Vegetarians, vegans and b12 deficiency

I had a lot of great feedback from my last article on vegetarian dietary needs. One such point is that I might have come across a bit harsh on vegetarians themselves. If so this was not my intention. So I’d like to highlight, although being a vegetarian means you may need to be more aware of nutrient deficiencies.


It can be a very healthy diet and although it is very difficult to predict, some studies even show Seventh Day Adventists who ate little or no meat showed increases in health and longevity.


This isn’t to say avoiding meat caused them to live longer, just that a meat-free diet can still be healthy in the long-term. However, nutrient deficiencies must be taken care of otherwise the benefits can be quickly nullified.


Which brings us onto B12 deficiency. This little vitamin is extremely important for overall health and well-being, and the most common deficiency in vegans.


B12 deficiency symptoms can include exhaustion, rapid heartbeat, brain fog, confusion and weakness. Long-term deficiency can also mimic signs of dementia such as memory loss and difficulty thinking and reasoning.


B12 is almost exclusively available in animal foods and as we age, our ability to digest and absorb it reduces. The tiny epithelial cells of the stomach decrease, limiting our ability to transport b12 after digestion. Meaning b12 deficiency is actually more common than you’d expect, especially among vegans and vegetarians. (1)


This is something we want to be really proactive about because vitamin B12 is critical. Its deficiency can take years or even decades to manifest. By this point irreversible nervous system degeneration could of already occurred, and we don’t want that. The absorption of vitamin B12 is unique among nutrients and there’s a very unusual rule.


That rule is you can only absorb enough from a single meal to last you a day.


So how do you make sure you’re getting enough b12?


If you are a vegetarian, eggs are actually quite a poor source of B12. Dairy is a good source, but it needs to be eaten on a daily basis.


What if you’re vegan or avoid dairy? Here you have to tread carefully because there are a lot of vegan sources of things that look like vitamin B12 but don’t behave as vitamin B12 in the body.

These are known as b12 analogs or pseudo b12, molecules which have a very similar chemical structure to that of vitamin B12, but which shouldn’t be substituted for consumption. On the contrary, they are potentially harmful, since these replace the important B12 transport molecules within the body, thus hindering the absorption of actual vitamin B12.

If we look at the research, true vitamin B12 is only found in certain mushrooms like black trumpet, chanterelle, and shiitake. Or in certain edible algae like nori which is also called laver. It’s also found in chlorella, although chlorella supplements vary enormously in their vitamin B12 content and shouldn’t be relied upon. (2,3)

If you’re vegan, you can either use black trumpet, chanterelle, or shiitake mushrooms and eat one-hundred-gram serving three times a day. Or a much simpler way is adding green or purple nori as it is much higher in b12 than mushrooms.

Four to eight grams of nori in a single meal will supply you with a day’s worth of b12.

Seaweed Salad

If you are really concerned about your b12 levels, I recommend getting tested and looking into oral supplementation or b12 injections to quickly bring your levels back up.