What is Vitamin B12?
Vitamin B12 is also known as cobalamin. It is an essential vitamin for red blood cell formation, neurological function and DNA synthesis. When metabolised, it exists as several forms including methylcobalamin and 5-deoxyadenosylcobalamin.
What are the Sources of Vitamin B12?
Vitamin B12 is naturally found in animal products such as meat, poultry and fish. To a lesser extent it is also found in dairy products. Common plant foods generally do not have vitamin B12. However, recent analyses have found it in fermented beans (tempeh), mushrooms, seaweed products (nori and laver) and algae.
Similar to ionised table salt, some foods are fortified with vitamin B12. These include breakfast cereals, plant-based milk, bread, pasta and nutritional yeast. However, it is important to check the brand as some may not use fortification. Labels will say vitamin B12 directly while others may say ‘cyanocobalamin’ or ‘B vitamins’.
Vitamin B12 supplements can be bought at pharmacies or drug stores. They are often included in multivitamins. In Australia and the US, over-the-counter supplements can be bought. Higher doses require a prescription from a physician.
A Common Misconception
Before we go any further, I want to clear up any confusion regarding the natural sources of B12 and its implications.
A common, misinformed argument against the plant-based diet is, “If vitamin B12 is more abundant and naturally found in animal products (compared to plant foods), then obviously humans were meant to consume meat.”
Let’s look into the scientific literature to see why this is an ill-informed statement.
All animals, plants and fungi are incapable of cobalamin production. The only life form that produces the vitamin are certain types of bacteria that exist in soil and water. Naturally, we would acquire this from the soil (through plants) or the water we drink. However, modern industry standards has led us to use chemicals such as chlorine to sanitise the water supply. While this prevents infections, it unfortunately also kills off our natural source of vitamin B12. This is why plants have minimal levels of vitamin B12.
So if that’s the case, then why do animal products have lots of B12?
Naturally, animals can get vitamin B12 by grazing in dirt that has the bacteria in it. Herbivores can ingest the bacteria found on the plants they eat. The bacteria proliferates and becomes part of the animal’s gut flora allowing it to produce vitamin B12 internally. However, as described above, these mechanisms are also disrupted by our sanitation standards and antibiotic use in the farming industry.
The reason why animals still have high levels of vitamin B12 is because they are fed with vitamin B12 supplemented feeds. This means that omnivores who receive their B12 from meat is actually getting it via an indirect supplemental chain (that is understandably, often not made known to the general public).
Vitamin B12 deficiency is a condition that can occur in both plant-based and omnivore diets. It is not merely just a vegan problem. From my experience as a medical student on placement, I have seen plenty of patients who’s blood results showed incidental B12 deficiency. They did not have any major metabolic disorders or drug interactions that would explain why. They were also not on a vegetarian or vegan diet.
Vitamin B12 Deficiency
The reason why we all make a fuss about vitamin B12 is because of vitamin B12 deficiency. As the name suggests, it is a condition defined by low levels of B12 in the body. The main cause is low dietary intake but others include malabsorption, intestinal disorders and drug interactions.
Vitamin B12 deficiency can potentially result in severe and at times, irreversible damage to the brain and nerves. Symptoms can range from fatigue, imbalance, breathlessness to depression, memory loss and neurological impairment.
The condition is preventable by sustaining an adequate amount of vitamin B12 through diet and supplements.
How to Supplement Vitamin B12 on a Plant-Based Diet
Eating a plant-based diet is a risk factor for vitamin B12 deficiency, simply because plant foods are lacking in B12 (as described above). Dairy products also do not have high levels of vitamin B12 and so vegetarians may also be at risk.
Fortunately, there are many ways we can ensure good levels of vitamin B12 on a plant-based diet.
Firstly, vitamin B12 supplements are necessary for those on a plant-based diet. Current literature suggests using supplements in the form of cyanocobalamin as there is insufficient quality evidence to support other forms such as methylcobalamin. Studies have shown no adverse effects associated with excess vitamin B12 intake from supplements in healthy individuals. We recommend consulting your family physician before starting any supplement.
After ensuring a daily supplementation of vitamin B12, we recommend eating foods fortified with the nutrient. Nutritional yeast and plant-based milks would be the easiest to consistently consume. However, just remember to check the brand and ensure that it does fortification.
The reason why we recommend supplementation first and then eating plant foods with naturally occurring or fortified B12 is because the latter may not be sufficient. The Academy of Nutrition and Dietetics considers plant and algae sources unreliable and recommends supplements instead. Although we love our nutritional yeast, we certainly don’t eat it every day or in enough amounts to cover our daily recommended vitamin B12.
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