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UBC Theses and Dissertations

Development of a vitamin B12 fortified yoghurt and its efficacy on vitamin B12 status in older adults Melo, Larisse


Vitamin B12 (B12) is an essential nutrient required for optimal energy metabolism and nervous system functioning. Adults aged >50 years are at risk of impaired B12 digestion and absorption and are recommended to consume B12-fortified foods and/or supplements, i.e. sources of free B12. The general consensus is that B12 has high bioavailability from dairy sources; therefore, developing a fortified dairy product represents a promising strategy to fill a market niche and improve B12 status in older adults. This research thesis consists of three main phases, with the following objectives: (I) to identify the most suitable method for the analysis of added B12 in yoghurts; (II) to develop B12-fortified yoghurts and assess shelf-life stability; and (III) to assess the efficacy of consuming one daily portion of B12-fortified, versus unfortified yoghurt on the B12 status of healthy older adults. For objective I, I developed a High-Performance Liquid Chromatography method and compared its performance to that of RIDASCREEN®, an immunoassay. I found that RIDASCREEN® was the most suitable method for measuring B12 in yoghurt, given its lowest level of quantitation (0.5 μg/L). For objective II, the shelf-life stability of methylcobalamin (MeCB), a naturally-occurring B12 form, and cyanocobalamin (CnCB), the synthetic B12 form, added to yoghurts either in isolated or encapsulated form was tested by measuring total B12 concentrations in yoghurts for 8 weeks. Results indicated that CnCB was a stable fortificant throughout yoghurt shelf-life, and isolated MeCB was stable up until week 4. For objective III, I performed an 8-week double-blind, randomized controlled intervention trial. Yoghurts were fortified with 50 μg MeCB. B12 status was measured at baseline, weeks 4 and 8 using serum total B12 concentration. In a total of 66 participants (aged 50-74y), a significant time-treatment interaction was found (p<0.001). After 4 weeks, serum total B12 concentration increased by 47% in the fortified group, and 8% in the control group, with no changes between weeks 4 and 8. This study brings novel findings to applied food science and human nutrition, by showing the feasibility of developing a B12-fortified yoghurt, which was efficacious in increasing serum total B12 concentration of older adults.

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