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Percent bioavailability of vitamin B12 from eggs is inversely proportional to egg total B12 consumed
Author(s) -
Garrod Marjorie G,
Miller Joshua W.,
Green Ralph,
Buchholz Bruce A.,
Calvert Christopher C.,
Allen Lindsay H.
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.31.5
Vitamin B12 bioavailability from egg was determined using 14 C‐B12 synthesized and purified from Salmonella enterica . Two laying hens were injected i.m. with 400 nCi and 480 nCi 14 C‐B12, respectively. Eggs were collected for 21 d, pooled for each hen, scrambled, and cooked in individual servings containing ~30 nCi 14 C‐B12 each. Total B12 was 1.4 μg in servings from hen 1 and 2.6 μg in servings from hen 2. Healthy, fasting volunteers received 1 serving from either hen 1 (n=4) or hen 2 (n=4). Plasma was collected from 0–12 h, then daily for 7 d. Complete stool and urine were collected for 7 d. 14 C was measured by accelerator mass spectrometry. 14 C in plasma, which likely represents 14 C‐B12 absorbed intact, first appeared at 3–4 h after dosing and peaked at 7–10 h. Cumulative excretion of 14 C in urine, which likely represents degradation products of 14 C‐B12, ranged from 5.1–62.0% of the dose. Dose recovered in stool ranged from 24.7–74.1%. Bioavailability was calculated as intake minus excretion in urine and feces. Overall % bioavailability was 35.3 ± 16.4%. % bioavailability from egg containing 1.4 μg total B12 was 48.8 ± 10.8% and 21.7 ± 4.5% from eggs containing 2.6 μg total B12. We conclude eggs are a good source of B12 but there is a substantial fall in efficiency of absorption within the normal range of B12 intake reflecting the limit of the physiological absorptive mechanism for B12. Funding: American Egg Board