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13C and 15N abundance of plasma and saliva protein reflect protein intake from vegetable and animal products
Author(s) -
LIU YUQIU,
SHRIVER TIMOTHY C.,
SCHOELLER DALE A.
Publication year - 2008
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.22.1_supplement.868.12
Subject(s) - omnivore , saliva , trophic level , vegan diet , chemistry , food science , biology , zoology , medicine , biochemistry , ecology , predation
Self‐reported dietary intake is often biased. Therefore there is a need for objective biomarkers of diet. We investigated whether isotopic compositions of human protein reflected the proportion of plant and animal protein intake of individuals consuming U.S. foods. We recruited nine each omnivore, lacto‐ova vegetarian, and strict vegan healthy adults. Food frequency questionnaires were administered to assess protein intake. Plasma and saliva protein specimens were analyzed using an isotope ratio mass spectrometry equipped with an elemental analyzer. For plasma protein samples, vegans could be distinguished from omnivores in both 13 C (−21.6‰ ± 0.5 vs. −19.3‰ ± 0.5, p < 0. 01) and 15 N (8.0‰ ± 0.5 vs. 9.0‰ ± 0.3, p < 0.01) abundances. Lacto‐ova vegetarians were significantly different from vegans for both 13 C and 15 N abundances. For saliva protein, vegans could be clearly distinguished from omnivores in 13 C (−21.5‰ ± 0.6 vs. −19.6‰ ± 0.7, p < 0. 01) and trended in 15 N (6.6‰ ± 0.7 vs. 7.3‰ ± 0.7, p = 0.02). The 13 C abundances of omnivores were close to values predicted for US foods, but values for vegans contained more 13 C than predicted suggesting carbon exchange between macronutrients via intermediary metabolic pathways. The 15 N differences displayed the expected trophic level effect. In conclusion, human plasma and saliva 13 C and 15 N values both reflected the proportion of animal protein in the U.S. diet. Supported by Dairy Management, Inc.