The basics

Vitamin B12 has many roles. It helps convert carbohydrates, fats and proteins into energy. It's required for making our DNA, which means it's especially important during growth. It's also required for red blood cell production, and it helps to maintain the protective coating around our nerves called the myelin sheath.

In some high-protein foods we consume, there's an amino acid called methionine. The breakdown of methionine creates another amino acid by-product called homocysteine. This homocysteine can damage the delicate linings of our arteries, trigger heart disease, and negatively impact bone health. Vitamin B12 helps to get rid of this damaging homocysteine.

Recommended intake

The official Recommended Dietary Allowance (RDA) for adults over 14 years of age is 2.4 mcg per day. This may seem like a very small amount! Some recent studies suggest that 4 - 7 mcg may help protect us against high levels of homocysteine.

The Institute of Medicine has concluded, “no adverse effects have been associated with excess vitamin B12 intake from food and supplements in healthy individuals”. In short, there are no known risks to having more vitamin B12 than our body may need.

Food sources

Fermented foods, sprouts, mushrooms, seaweed, spirulina, meat substitutes, raw plant foods, and breakfast cereals are all possible food sources for vitamin B12. Although some sources say vitamin B12 is present in such foods, these are most often inactive analogues and aren't considered reliable sources for this essential vitamin.

Combining both food intake and supplementation is likely the most effective way to get all of the vitamin B12 that we need.

Types of supplements

When it comes to B12 supplementation, we'll see either the cyanocobalamin or methylcobalamin form. Let's briefly review both.


This form of vitamin B12 has been more extensively researched. It's the most stable form of vitamin B12 and as the name suggests, it contains a teeny amount of cyanide. Cyanide is a potentially harmful chemical but is present to help stabilize the vitamin. This has been a source of hesitation for those purchasing this form of vitamin B12 supplement. However, cyanide is naturally present in nature. For example, 1 tablespoon of flax seeds has 30 times as much cyanide, and this amount has been deemed insignificant by toxicologists. After consuming cyanocobalamin, our body removes and detoxifies the cyanide. It then naturally converts the cyanocobalamin to methylcobalamin, the more active form of vitamin B12. Note that this conversion may be more difficult in those who smoke or have kidney failure. If this is the case, a direct source of methylcobalamin may be best.


This form of vitamin B12 is less stable than cyanocobalamin. Since less research has been done on this form, less is known about its effectiveness. Methylcobalamin also tends to be more expensive, and we know that many factors, such as our age, impact how much we're able to absorb.

How to get enough

Getting enough vitamin B12 is especially important for those of us following a plant-based lifestyle. There are a few ways to make sure our intake is adequate:

  1. Food: consume 3 servings of vitamin B12 fortified foods, with each serving offering at least 2 micrograms (mcg) of vitamin B12. Some foods that may be fortified include plant-based milk, vegan meat substitutes, nutritional yeast, and breakfast cereals. Be sure to read the food labels to determine how much vitamin B12 is in the product, if at all. Note that it's best if these foods are eaten at different times of the day. This is because vitamin B12 receptors can become full with as little as 1.5 mcg doses. In other words, if high amounts of vitamin B12 are taken at a time, our body simply can't absorb it all. As mentioned above, it may be wise to combine both dietary intake with a supplement, as the amount of vitamin B12 in these foods can vary.

  2. Daily supplementation: each day, take a cyanocobalamin supplement that offers at least 25 mcg of Vitamin B12. When taking a multivitamin supplement, be sure to check the label as this amount or more may be provided. Some experts suggest that a larger dose of 500 - 1000 mcg per day may be required for adults over the age of 65 due to the reduced ability to absorb vitamin B12 from foods.

  3. Biweekly supplementation: twice a week, take a cyanocobalamin supplement that offers 2000-2500 mcg of vitamin B12. Although our daily needs for vitamin B12 is much less than this, the body only absorbs a fraction of what's offered by a supplement. This dose is higher than suggested for daily supplementation, because the less frequently vitamin B12 is taken, the higher the dose we need is.

baked zucchini fries with two dips
Our baked zucchini fries feature nutritional yeast, a source of vitamin B12.

Commonly asked questions

What supplement type should we take? Liquid supplements, tablets that dissolve under the tongue, as well as regular tablets to swallow or chew are all suitable.

What if we take too much? When we take larger doses, the body only absorbs a fraction of what's offered because the receptors become full and can't absorb any more. With this in mind, there's no concern with taking too much. Additionally, vitamin B12 is a water-soluble vitamin, meaning any extra we have above and beyond what our body needs will simply be excreted in our urine.

What if we miss a dose? The body is phenomenal at re-absorbing vitamin B12. It shouldn't be a cause for concern if we happen to go a period of time without supplements. For those of us who've been vegan for a few months and haven't been supplementing, now's a great time to start!

What do deficiency symptoms look like? Short-term deficiencies can be remedied. Long-term deficiencies on the other hand can cause irreversible damage. Early symptoms of deficiency include weakness, fatigue and mood changes. These can be easily confused for other causes aside from vitamin 12 deficiency, so it's important to supplement regardless. Avoid relying on symptoms to indicate if intake is low if possible.

Doesn't our body make vitamin B12? Indeed, our body has been thought to make some vitamin B12 naturally. This amount isn't enough to meet our needs, though, and tends to be made too far down in our digestive tract to be absorbed,


  1. The recommended intake of vitamin B12 for adults is 2.4 mcg per day. For older adults, the recommendations are much higher.
  2. Foods alone are not reliable sources of vitamin B12. Supplementation is often recommended to be combined with food intake.
  3. Vitamin B12 supplements come in the form of cyanocobalamin and methylcobalamin. Choosing which form to take will depend on your needs, lifestyle,  and current medical conditions.