Abstract
The present study compares the bioavailability of vitamin B12 (B12) of dairy products or synthetic B12, using the pig as an experimental model for humans. Eleven pigs were used in a cross-over design to assess the net portal drained viscera (PDV) flux of blood plasma B12 after ingestion of tofu (TF; devoid of B12), Swiss cheese (SC), Cheddar cheese (CC), yogurt (YG), and synthetic B12 (TB12; TF supplemented with cyanocobalamin), providing a total of 25 µg of B12 each. PDV blood plasma flow for SC and CC were higher than for TF and TB12 (p ≤ 0.04) whereas YG was higher than TF (p = 0.05). Porto-arterial difference of blood plasma B12 concentrations were higher for CC and TB12 than for TF and YG (p ≤ 0.04) but not different from SC (p ≥ 0.15). Net PDV flux of B12 was only different from zero for CC. However, the net PDV flux of B12 for CC was not different from SC or TB12. Cumulative net PDV flux of B12 for SC, TB12, and CC were 2.9, 4.4, and 8.3 µg 23 h post-meal, corresponding to a bioavailability of 11.6%, 17.5%, and 33.0%, respectively. In conclusion, CC had the best bioavailability of B12 among the tested dairy products or compared to synthetic B12.
Highlights
Animal products and by-products are the only natural source of vitamin B12 (B12 ) in human diets.Considering that B12 is synthesized exclusively by bacteria and archaebacteria, ruminant animals obtain the vitamin from synthesis by their ruminal microflora.The vitamin is further absorbed and stored in their body, which explain why the tissues and milk of these animals are especially rich in B12 .Among animal-derived products, milk stands out as an excellent source of B12
Arterial concentrations of B12 were not affected by dietary treatments (p = 0.18; Table 2) but a time effect was observed in which values gradually decreased throughout the 23 h profile period
To the best of our knowledge, the present study using a net portal drained viscera (PDV) flux approach to assess the amount of vitamin B12 absorbed from dairy products through the gastrointestinal tract is unique in scientific literature
Summary
Animal products and by-products are the only natural source of vitamin B12 (B12 ) in human diets. Among animal-derived products, milk stands out as an excellent source of B12. Milk intake was reported to be better correlated with B12 status than eggs, red meat, poultry, fish and seafood consumption [1,2]. Using a food-frequency questionnaire, Vogiatzoglou et al [3] showed that at similar intakes, dairy products have a greater impact on plasma concentrations of B12 than the above mentioned products, suggesting a better bioavailability of this vitamin from dairy products. Matte et al [4] reported greater bioavailability of B12 from milk than from the synthetic form (cyanocobalamin) present in most supplements.
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