption issues or dietary restrictions. Whether through a diverse diet or careful supplementation, ensuring adequate B12 intake is key to maintaining overall health and preventing deficiency. For more information, consult resources such as the NIH Office of Dietary Supplements fact sheet on Vitamin B12.

Frequently Asked Questions

The best source of vitamin B12 depends on your diet, but naturally, the richest sources are animal products. Beef liver and clams are among the most concentrated, while fortified nutritional yeast is a top source for vegans.

No, vitamin B12 is not naturally present in plant foods. Some plant-based products like certain types of seaweed or tempeh may contain trace amounts, but these are not considered reliable sources due to inconsistent content.

Individuals at a higher risk for deficiency include older adults, people with digestive disorders like Crohn's or celiac disease, those who have had stomach surgery, and individuals following a vegan or strict vegetarian diet.

Many older adults produce less stomach acid, which is necessary to separate vitamin B12 from its food protein, a crucial step for absorption. This means they may benefit more from supplements or fortified foods, where the B12 is already in a free form.

Vitamin B12 is generally considered safe, even in larger doses, as it is a water-soluble vitamin and excess amounts are typically excreted. Some minor side effects, such as headache or nausea, might occur in sensitive individuals.

Symptoms can include fatigue, weakness, numbness or tingling in the hands and feet, a sore tongue, memory problems, and even changes in mood. If left untreated, it can lead to more serious neurological issues.

The recommended dietary allowance (RDA) for adults is 2.4 micrograms (mcg) per day. Pregnant and breastfeeding women require slightly more, while those over 50 may need higher amounts due to absorption issues.