Abstract: The usual dietary sources of Vitamin B12 are animal-derived foods, although a few plant-based foods contain substantial amounts of Vitamin B12. To prevent Vitamin B12 deficiency in high-risk populations such as vegetarians, it is necessary to identify plant-derived foods that contain high levels of Vitamin B12. A survey of naturally occurring plant-derived food sources with high Vitamin B12 contents suggested that dried purple laver (nori) is the most suitable Vitamin B12 source presently available for vegetarians. Furthermore, dried purple laver also contains high levels of other nutrients that are lacking in vegetarian diets, such as iron and n-3 polyunsaturated fatty acids. Dried purple laver is a natural plant product and it is suitable for most people in various vegetarian groups.
Alex’s Notes: Vitamin B12 is a water-soluble vitamin necessary for the proper functioning of the nervous system, and for the formation of blood. It is intimately involved in the metabolism of every cell of the human body, and affects DNA synthesis and regulation, fatty acid synthesis, and energy production. Deficiency of this vitamin can cause severe and irreversible damage to the nervous system, and levels only slightly below normal can cause fatigue, depression, memory problems, mania, and psychosis.
The thing is, vitamin B12 is the only vitamin not found in plants, with meats and animal products being the main dietary source. So what’s the problem? I love meat, dairy, and eggs. Well, the deficiency among vegetarians was estimated as 62%, 25%–86%, 21%–41%, and 11%–90% in pregnant women, children, adolescents, and elderly subjects, respectively, by review of the 18 reports evaluating vitamin B12 status of vegetarians. Vegans were even worse off, and at the risk of pissing some readers off, there is absolutely ZERO reason to be vegan from a health standpoint. Vegetarians can do fine since they don’t eliminate all animal products, but veganism is a death sentence.
So for all you Super Human vegetarians out there, hopefully you are smart about your B12 status. It’s tricky because all the “fortified” breakfast cereals you probably don’t eat (which is good), so if you want alternatives to supplements, then listen up. Despite what you may read on the internet, spinach, soybeans, broccoli, asparagus, and kimchi are all negligible sources. Fortunately, some mushrooms may hold promise. The fruiting bodies of black trumpet and golden chanterelle mushrooms contained high levels of Vitamin B12 (1.09–2.65 μg/100 g dry weight), and the consumption of approximately 50 g of dried shiitake mushroom fruiting bodies could meet the RDA for adults (2.4 μg/day). Algae is another great source, but only dried green laver and purple laver (laver is nori, by the way) which contain approximately 63.6 μg/100 g dry weight and 32.3 μg/100 g dry weight, respectively, of vitamin B12.
Basically, nori seaweed is your best bet. It is commonly formed into a sheet and dried for use in sushi and can be readily found in many stores. You would need to consume approximately 4 grams daily to get the RDA, and each 9 x 3 cm2 sheet is about 0.3 grams. That’s a lot of seaweed. Fortunately, you are vegetarian and not vegan, meaning that you still consume eggs, dairy, or fish depending on your preferences. These have substantial B12, so perhaps just supplement with a couple sheets of seaweed, and be sure to eat your animal products.