Is B12 Deficiency Common in Vegetarians?

November 26, 2025 •

3 min read

According to numerous studies, vitamin B12 deficiency is common among vegetarians, with some reviews indicating a prevalence as high as 86% in certain groups, such as children. The central reason for this is that vitamin B12 is produced by microorganisms and is not reliably present in unfortified plant-based foods.

Quick Summary

Yes, B12 deficiency is common in vegetarians due to limited intake from a plant-based diet. This article explores the prevalence, symptoms, and risks of B12 deficiency, while also providing guidance on how vegetarians can ensure adequate intake through fortified foods and supplements.

Key Points

High Prevalence: Studies show a high rate of vitamin B12 deficiency among vegetarians, though the risk is greater for vegans.
Limited Food Sources: B12 is not naturally present in unfortified plant-based foods, making dietary intake challenging for those avoiding meat.
Silent Symptoms: Deficiency symptoms like fatigue and memory issues can be subtle and mistaken for other conditions, delaying diagnosis.
Reliable Sources: The most dependable ways for vegetarians to get B12 are through fortified foods like cereals and nutritional yeast, and through supplements.
Supplementation is Recommended: Due to variable B12 content in non-meat sources, supplements are the most reliable method to prevent and correct deficiency.
Risk for All Ages: The risk extends across all age groups, including pregnant women and children, highlighting the need for vigilance.

Understanding Vitamin B12 and Dietary Risks

Vitamin B12, or cobalamin, is an essential nutrient crucial for red blood cell formation, DNA synthesis, and neurological function. Since it is exclusively produced by bacteria, animal-based foods are the natural dietary source for humans. This is why vegetarian and, even more so, vegan diets, pose a significant risk of deficiency without careful planning. While ovo-lacto-vegetarians (who eat eggs and dairy) have some B12 sources, the intake from these foods is often insufficient to meet daily requirements, especially as absorption efficiency declines with age. Vegans, who consume no animal products at all, are at the highest risk.

Prevalence of Deficiency in Vegetarians

Research has repeatedly shown a high prevalence of subnormal B12 status in vegetarians and vegans globally. A 2013 review of 18 studies found widespread deficiency across different vegetarian populations, regardless of age, residency, or specific diet type. Some of the reported deficiency rates were alarmingly high in vulnerable populations, such as pregnant women (62%) and children (25–86%). The misconception that deficiency only manifests after many years on a plant-based diet is false; depletion can occur within a couple of years.

Symptoms and Complications of Deficiency

B12 deficiency can cause a range of physical, neurological, and psychological symptoms, many of which can be subtle and easily overlooked in the early stages. Long-term, untreated deficiency can lead to serious and potentially irreversible complications.

Common symptoms include:

Fatigue and weakness
Numbness or tingling in the hands and feet (paresthesia)
A sore, smooth tongue
Memory loss and confusion
Depression, irritability, and other mood changes
Difficulty with balance and walking
Anemia, causing pale or yellowish skin
Increased heart rate and shortness of breath

Dietary Strategies to Prevent Deficiency

Given the high risk, vegetarians and vegans must be proactive in ensuring adequate B12 intake. The most reliable methods are consuming fortified foods and using supplements.

Fortified Foods

Nutritional Yeast: Often fortified with B12, this is a popular choice for its cheesy, nutty flavor. Two tablespoons can meet the daily requirement.
Fortified Plant-Based Milks: Soy, almond, oat, and rice milks are commonly fortified with B12. Checking labels for vitamin content is essential.
Breakfast Cereals: Many cereals are fortified with B12 and can provide a significant portion of the daily value.
Fortified Meat Substitutes and Spreads: Products like vegan burgers and spreads such as Marmite often have B12 added.

Supplements

Oral Supplements: B12 supplements are available in various forms, including tablets, drops, and sprays. The recommended form, cyanocobalamin, is stable and well-researched. Oral supplementation can be as effective as injections for many.
Weekly or Daily Dosing: The optimal dosage can vary, but frequent, smaller doses (e.g., 50-100 mcg daily) or larger weekly doses (e.g., 500-1000 mcg) are common.

Supplementation vs. Fortified Foods


Feature	Fortified Foods	Supplements
Convenience	Integrated into daily meals.	Can be taken easily once daily or weekly.
Bioavailability	Generally high due to being protein-unbound.	Absorption rates depend on dosage; higher doses saturate absorption.
Consistency	Requires consistent daily consumption of multiple fortified products.	A single pill or spray provides a consistent, reliable dose.
Availability	Availability and fortification levels can vary by brand and country.	Widely available in different dosages and forms.
Efficacy	Less effective for correcting existing deficiencies compared to supplements.	Highly effective for both prevention and correction of deficiencies.
Cost	Part of regular grocery spending.	A separate expense, but generally inexpensive.

Conclusion

Is B12 deficiency common in vegetarians? The clear answer is yes, although the risk is lower than for vegans who exclude all animal products. The dietary restrictions inherent in a vegetarian diet, combined with the fact that B12 is not naturally present in plants, create a significant risk for deficiency. The symptoms can be subtle and develop gradually, but the long-term consequences are severe. While consuming dairy and eggs offers some B12, it is often not enough. Therefore, the most prudent approach for all vegetarians, and especially vegans, is to ensure a reliable intake of vitamin B12 through regular consumption of fortified foods and/or supplements. Routine monitoring of B12 status is also highly recommended to enable early intervention and prevent serious health complications.

Learn more about vitamin B12 on the NIH Office of Dietary Supplements fact sheet.

Frequently Asked Questions

Vegetarians are at risk because vitamin B12 is naturally found almost exclusively in animal products. Plant-based foods do not contain active B12 unless they are fortified or contaminated with microbes during cultivation, which is not a reliable source.

While dairy and eggs contain some vitamin B12, the amount is often insufficient to meet daily requirements, and absorption can be less efficient than from other sources. For many vegetarians, especially those who consume very few animal products, supplements or fortified foods are still recommended.

Contrary to the myth that it takes many years, B12 deficiency can develop within the first two years of adopting a plant-predominant diet. The body has some B12 stores, but they can be depleted faster than many assume.

Initial symptoms often include fatigue, lack of energy, pale skin, mood changes, and memory problems. These are non-specific and can be easily overlooked, which makes monitoring B12 status important.

Reliable sources include fortified nutritional yeast, fortified breakfast cereals, fortified plant-based milks (like soy or almond), and certain fortified meat substitutes. It is important to check product labels to confirm fortification.

It depends on your overall dietary intake and lifestyle. While fortified foods are helpful, it can be challenging to consume them consistently in sufficient amounts every day. For guaranteed intake, a regular B12 supplement is the most reliable method.

Yes, studies have shown higher rates of deficiency in vulnerable populations, such as pregnant women, children, and the elderly. Pregnant and breastfeeding women have increased needs, and absorption decreases with age.