As you may know, vitamins are typically associated with having a dedicated purpose. For example, vitamin A nurtures our vision, and vitamin C improves our immune system. However, the way our body benefits from different vitamins is much more sophisticated. When we look at how vitamins boost all kinds of bodily functions and mechanisms, vitamin B12 can be seen as a real powerhouse. It helps in the creation of DNA (1), blood, and nerve cells and is vital for a healthy brain and a robust immune system.
Consequently, a vitamin B12 deficiency carries all types of symptoms such as megaloblastic anemia, fatigue, weakness, constipation, loss of appetite, weight loss, depression, dementia, and soreness of the mouth or tongue. However, such a deficiency develops very slowly (typically over several years), as the liver can store up to five years worth of B12, and we only excrete around 0.1% of that amount each day.
How modern hygiene standards eradicated our natural B12 intake
B12 deficiency is much less an issue related to one's veganism and, rather, an issue attributed to our modern lifestyle. Gorillas, our closest relatives, get their B12 fix by involuntarily eating soil contaminated with fecal matter when munching on plants. However, contemporary vegan mainly eats commercially farmed crops that are power-washed and grown in cobalt-deficient soil. (Cobalt is a prerequisite for bacteria to be able to produce b12).
The natural approach is not always the best, but possible!
Fundamentally speaking, it seems that the natural way for us to get B12 is by consuming unwashed vegetables and unfiltered water. However, these unsanitized resources may also be covered in harmful pesticides and bacteria, such as salmonella and E.coli. So while natural is usually better, in this case, it is not always the case.
But that doesn't mean you can't go natural. For example, one of the plant-based foods that are rich in Vitamin B12 is Tempeh. Though the amount of vitamin B12 "can be highly varied (0.07 to 12.4 mcg/100 g tempeh) because the presence of vitamin B12 producing bacteria has been mostly coincidental or due to contamination." Tempeh has been "regarded as the richest plant-based source of vitamin B12." (2) If you adopt a plant-based diet and want to go natural, eat plant foods rich in vitamin B12 every day like tempeh, fortified plant milk, cereal, and nutritional yeast.
B12 is also known as cobalamin. There are different types of cobalamin, with the most prominent ones being cyanocobalamin and methylcobalamin. One contains a methyl molecule, the other a cyanide molecule. Cyanocobalamin is the most common type of B12. If you check the ingredients of your B12 supplement, you will read cyanocobalamin 99.9% of the time. It is a cost-effective synthetic version of B12 that cannot be derived naturally. Methylcobalamin is found in nature, and some argue that it may have a better absorption rate.
However, studies are contradictory: This study (3) found that people absorbed 49% of cyanocobalamin and only 44% of methylcobalamin. Another study (4) found that methylcobalamin may be retained better within our bodies, as urinal excretion of cyanocobalamin was three times higher.
Ultimately, the difference in resorption rate is not something to worry about, as a vitamin B12 pill typically contains around 150 mcg of B12, which is 60 times the RDA. Thus, if you're particularly frugal, you may even want to consider splitting pills in half, which is perfectly fine.
For example, when you consume a supplement, "only about 10 mcg of a 500 mcg oral supplement is actually absorbed in healthy people." So, if you are supplementing with 500mcg vitamin B12 per day, you will have enough vitamin B12. However, some prefer to take about 2000-2500mcg vitamin B12 per week, and that would give you enough B12 for a week as well. For proper use of vitamin B12 supplements, consult with your doctor or dietitian further in case there are things to consider.
Great news: Duckweed for Fundamentalist
Scientists have recently discovered the first bioactive, whole food plant source of B12 in a plant known as duckweed or water lentil. Besides the methylcobalamin mentioned above, they also identified the presence of adenosylcobalamin and hydroxocobalamin (two other bioactive forms of B12). 100 grams of the dry plant material contains around 750 percent of the RDA for B12.