Can Humans Get B12 From Soil? The Dangers of a Nutritional Myth

October 30, 2025 •

4 min read

Vitamin B12 is exclusively produced by microorganisms, such as certain bacteria found in soil. However, despite this fascinating biological fact, the idea that humans can get B12 from soil directly by consuming it or eating unwashed vegetables is a dangerous and incorrect nutritional myth. Modern sanitation practices and agricultural methods have made this an unreliable and unsafe source of a crucial nutrient.

Quick Summary

This article explores the myth of getting vitamin B12 from soil. It uncovers the severe health risks of consuming dirt, from pathogens to heavy metal poisoning, and details why modern agricultural practices have removed this as a viable option. Reliable alternatives, including supplements and fortified foods, are presented.

Key Points

Bacteria Produce B12, Not Humans or Plants: Vitamin B12 is synthesized by microorganisms, including bacteria in the soil, which are then consumed by animals.
Consuming Soil is a Dangerous Health Risk: Eating soil directly, a practice known as geophagia, exposes humans to harmful pathogens like E. coli, parasites, and toxic heavy metals.
Modern Practices Nullify Soil as a B12 Source: Due to sanitation and intensive farming, produce no longer carries enough soil-based B12, and soil health has degraded significantly.
B12 Analogues are Misleading: Some plant-based foods, like spirulina, contain inactive B12 analogues that interfere with the absorption of true, usable B12.
Rely on Safe and Reliable Modern Sources: The safest and most consistent sources of B12 are animal products, fortified foods (like cereals and plant milks), and nutritional supplements.
B12 Deficiency is a Serious Concern: Inadequate B12 intake can lead to severe neurological damage, nerve problems, and megaloblastic anemia.

The Critical Role of Vitamin B12 in Human Health

Vitamin B12, also known as cobalamin, is an essential water-soluble vitamin that plays a pivotal role in numerous bodily functions. It is vital for the health of your nerve cells, helps in the production of DNA and RNA, and is critical for the formation of healthy red blood cells. A deficiency can lead to a type of anemia called megaloblastic anemia, which causes fatigue and weakness, but it can also result in more severe neurological problems, including nerve damage, confusion, and memory loss. Given its critical importance, understanding its sources is key to maintaining good health.

The Bacterial Origin and the Modern Disconnect

Unlike most vitamins, which plants can produce or acquire from the soil in a bioavailable form, vitamin B12 is produced solely by bacteria. These microorganisms are abundant in soil and water environments. In a less hygienic past, some B12 may have been incidentally ingested by early humans through consumption of water from natural sources or from produce that was not thoroughly washed. This is also how grazing animals, like cattle, acquire the B12 that their gut bacteria produce, which is then passed into their tissues, milk, and eggs.

However, modern life has fundamentally changed this dynamic. Today, we rely on sanitation for food safety, which means produce is thoroughly washed and sanitized to prevent exposure to harmful pathogens. Additionally, intensive farming practices have degraded soil health and, in many cases, introduced pesticides and other chemicals that interfere with the natural microbial ecosystems. The B12-producing bacteria are often no longer present in sufficient, safe quantities on modern produce.

The Dangerous Risks of Consuming Soil for B12

The practice of eating dirt or clay is known as geophagia or pica, an eating disorder involving the compulsive consumption of non-food items. Attempting to get B12 this way is not only ineffective but also extremely dangerous for several key reasons:

Exposure to pathogens and parasites: Soil is home to countless microorganisms, including harmful bacteria like E. coli and tetanus, as well as parasites like roundworms. Ingesting soil is a direct route for these pathogens to enter your body and cause serious illness.
Contamination with heavy metals and toxins: Soil can be contaminated with toxic heavy metals such as lead, arsenic, and mercury. These can accumulate in the body and lead to poisoning, causing severe and irreversible health problems.
Nutrient malabsorption: Ironically, consuming soil can actually lead to more nutrient deficiencies. The binding properties of clay in the stomach and intestines can interfere with the absorption of other vital nutrients, including iron and zinc, exacerbating nutritional problems.
Intestinal blockages: Regularly eating soil or clay can lead to constipation and, in severe cases, dangerous intestinal blockages that require medical intervention.

Safe and Reliable Sources of Vitamin B12

Instead of relying on the a historical and dangerous method, modern nutrition offers several reliable and safe ways to ensure adequate B12 intake. The best source depends on your dietary choices.

Comparing B12 Sources


Source	Production Method	Reliability	Key Advantages	Disadvantages & Risks
Soil Consumption (Geophagia)	Bacteria, but modern soil is compromised.	Very Low (Dangerous)	Historically plausible, but not practical today.	High risk of pathogens, toxins, parasites; nutrient malabsorption.
Animal Products (Meat, Dairy)	Bacteria consumed by animal, accumulates in tissues.	High	Naturally present and bioavailable for omnivores.	Not suitable for vegan diets; ethical and environmental considerations.
Fortified Foods (Cereals, Plant Milks)	Lab-produced bacteria cultures added to food.	High	Widely available and convenient for vegans and vegetarians.	Requires consistent consumption; need to check labels for fortification.
Nutritional Yeast	Produced from yeast cultures.	High	Vegan-friendly, often fortified with B12.	Distinct flavor; must be fortified to be a reliable source.
Supplements (Pills, Injections)	Lab-produced bacteria cultures.	Very High	Direct and efficient delivery, high bioavailability.	Requires conscious effort to take regularly; potential for high doses depending on form.

Options for Different Diets

Omnivores: Can get B12 from animal products such as meat, fish, eggs, and dairy. However, even non-vegans can experience B12 deficiency due to absorption issues, especially as they age.
Vegans and Vegetarians: B12 is not naturally present in plant foods in a bioavailable form, so supplementation or consuming fortified foods is essential. Good options include:
- Nutritional Yeast: This deactivated yeast has a cheesy, nutty flavor and is often fortified with a reliable dose of B12.
- Fortified Breakfast Cereals: Many cereals are fortified and can provide a good daily dose.
- Fortified Plant-Based Milks: Soy, almond, and other plant-based milks are commonly fortified with B12.
All Individuals: Supplements are a direct and effective way to meet B12 needs, especially for those over 50 or with absorption issues. B12 supplements are available in various forms, including oral tablets, sublinguals, and injections for those with severe deficiencies.

The Problem with B12 Analogues

It is important to note that not all presumed 'natural' plant-based sources of B12 are reliable. For example, some algae like spirulina contain B12 analogues, or 'inactive' B12, which the human body cannot properly use. Worse, these analogues can compete with the absorption of true B12, potentially worsening a deficiency. Therefore, relying on these sources is not recommended.

Conclusion

The idea that humans can safely acquire vitamin B12 from soil is a dangerous misconception rooted in a time before modern hygiene and industrial farming. While the nutrient originates from bacteria in soil, relying on this method poses significant risks from pathogens, heavy metals, and nutrient deficiencies. For guaranteed safety and efficacy, individuals should choose reliable modern sources. Fortified foods, nutritional yeast, and targeted supplements provide a safe and consistent supply of vitamin B12, ensuring its crucial role in maintaining neurological and overall health is properly fulfilled. Always prioritize proven nutritional strategies over unsupported folk remedies or myths for a healthier diet. For further information on safe B12 sources, consult resources from organizations like the National Institutes of Health.

Frequently Asked Questions

No, it is not safe or reliable to get vitamin B12 from unwashed organic vegetables. While soil bacteria do produce B12, modern agricultural practices and hygiene make this an insufficient source. It also poses a significant risk of ingesting dangerous pathogens like E. coli and parasites.

Consuming soil is dangerous due to the risk of ingesting harmful bacteria and parasites that live in dirt. Furthermore, soil can be contaminated with toxic heavy metals such as lead and arsenic, which can cause severe health problems. Eating clay can also prevent your body from absorbing other vital nutrients.

Some plant-based foods, such as certain algae (like dried nori) and shiitake mushrooms, contain some B12, but the amounts can be unreliable and insufficient to meet daily needs. Many plant-based sources like spirulina contain B12 analogues that are not bioavailable to humans and can actually hinder absorption.

Vegans and vegetarians should get B12 from fortified foods and/or supplements. Reliable fortified options include nutritional yeast, some breakfast cereals, and plant-based milks. B12 supplements are a very reliable and recommended way to ensure adequate intake.

The craving to eat dirt (geophagia) can be linked to nutritional deficiencies, particularly iron and zinc, as well as stress, mental health conditions, and cultural practices. It is a form of pica and should be addressed by a healthcare professional, as eating dirt does not solve the underlying deficiency.

A vitamin B12 deficiency can lead to a range of physical and neurological problems. These include fatigue, weakness, numbness or tingling in the hands and feet, memory problems, confusion, and megaloblastic anemia.

In conventional factory farming, animals are often raised indoors and have no contact with soil. Because of this, artificial vitamin B12 is frequently added to their concentrated feed to ensure they are not deficient.