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Vitamin B12, otherwise known as cobalamin, is a water-soluble vitamin that plays a critical role in red blood cells production, DNA synthesis, nerve and neurological function, energy metabolism, and many other biological processes.

Animal products, including meat, seafood, eggs, and dairy, are easily the most valuable sources of vitamin B12, but that is not to say that the vitamin is produced by animals. Let us explain further.

Vitamin B12 is produced by bacteria lodged in the soil. When animals graze, they take up B12-producing bacteria attached to the roots of plants. The bacteria then produce vitamin B12 in the lumen to be transported in the blood and stored in the muscles.

Vegans don’t eat animal-based products, neither do they eat dirt or soil attached to freshly harvested fruits or veggies. So how do they get vitamin B12 in their diet? Are all vegans doomed to be B12 deficient?

Vitamin B12 deficiency in vegetarians/vegans is a conversation that causes confusion or fear in the hearts of people wanting to switch to a plant-based diet and even persons who embraced veganism without researching factual information.

Causes of Vitamin B-12 Deficiency

Aside from low intake of foods rich in B12, digestive problems like celiac disease, atrophic gastritis (inflammation of the stomach lining), and Crohn’s disease may negatively impact B12 absorption and ultimately lead to a deficiency. Other causes of vitamin B12 deficiency include:

• Surgery in the GI tract
• Lack of intrinsic factor (e.g., because of pernicious anemia)
• Prolonged use of certain medications (e.g., metformin and gastric acid inhibitors)

Signs and Symptoms of Vitamin B12 Deficiency

Early vitamin B12 deficiency symptoms include:

• Low appetite
• Poor memory and cognitive difficulties
• Weakness and poor fatigue
• Amenorrhea (absence of menstruation)
• Neuropathy resulting in numbness and tingling sensations in the hands and feet
• Nausea
• Slow or troubled digestion
• Pale and jaundiced skin

And if proper measures are not taken to raise B12 levels, the symptoms may worsen and result in any of the following:

• Permanent nerve damage
• Megaloblastic anemia
• Mouth ulcers or glossitis (inflammation or soreness of the tongue)
• Blurred vision or complete blindness
• Reduced mobility
• Deafness
• Pregnancy complications
• Neural tube defects in newborns and developmental delays in children
• Brain damage or increased risk of neurodegenerative diseases
• Hallucinations, confusion, and psychiatric problems

To test for vitamin B12 deficiency, ask your doctor for a methylmalonic acid (MMA) blood or urine test; it is the most specific and accurate for detecting B12 levels. We advise doing this as a part of your routine health checkups.

Recommended Daily Intake of Vitamin B-12

The following table shows the national recommended daily intake (RDI) of vitamin B12 according to different age groups, pregnancy, and breastfeeding:

In 2015, the European Food Safety Authority set their RDI of B12 for people over 15 years to 4 mcg and up to 5 mcg for pregnant and nursing mothers.

The overall bioavailability of vitamin B12 is said to be around 50% in healthy adults with normal gastrointestinal function. So we recommend taking high doses (at least 5 to 10 mg daily) so that your body can absorb as much as it needs and eliminate the excess in urine.

Vegan Sources of Vitamin B12

B12 Fortified Foods

The amount of vitamin B12 added to fortified foods may vary from brand to brand or country to country, so check food labels for nutritional information to learn how much of your RDI is fulfilled per serving and determine your supplement dosage.

Source: Beyond Meat by Open Grid Scheduler / Grid Engine is licensed under CC BY 2.0

1. Nutritional Yeast: Loved for the cheesy, umami flavor it adds to salads, soups, sauces, and vegan pasta dishes. Nutritional yeast is an excellent source of all nine essential amino acids, minerals, and vitamins.

When fortified with vitamin B12, nutritional yeast can deliver up to 15 mcg (630% DV) per serving size of 10g (2 tablespoons).

2. Plant-Based Meats: Not all plant-based meats can provide vitamin B12. The popular brands, Impossible Burger and Beyond Meat, are fortified with 3mcg (130%) and 2.4mcg (100%) of vitamin B12 per serving size of 113 grams.

In cases where B12-producing bacteria form a symbiotic relationship with vegan meat substitute mushrooms, particularly cremini mushrooms, you may enjoy small amounts of vitamin B12 from eating mushrooms.

3. Tofu
4. Vegan Cereals
5. Fruit Juice
6. Plant-Based Milk such as soy, cashew, oat, almond, or coconut milk.
7. Dairy-Free Yogurt
8. Marmite Yeast Extract

Vegan-Friendly Vitamin B12 Supplements

If your lifestyle is fast-paced or you aren’t diligent enough to track your daily consumption of vitamin B12 in fortified foods, then you can opt for supplements. Even persons eating a healthy, B12-rich vegan diet should take B12 supplements to narrow any nutrition gaps.

B12 supplements usually come in tablets, gummies, and sublingual forms in doses ranging from 500 mcg to 5,000 mcg.

The dosage of vitamin B12 supplement you choose should be determined by your age, health status, and whether or not you wish to rely on the supplement as a primary source of the vitamin.

Researchers recommend that people take 50–100 mcg of vitamin B12 daily or 2,000 mcg weekly if they are healthy and absorb nutrients efficiently. You can take a high-dose supplement if your lifestyle, age, or health status commands it, but you should first seek your doctor's advice.

One good thing about vitamin B12 is that it has a low potential for toxicity. So far, there are no known risks of having too much B12.

Final Words

Vitamin B12 deficiency isn’t only a vegan or vegetarian problem. Today, typical meat-eaters suffer from vitamin B12 deficiency for so many reasons.

“How is it possible for people who eat meat to be deficient in B-12?” you may be wondering. We suspect the following reasons:

1. Livestock animals on commercial farms don’t graze as much as they ought to.
2. Grazing soil or animal feed may be lacking in cobalt. Animals need cobalt to synthesize vitamin B12.
3. The B12-producing bacteria in meat and seafood can be damaged during cooking.

As a vegan, you shouldn’t have to worry about getting enough B12 so long as you load up on fortified foods and supplement wisely. As confirmed by a study in 2000, people who consume fortified breakfast cereals or B12 supplements have higher concentrations of the vitamin and are least likely to be deficient, compared with those who rely on meat for vitamin B12.

New research says water lentils (otherwise known as duckweed) may contain "approximately 750 percent of the US recommended daily value of the bioactive forms of vitamin B12 (per 100 grams of dry plant)."

Sources:

1. Beyond Meat’s Nutrition Facts - https://www.beyondmeat.com/en-US/products/the-beyond-burger 
2. Impossible Burger’s Nutrition Facts - https://faq.impossiblefoods.com/hc/en-us/articles/360018939274 
3. Carmel R. (2008). How I treat cobalamin (vitamin B12) deficiency. Blood, 112(6), 2214–2221. https://doi.org/10.1182/blood-2008-03-040253