B12-Containing Plant Food Sources for Vegetarians (2014 article/overview)

[Korn]

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4042564/
PMCID: PMC4042564

A short excerpt:

A survey of naturally occurring and high Vitamin B12-containing plant-derived food sources showed that nori, which is formed into a sheet and dried, is the most suitable Vitamin B12 source for vegetarians presently available. Consumption of approximately 4 g of dried purple laver (Vitamin B12 content: 77.6 μg /100 g dry weight) supplies the RDA of 2.4 μg/day. In Japan, several sheets of nori (9 × 3 cm2; approximately 0.3 g each) are often served for breakfast. A large amount of nori can be consumed as certain forms of sushi (vinegared rice rolled in nori). In particular, hand-rolled sushi made by wrapping rice and fillings with nori is easy to prepare and facilitates the consumption of a large amount of nori. When dried purple laver was treated by toasting until the laver’s color changed from purple to green, the toasting treatment did not affect the Vitamin B12 contents [57]. Dried purple lavers could also be a suitable food item for integration in Italian, French, and other forms of western cuisine. Dried purple laver is also a rich source of iron and n-3 polyunsaturated fatty acids (Figure 4). Dried purple laver is a natural plant product; therefore, it is suitable for most vegetarian groups. Among edible mushrooms, relatively high levels of Vitamin B12 were detected in the commercially available shiitake mushroom fruiting bodies, but the Vitamin B12 content significantly varies (1.3–12.7 μg/100 g dry weight), which is significantly lower than that found in dried purple laver. However, the dried shiitake mushroom fruiting bodies (per 100 g) contain 18.9 mg of Vitamin D2 (ergocalciferol) and 2.0 mg of iron [63], which are also nutrients that vegetarian diets tend to lack. Thus, the use of these plant-based food sources can significantly improve the nutrient imbalance in vegetarian diets to reduce the incidence of Vitamin B12 deficiency in vegetarians.

[Korn]

The above overview suggests the following:
Nori is the most suitable B12 supplement source for vegetarians presently available. This is surprising, for several reasons. See other threads in this section for more info about nori (especially dried nori), but it seems that the four researchers behind this study may think that nori is more suitable than certain other 'non-supplement' B12 sources without actually writing it. I haven't seen anything suggesting that B12 from even fresh nori is more suitable as a B12 source than supplement than ...B12-supplements!
It also states that "dried purple laver is a natural plant product; therefore, it is suitable for most vegetarian groups", but I don't think that 'most vegetarian groups' have a philosophy of nut using clothes, bicycles, internet or other 'non-natural' ingredients in their lives?
The abstract also says that "relatively high levels of Vitamin B12 were detected in the commercially available shiitake mushroom fruiting bodies, but the Vitamin B12 content significantly varies (1.3–12.7 μg/100 g dry weight), which is significantly lower than that found in dried purple laver".


As expected, Jack Norris has posted the following:

http://jacknorrisrd.com/vitamin-b12-in-nori/

A review paper by the Watanabe group suggests that vegans can rely on nori for vitamin B12. I strongly advise against this.

The ever-returning dilemma in discussions like this, is... why aren't vegan organisations or others performing more tests on the plants that are claimed to contain some kind of B12? I totally agree that it's important to kill false myths about reliable B12-sources, but let's not forget that it's silly and wrong to state that no algae/plants etc contain reliable B12 unless it's proven. To prove that, one would have to perform a lot of tests - hundreds of thousands, actually, dye to the many plant species/subspecies on earth, and each of them would have to be tested with actual B12 activity, not only see if there's B12 in them. The Vegan Society made a B12/chlorella test once, a few years ago, and concluded that "it seems likely that chlorella is an effective source of B12, but due to the small number of people completing the trial we still cannot definitely confirm this and therefor cannot recommend chlorella can be relied upon as the sole source of B12". So, again (just like so many experts already agree in): more tests are needed!

ETA - the main person behind the study which in the late 90s actually documented that the B12 found in spirulina and algal health food mainly was inactive B12 analogues is the same Watanabe which he now describes as someone who writes a report one cannot trust because another report came to another conclusion.

http://www.researchgate.net/publicat...rulina_tablets

For the records, I don't recommend anyone to rely on studies on B12/MMA rats. When the goal is to find out how certain products work in the human body, humans should be tested on, not animals. Not only am I against using animals for such activities, I don't see why they don't test the same products on humans instead. I'm sure many people with low B12 levels gladly would participate in studies on real B12 activity in algae/plant based products (like eg this study).