When you follow a vegan lifestyle, there are many questions that you probably dread. Where do you get your protein? Why don’t you eat dairy or eggs? How do you get your calcium if you don’t drink milk? If you are well-informed on vegan nutrition you can easily answer these questions with pride.

But, there is one question that delves a bit deeper, that is a much more difficult to answer, and threatens the view of many vegans that their lifestyle is a more natural way for humans to eat: Why aren’t there any plant-based sources of B12?

Every vitamin, mineral, or nutrient can be found in a modern-day plant-based diet, except for one. Vitamin B12 (or cobalamin) can not be found in any plant-based sources and is only found in animal products. This strikes a sore-spot for many vegans.

In practically every book or article that you read on vegan nutrition there are lengthy paragraphs on how and where you can find nutrients such as calcium and protein in a plant-based diet. These discussions are usually followed by a sentence such as this, “Vitamin B12 is vital for your health. Since you can only get B12 from meat or dairy products, if you follow a vegan diet, make sure to take a vitamin B12 supplement daily.”

After reading a statement like this, you may be wondering, but why? The answer to this question is difficult to find, but if you search the scientific literature long enough, you can find it.

To really understand why we can’t get vitamin B12 from a plant-based diet in modern-day society, we have to take a look at nature and a look back into our human history.

B12 is produced by “good” bacteria which are found in the soil and on plants. Every herbivore in nature gets its supply of B12 from consuming these bacteria on the plants they eat. These bacteria then make homes in the gut of the herbivores that eat them. Carnivores get their B12 by consuming the organs and thus the bacteria from their herbivore prey.

Our ancestors, whether you’re looking at several thousand years or just a few hundred years back into our past, didn’t wash the food they pulled from the ground. They ate the bacteria which produce B12 on the plant-foods they consumed and got an adequate supply of B12 daily.

In our modern-day society, bacteria isn’t found on our plant-foods for two reasons. First, the large number of pesticides, herbicides, and other chemicals used to treat our food doesn’t allow a large amount of this bacteria to grow in our soils. Second, we wash our food very well. So, in our modern-day diet, there is not enough of this good bacteria on our plant foods so we have to find other sources.

People who eat meat or vegetarians that eat dairy and eggs, can easily get their B12 from animal products. This is mainly because of contamination of the animal foods by the bacteria normally found in the gut of these animals.

Unfortunately for vegans, the only source of B12 is through a supplement. So when you pop that B12 pill, hopefully you’ll feel better knowing that you have to take it only because of our clean, modern-day culture and not because a vegan diet is fundamentally deficient!