Vegans should consider supplementing with vitamin B12, since it is not readily available in a plant-based diet. Both methylcobalamin and cyanocobalamin are effective as supplements of B12.
What is vitamin B12 and why do I need it?
Vitamin B12 is an essential water-soluble vitamin commonly known as cobalamin. Methylcobalamin and 5-deoxyadenosylcobalamin are the active forms in the body while cyanocobalamin is the common supplemental form. It is the only water-soluble vitamin that can be stored in the liver for many years .
Vitamin B12 assists in making red blood cells and DNA, protects neural cells, and ensures proper fat and protein metabolism. It is critical in all stages of life, especially during pregnancy and lactation to support proper development for the baby.
Deficiency of vitamin B12 can lead to anemia, fatigue, weakness, and more serious neurological changes. For babies, signs of low vitamin B12 include failure to thrive and developmental delays . Vitamin B12 deficiencies can be treated, however, you should be aware that large amounts of folic acid may prevent proper diagnosis of the deficiency.
How much vitamin B12 do I need?
The National Academy of Medicine (NAM) publishes the official Recommended Dietary Allowance (RDA) for vitamin B12 :
- All adult women: 2.4 mcg per day
- During pregnancy: 2.6 mcg per day
- During lactation: 2.8 mcg per day
The NAM notes that only newly absorbed vitamin B12 is transported to the developing baby across the placenta . That means that regardless of your B12 intake prior to conception, you should still supplement during pregnancy. It is also critical while breastfeeding, as vitamin B12 is transferred to the milk.
The recommendation from the NAM is widely accepted but has not been revised since 1998. A more recent research paper made a case for daily intake of 4-7 mcg of vitamin B12, citing a result of improved biomarkers . These details don’t seem to make a significant difference in the recommendation for supplementation, as you’ll read below.
Can I get enough vitamin B12 from a vegan diet?
Likely, the answer is ‘no’. Vitamin B12 is made by a certain bacteria, not by plants or animals . That bacteria, however, lives in the intestines of many animals, which is why meat and animal by-products have a high amount of vitamin B12. Before our modern-day industrialized agriculture, it was present in soil and a plant-based diet could have had adequate amounts of vitamin B12.
Today, some foods such as cereals, soy milk, and nutritional yeast are sometimes fortified with vitamin B12. Check the nutritional label to find out, but keep in mind that these are not considered reliable sources, so supplementing is still recommended.
How much vitamin B12 should I supplement with?
Supplementing with vitamin B12 is cheap and easy. But depending on the source, the exact recommended amount varies greatly. This is largely due
Depending on the source, form, and other nutrients present in the body, we may be absorbing anywhere from 0.5% to 60% of the vitamin B12 that we consume .
Don’t be surprised when you see large amounts in supplements, such as 250 mcg or even 2,500 mcg of vitamin B12. The reason for this is that our body’s receptors can only process around 1 to 2 mcg of vitamin B12 at a time and 1% of the remaining intake . So if your supplement has 250 mcg, you’re getting around 1.5 + (248.5 × 0.01) = 4 mcg.
From the discussion above on how much vitamin B12 you need, 250 mcg comes out to be the recommended daily intake of supplemental vitamin B12.
Weekly supplementation is also an option. As vitamin B12 can be stored in the liver, we do not require daily intake. The weekly recommended intake is 2,500 mcg of vitamin B12.
More is ok too. There are no known risks for taking in too much vitamin B12, either from food sources or supplements . So taking in too much is not harmful, but maybe wasteful, as excess vitamin B12 gets peed out.
Which form of vitamin B12 supplement is best?
There is no research available to show that a lozenge or sublingual supplement is better absorbed than the pill form of vitamin B12 . Pick whichever version you prefer, but don’t be tricked into thinking that one type is better than another.
Cyanocobalamin is cheap, effective, and is easily converted by our bodies to the active form of vitamin B12. Only individuals with chronic cyanide intoxication (from some tobacco and alcohol) need a different type of supplement.
A recent study addressed the difference between methylcobalamin, the body’s active form, and cyanocobalamin, the synthetic form, and found that methylcobalamin is more bioavailable . It is more expensive but, technically, we can supplement with a smaller amount, although these values have not been quantified.
Another consideration is that you need intrinsic factor, a protein secreted by your stomach, to properly absorb vitamin B12 in your large intestine . For most people, this is not an issue, but some have a condition called pernicious anemia, which prevents this secretion and therefore leads to malabsorption of vitamin B12. Intrinsic factor can be found in some supplements containing vitamin B12.
You may not have a diagnosis of pernicious anemia, but if you are taking a daily or weekly supplement that contain cyanocobalamin and your blood tests show a vitamin B12 deficiency, consider switching to methylcobalamin. That was my decision, based on a low serum vitamin B12 result over 5 years ago, and I have been taking methylcobalamin from Metagenics ever since.
Ultimately, the choice between supplementing with cyanocobalamin or methylcobalamin if yours – both are effective options!
- Vitamin B12 supplementation is necessary for all vegans.
- Your daily supplement should have at least 250 mcg of vitamin B12 or you can take 2,500 mcg weekly.
- Cyanocobalamin is a cheap and effective form of vitamin B12.
- Methylcobalamin with intrinsic factor can be supplemented instead if you have reason to believe that you have malabsorption of vitamin B12.