Aphanizomenon Flos-aquae: A Source of Vitamin B12?

Dr. Michael Greger brought my attention to a paper published last year on the B12 activity of Aphanizomenon flos-aquae (also known as blue-green algae).

My write-up on the study is too long to post here, but it appears that Aphanizomenon flos-aquae might provide some vitamin B12 activity in humans. On the other hand, it did not succeed in lowering homocysteine to an ideal level whereas vitamin B12 supplements do succeed at doing so. At this time, it would be prudent not to rely on it for optimal health.

Click here for the entire update.

Vegan Essentials

4 Responses to “Aphanizomenon Flos-aquae: A Source of Vitamin B12?”

  1. Michael Greger, M.D. Says:

    Excellent analysis (as always)!

  2. Flo Says:

    There is a conflicting study regarding AFA algae as B12 source: http://www.ncbi.nlm.nih.gov/pubmed/17147452

    “The purified corrinoid-compound was identified as pseudovitamin B12 (an inactive corrinoid-compound for humans) by silica gel 60 TLC, C18 reversed-phase HPLC, ultraviolet-visible spectroscopy, and 1H NMR spectroscopy. The results suggest that the Aphanizomenon cells are not suitable for use as a vitamin B12 source, especially in vegans.”

  3. Paul Says:

    Effect of a Klamath algae product (“AFA-B12”) on blood levels of vitamin B12 and homocysteine in vegan subjects: a pilot study.

    Baroni L, Scoglio S, Benedetti S, Bonetto C, Pagliarani S, Benedetti Y, Rocchi M, Canestrari F.

    Department of Neurorehabilitation, Villa Salus Hospital, Mestre-Venice, Italy.

    Vitamin B12 is a critical nutrient that is often inadequate in a plant-based (vegan) diet, thus the inclusion of a reliable vitamin B12 source in a vegan diet is recommended as essential. Unfortunately, many natural sources of vitamin B12 have been proven to contain biologically inactive vitamin B12 analogues, inadequate for human supplementation. The aim of this non-randomized open trial was to determine whether supplementation with a natural Klamath algae-based product (“AFA-B12”, Aphanizomenon flos-aquae algae plus a proprietary mix of enzymes) could favorably affect the vitamin B12 status of a group of 15 vegan subjects. By assessing blood concentration of vitamin B12, folate, and more importantly homocysteine (Hcy, a reliable marker in vegans of their B12 absorption), the vitamin B12 status of the participants at the end of the 3-month intervention period, while receiving the Klamath-algae supplement (T2), was compared with their vitamin B12 status at the end of the 3-month control period (T1), when they were not receiving any supplement, having stopped taking their usual vitamin B12 supplement at the beginning of the study (T0). Compared to the control period, in the intervention period participants improved their vitamin B12 status, significantly reducing Hcy blood concentration (p=0.003). In conclusion, the Klamath algae product AFA-B12 appears to be, in a preliminary study, an adequate and reliable source of vitamin B12 in humans.

    PMID: 20108213 [PubMed – indexed for MEDLINE]

  4. Jack Norris RD Says:


    > Effect of a Klamath algae product (“AFA-B12″) on blood levels of vitamin B12 and homocysteine in vegan subjects: a pilot study.

    Sorry it took me so long to post and respond to this comment. I analyzed this study when it came out in 2009:


    I concluded that there was no reason to think that Klamath algae is a reliable source of vitamin B12.

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