Which vitamin is not obtained from vegetables?

November 23, 2025 •

4 min read

While vegetables offer a bounty of essential nutrients, providing vitamins A, C, and K, along with important minerals like folate and iron, there is one critical vitamin notably absent from virtually all plant-based sources. The vitamin that is not obtained from vegetables is Vitamin B12, or cobalamin, making it a key nutritional consideration for vegans and vegetarians.

Quick Summary

Vitamin B12 is not naturally found in vegetables; it occurs almost exclusively in animal products. This crucial nutrient is essential for nerve function and red blood cell formation, and those on plant-based diets must get it from fortified foods or supplements.

Key Points

Vitamin B12 is Absent from Vegetables: The only vitamin that is not naturally present in vegetables is Vitamin B12, or cobalamin, as plants do not require it for their metabolism.
Animal Products are Natural Sources: Naturally-occurring Vitamin B12 is found almost exclusively in foods of animal origin, including meat, fish, eggs, and dairy products.
Fortified Foods Offer Vegan B12: For vegans, fortified foods like certain breakfast cereals, plant-based milks, and nutritional yeast are essential dietary sources of B12.
Supplements are a Reliable Option: Due to the inconsistent B12 content in some fortified products, supplements are a highly reliable and recommended source for vegans and vegetarians to ensure adequate intake.
Deficiency Causes Serious Health Issues: A lack of B12 can lead to serious health problems, including megaloblastic anemia, fatigue, nerve damage, and neurological symptoms.
Older Adults and Others Are Also at Risk: Beyond diet, age, certain medications (like metformin), and digestive disorders can impair B12 absorption, requiring supplementation even for some omnivores.
Proactive Planning Prevents Deficiency: Understanding and planning for B12 intake, especially for those on plant-based diets, is crucial for preventing deficiency and maintaining long-term health.

The Vitamin Absent from Plant Sources

The vitamin that is not obtained from vegetables is vitamin B12. Unlike most other vitamins which can be synthesized by plants, B12 is produced by bacteria and primarily accumulates in the tissues of animals that consume these bacteria. For this reason, a diet based solely on vegetables, fruits, and grains will inherently lack this vital nutrient unless it is fortified or supplemented.

Why B12 Isn't in Vegetables

The reason vegetables don't contain natural B12 is a fundamental biological distinction. Plants do not require vitamin B12 for their metabolic processes, and thus, they have not evolved to produce or store it. In contrast, B12 is an essential cofactor for enzyme function in humans, playing a critical role in nerve tissue health, brain function, and red blood cell production. Ruminant animals, for instance, have bacteria in their digestive tracts that produce B12, which the animal then absorbs. Humans rely on external sources, and for much of history, these sources were exclusively animal-based.

The Importance of Vitamin B12

Vitamin B12, also known as cobalamin, is a water-soluble vitamin that plays a number of crucial roles in the body. Its functions are diverse and critical for overall health:

Red Blood Cell Formation: It is essential for the synthesis of DNA, a process vital for producing healthy red blood cells. A deficiency can lead to a condition called megaloblastic anemia, which causes fatigue and weakness.
Nervous System Function: B12 is necessary for maintaining the health of nerve cells, including the myelin sheath that insulates them. Severe deficiency can lead to neurological problems such as tingling, numbness, and even permanent nerve damage.
Brain Health: It helps support normal brain function. Psychological symptoms like confusion, memory loss, and mood changes can occur with prolonged deficiency.

Sourcing B12 Beyond Vegetables

For those on a plant-based diet, obtaining sufficient vitamin B12 requires intentional dietary planning. Relying on chance is not a viable strategy. The primary options are animal products for omnivores and fortified foods or supplements for vegans.

Comparison: B12 Sources


Source Type	Examples	B12 Content	Considerations
Animal Products	Meat (beef liver, salmon, tuna), eggs, dairy (milk, yogurt), shellfish (clams)	Often naturally very high. Clams and beef liver are exceptionally rich.	Highest natural bioavailability, but not an option for vegans.
Fortified Foods	Breakfast cereals, nutritional yeast, plant-based milks (soy, oat), some meat substitutes	Added by manufacturers. B12 levels can vary; checking labels is crucial.	Accessible option for vegans, but requires consistent consumption of fortified products.
Supplements	Oral tablets, B12 injections, nasal gels	Available in various dosages, often much higher than daily needs for better absorption.	Reliable and convenient for those with dietary restrictions or absorption issues. Absorption is higher than from food.

Why Fortified Foods and Supplements are Important for Vegans

Because vitamin B12 is not naturally present in fruits or vegetables, vegans and some vegetarians are at a higher risk of deficiency. Fortified foods help bridge this nutritional gap by adding the bacteria-derived B12 during processing. However, even with regular consumption of fortified products, relying on them as a sole source can be risky due to inconsistent intake and varying levels. For this reason, many health authorities and nutritionists recommend a reliable B12 supplement as a cornerstone of a healthy vegan diet.

Symptoms and Risks of B12 Deficiency

A vitamin B12 deficiency can go unnoticed for years, as the body can store large amounts in the liver. When stores are depleted, symptoms can emerge and worsen over time. Initial signs might be subtle, such as unexplained fatigue or weakness, but they can progress to more serious neurological and psychological issues.

Common physical symptoms:

Feeling very tired or weak
Sore, red tongue with potential ulcers
Pale skin

Common neurological symptoms:

Tingling or numbness in the hands and feet (pins and needles)
Difficulty walking and balancing
Memory loss and confusion

These symptoms highlight why a reliable source of B12 is non-negotiable for anyone avoiding animal products. A simple blood test can reveal low B12 levels, and treatment typically involves supplements or injections to restore levels.

Conclusion: Strategic Dietary Planning is Key

For those whose diet includes animal products, obtaining sufficient vitamin B12 is typically not an issue. However, anyone following a vegan or strict vegetarian lifestyle must recognize that the crucial vitamin B12 is not obtained from vegetables naturally. It is imperative to seek out alternative sources. Fortunately, with the wide availability of fortified foods and high-quality dietary supplements, it is entirely possible to meet daily B12 requirements and maintain optimal health on a plant-based diet. Proactive and strategic dietary planning, including regular supplementation, is the best approach to prevent deficiency and its potential health consequences. Learn more about B12 from reliable sources like the NIH.

Frequently Asked Questions

Vegetables do not contain Vitamin B12 because plants do not need it for their metabolic processes. This vitamin is produced by bacteria and primarily found in animal products, as animals absorb it from these bacteria or consume other animals that do.

The best non-vegetable sources of Vitamin B12 include meat, fish, poultry, eggs, and dairy products. Some of the richest sources are clams, beef liver, salmon, and fortified foods like cereals and nutritional yeast.

It is extremely difficult for a vegan to get enough Vitamin B12 from diet alone without consuming fortified foods. Since plant-based foods do not contain natural B12, regular and consistent intake of fortified products or a supplement is necessary.

Initial signs of a Vitamin B12 deficiency can be subtle, often including fatigue, weakness, or feeling tired easily. Other early symptoms might involve a sore tongue, headaches, or palpitations.

Fortified foods can be a good source of B12, but the amount can vary. The bioavailability of B12 from supplements is generally higher than from food sources. Animal products contain naturally occurring B12, which is highly bioavailable for most people.

The body stores a large amount of B12 in the liver, so it can take several years for a deficiency to manifest symptoms after eliminating animal products from the diet. This delay is why regular testing and supplementation for at-risk individuals is critical.

Individuals following a strict vegan or vegetarian diet are at high risk. Other risk groups include older adults (who may have reduced absorption), people with digestive disorders like Crohn's disease or celiac disease, and those who have had stomach surgery.

Some fermented foods like tempeh and certain seaweeds may contain minimal amounts of B12, but this is highly inconsistent and unreliable. They are not considered dependable sources for meeting daily B12 needs, especially when compared to fortified foods or supplements.