Eggs As a Source of Bioavailable Vitamin B12
Obesity and Metabolism Research Unit
2008 Annual Report
1a.Objectives (from AD-416)
The objective of the research is to determine the bioavailability of vitamin B12 from chicken eggs. The term bioavailability refers to the percentage of a nutrient, in this case vitamin B12, within a food that is actually absorbed into the body during the digestive process. This is contrasted with the percentage of the nutrient that passes through the digestive tract and is excreted without being absorbed by the body. The hypothesis to be tested is that a high percentage of the vitamin B12 in egg is bioavailable, thus indicating that eggs are a good source of dietary vitamin B12.
1b.Approach (from AD-416)
Egg enriched with vitamin B12 labeled with a radioactive tag (carbon 14) will be cooked and fed to healthy human volunteers. The amount of the carbon-14 labeled vitamin B12 that is excreted in the stool (unabsorbed vitamin B12) will be compared with the amount of carbon-14 labeled vitamin B12 that appears in the blood and urine (absorbed vitamin B12). From these measurements, the fraction or percentage of vitamin B12 absorbed (bioavailability) will be calculated. The study will be carried out in 10 human volunteers and the mean bioavailability of vitamin B12 from egg will be calculated and reported. Documents Trust with the American Egg Board. Log 32483.
The goal of this project is to enrich eggs in vivo with radioactively labeled vitamin B12 to a level that allows us to feed the enriched eggs to humans and determine how much of the vitamin B12 is digested and absorbed into the body. Importantly, sensitive technology available at the Lawrence Livermore National Laboratories allows us to measure very low amounts of radioactive vitamin B12. Sufficient labeled eggs have been produced to feed ten human subjects. One has completed the study and sufficient B12 was detected in serum, urine and feces to model absorption; four more subjects have been recruited. NP107, Component 5, Health Promoting Properties of Plant and Animal Foods.