In vivo enrichment of chicken eggs with 14C‐B12 for determining vitamin B12 bioavailability in humans

Abstract

Animal source foods such as eggs are the only natural dietary source of vitamin B12 but there is limited information on its bioavailability from these sources. The objective was to test the feasibility of enriching eggs in vivo with sufficient 14C‐B12 for use in human bioavailability studies. 14C‐B12 was biosynthesized using Salmonella enterica, purified and injected into the thigh muscle of a laying hen. Eggs were collected 21 d, pooled, scrambled and cooked. A serving of egg containing ~0.7 μg 14C‐B12 (~30 nCi) was fed to each of 10 healthy humans after an overnight fast. 14C, detected by accelerator mass spectrometry, first appeared in plasma at 3–4 h after dose and peaked at 7–10 h, with 5–40% appearing in urine in the first 24 h. Fecal 14C analyses in progress will enable calculation of % bioavailability of B12. We conclude that this protocol can be used for human B12 bioavailability studies. Funded by the American Egg Board.