Content and Characteristics of Vitamin B12 in Some Seaweeds.

Abstract

SummaryThe vitamin B12 (B12) content in seven species of seaweed that are consumed frequently in Hokkaido, Japan, was microbiologically measured using Escherichia coil 215. Asakusanori (Porphyra tenera), maruba-amanori (Porphyra suborbiculata) and akaba-gin-nansou (Rhodo giossum pulcherum) showed higher B12 content than the other species, although the content varied greatly among samples in the same species. A bioautography on a thin-layer plate holding a mixture of silica gel and cellulose, differentiation of B12 and its analogues using a binding specificity of intrinsic factor and haptocorrin, and comparison of the B12 concentra tion determined by the radioisotope dilution assay method using the intrinsic factor as the B12-binding protein with that by the bioassay method, predominantly showed B12 in maruba-amanori and B12 analogues in wakame (Undaria pinnatifida) and akaba-gin-nansou. The B12 uptake of akaba-gin-nansou from artificial seawater was similar to that of asaku sanori that contained only B12. Key Words vitamin B12, seaweed, B12 analogue, bioassay, radioassay, B12 uptakeThe occurrence of vitamin B12 (B12) was believed confined to the animal kingdom until the early 1950s when the B12 content was found to be higher in some seaweeds than beef or fish meat (1). Accordingly, seaweeds were expected to be promising resources of B12 (2) because of their vast production in the world. Most seaweeds contain not only B12 analogues that are active in mammals, but also other * To whom correspondence should be addressed . B12 analogues (2). The biological and nutritional significance of B12 and its analogues in seaweeds have not been reported. However, only Dagnelie et al. reported a deleterious effect on mean corpuscular volume in vegetarian children with a tendency of B12 deficiency when fed some seaweeds including noni (Porphyra family) (3). The findings of Dagnelie et al. may be due to B12 analogues in the seaweeds. The purpose of this study was to get some clue as to the significance of B12 analogues in some seaweeds for human nutrition. For this reason, B12 content was assayed microbiologically using Escherichia coli 215. It responds to a wider variety of B12 and B12 analogues than any other test organism (4). We measured the B12 contents in some commercially available seaweeds that were consumed frequently in Japan. The structure of B12 and its analogues in maruba-amanori (Porphyra suborbiculata ), akaba-gin-nansou (Rhodoglossum pulcherum) and wakame (Und aria pinnatifida) were characterized.Asakusanori containing only B12 has been known to take up B12 from artificial seawater (5). The relationship between B12 content and B12 uptake by a seaweed was worth studying. The B12 uptake by akaba-gin-nansou, composing exclusively of B12 analogues, was measured and compared with that of asakusanori.

Feeding dried purple laver (nori) to vitamin B12-deficient rats significantly improves vitamin B12 status

“…These vitamin B 12 contents of the dried purple laver were markedly higher than those of other seaweeds (kelp, 0´1 mg, hijiki 0 mg, wakame, 0´6 mg; Resources Council, Science and Technology Agency, 1995); similar results have been reported by van den Berg et al (1988). Yamada et al (1997) reported that most of the vitamin B 12 in some seaweeds (wakame (Undaria pinnatifida) and akaba-gin-nansou (Rhodoglossum pulcherum)), may be cobamide-like vitamin B 12 analogues, which are inactive in mammals. Several studies have also reported that spirulina tablets (Spirulina sp.)…”

Vitamin B12 among Vegetarians: Status, Assessment and Supplementation

“…(also known as nori) contain relevant amounts of Cbl ranging from 32.3 to 63.6 μg/100 g [179]. In vitro tests are promising, but there are not enough human clinical trials to consider the use of seaweed as favorable in vitamin provision [180,181]. In a clinical trial of six vegan children, the daily use of nori seaweed seemed to prevent Cbl deficiency, measured via serum Cbl [182].…”

Vitamin B12-Containing Plant Food Sources for Vegetarians

“…The release of free Vitamin B 12 from the purple laver significantly decreased to approximately 2.5% at pH 7.0 (as a model of severe atrophic gastritis) [57]. Edible purple laver predominantly contains coenzyme forms (5′-deoxyadenosylcoblamin and methylcobalamin) of Vitamin B 12 or hydroxocobalamin (or both) [57,58,59]. …”