Bioavailability of Vitamin B12 from Dairy Products Using a Pig Model

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.