B12: A Bacteria-Based (Not Meat Based) Vitamin
“If those on plant-based diets don’t get enough vitamin B12, levels of an artery-damaging compound called homocysteine can start to rise in the bloodstream and may counteract some of the benefits of healthy eating.”
Dr Michael Greger M.D., The Vitamin Everyone on a Plant-Based Diet Needs, NutritionFacts.org
Dr Greger has a lot to say about how essential it is to get enough B12. The good doctor is such an enthusiastic cheerleader for the plant-based lifestyle that when he starts talking about a potential problem with the diet it is worth taking notes. Colleen is equally serious about the need to supplement with B12.
What is B12, why does it matter, how much do we need, and where does it come from?
B12 is synthesised by bacteria in the soil or in the lower intestine where it is reabsorbed back into the body. Only bacteria have the enzymes needed to synthesise B12.
Humans only need minute amounts of B12, around 5 to 10 micrograms (mcg) per day, but that tiny amount is crucial for normal functioning of the brain, nervous system and blood production. It is critical to metabolism, especially DNA synthesis and regulation. Vitamin B12 helps to lower levels of homocysteine, which supports prevention of heart disease and stroke. B12 deficiency can also cause blindness, dementia and irreversible nerve damage. It is not a problem to take excess B12 as it is water-soluble.
B12 can get reabsorbed from the lower intestine. It can also be stored in the liver, sometimes for years. However, the primary way to obtain B12 is through ingestion of materials that contain B12. The animals people eat, like us, have minute traces of essential B12. The other option is to eat foods or supplements fortified with biologically active B12 from commercial bacteria production.
We used to get our B12 from the same place the animals we eat used to get it. We ingested soil or faeces on the vegetation we ate that came out of the ground. These days most of us eat such well-washed produce that any trace of B12 left on our store brought vegetables is unlikely. Also, many farm animals are now kept inside warehouses and feed grain or other feed, so like us the only way they can get trace amounts of B12 into their system is if their food is fortified. Chickens are no longer pecking up dirt or pigs digging up roots, and cows are increasingly moved into ‘intensive’ (factory) systems where they are no longer pulling up soil with their grass; they are eating grain in feed lots.
Note: It is not just vegans who may potentially have a problem with B12 deficiency. The primary issue is absorption not consumption. Many vegans can go for decades because they are getting trace amounts from other sources or their digestive system is really good at reabsorption. Most of the people who develop B12 deficiency eat animals on a regular basis, so even though meat has trace amounts, it won’t mean much if you have a problem absorbing nutrients. However, the best insurance is to take a supplement, which is really what I should be doing.