Exploration of non-animal vitamin B12 sources in the UK and Ireland:a study on natural origins for vegetarian diets

Vitamin B12 (VB12) deficiency, prevalent among the growing vegetarians worldwide, leads to several serious health consequences, necessitating exploration of natural vegetarian-friendly sources of VB12. While some natural non-animal food sources have been reported to contain VB12, the concentration varies depending on sample species and environmental parameters. The knowledge regarding the VB12 content and forms in natural non-animal sources from the UK and Ireland is rarely reported. This study examined the VB12 content in commonly found natural non-animal eukaryote samples from the UK and Ireland, including 20 species of edible seaweed (72 samples), 10 species of mushrooms (16 samples), and 32 tea samples. The total VB12 levels (cyanocobalamin) was initially screened and quantified by the microbiological assay and followed by UPLC-MS/MS analysis of VB12 isoforms (cyanocobalamin, methylcobalamin, adenosylcobalamin, and hydroxocobalamin). Both quantification methods were optimised and validated in this study, demonstrating satisfactory characteristics and exceptional sensitivity, with the lowest limit of detections and limit of quantifications reported to date. Results indicate that species variation is the primary determinant of VB12 variability; the effects of harvest site, season, and sample source on the VB12 content of seaweed were species-specific; additionally, tea types and mushroom maturity stages influenced the VB12 content. Certain seaweeds and mushroom samples were found to contain considerably high levels of VB12, including the first report of high VB12 levels found in Osmundea pinnatifida. Notably, methylcobalamin emerged as the predominant form of VB12 in most seaweed and mushroom species; no pseudocobalamin was detected. Additionally, seaweeds such as Porphyra spp., Palmaria palmata, O. pinnatifida, and Ulva lactuca exhibited superior bioaccessibility. Overall, the findings of this study highlight the potential of non-animal food sources from the UK and Ireland as a valuable natural source of VB12 and potentially serve as a modifiable dietary factor to address VB12 deficiency among vegetarians.Thesis is embargoed until 31 July 2025.