🍄Cobalamin (B12)

Cobalamin is a B-vitamin and an essential nutrient. It is made neither by large animals, nor by plants, but by microbes. Cobalamin can be absorbed by large organisms which we then eat ourselves.

Sources

Vegan whole food sources include mushrooms (ex: Shiitake), seaweed (dried green laver/aonori, dried purple laver/nori), and water lentils (which are also 20% to 40% protein by weight). https://youtu.be/QHvRArWglRY Fortified sources include nutritional yeast and cereal. Spirulina is not a source of cobalamin. https://veganhealth.org/vitamin-b12/vitamin-b12-plant-foods/ https://www.vegansociety.com/resources/nutrition-and-health/nutrients/vitamin-b12/what-every-vegan-should-know-about-vitamin-b12 "Dried green laver (Enteromorpha sp.) and purple laver (Porphyra sp.) are the most widely consumed edible algae, and they contain substantial amounts of Vitamin B12 (approximately 63.6 μg/100 g dry weight and 32.3 μg/100 g dry weight, respectively" https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4042564/

Recommendation

It's highly recommended for everyone (even non-vegans) to supplement cobalamin using cyanocobalamin, as it is the type with the best evidence supporting it. The reason why everyone should supplement is because a very large portion of the general population is not meeting the recommended dietary intake of cobalamin, despite them not being vegan, and it is unrealistic to try to consume only whole food sources of cobalamin that are not also carcinogenic or otherwise destructive to overall health. It's recommended to take at least 2,000 mcg weekly or 50 mcg daily. If you're over 65 it's recommended to take 1,000 mcg daily. Like most things, it is unhealthy to intake excessive amounts of cobalamin. https://nutritionfacts.org/topics/vitamin-b12/ https://www.healthline.com/health/food-nutrition/vitamin-b12-side-effects#see-a-doctor

"40% of 3,000 adults under age 50 [this includes non-vegans] had blood levels of vitamin B12 low enough to cause problems" https://www.webmd.com/food-recipes/news/20030618/vegetarian-diet-b12-deficiency

"39 percent of the general population may be in the low normal and deficient B12 blood level range, and it was not just vegetarians or older people. This study showed no difference in the B12 blood levels of younger and older adults. Most interestingly there was no difference between those ate meat, poultry, or fish and those who did not eat those foods. The people with the highest B12 blood levels were those who were taking B12 supplements and eating B12 fortified cereals." https://baltimorepostexaminer.com/carnivores-need-vitamin-b12-supplements/2013/10/30#sthash.RerFgkfc.dpuf http://ajcn.nutrition.org/content/71/2/514.full If you're averse to supplementing, it may interest you to know that you almost certainly already are supplementing. The supplement is just being given to the animal first before you eat them. 90% of cobalamin supplements are given to animals. https://baltimorepostexaminer.com/carnivores-need-vitamin-b12-supplements/2013/10/30#sthash.RerFgkfc.dpuf https://vegetarianism.stackexchange.com/questions/1540/how-common-is-it-for-the-livestock-industry-to-supplement-b12