title: You are not what you eat during physiological stress: Isotopic evaluation of human hair.
abstract: Variation in δ(13) C and δ(15) N values can be assessed to understand not only diet, but also the influence of physiological factors on an individual. The metabolic balance of an individual can impact isotopic signals in tissues that are forming during the periods of metabolic stress. Fluctuating δ(15) N values are associated with physiological stressors that alter an individual's metabolism such as infection, injury, or pregnancy. This study examines variation in δ(13) C and δ(15) N values along sequentially segmented hair in both modern and archaeological individuals. Subjects with an observable skeletal pathology, known chronic illness, or evidence of pregnancy were compared with controls exhibiting no evidence of physiological stress. The results on hair samples from individuals from 19(th) century Belleville, Ontario, four modern cadavers (two with cancer and two sudden deaths), and two living pregnant women indicate that δ(15) N values are approximately 1‰ higher in individuals with a pathological condition (e.g., infection, fracture, or cancer) and are 1‰ lower during pregnancy, whereas δ(13) C values show less variability. Higher nitrogen values may represent the recycling of nitrogen derived from the breakdown of existing proteins in the body (catabolism), whereas lower δ(15) N values are related to increased utilization of dietary and urea nitrogen for tissue synthesis during pregnancy. These findings suggest that short-term fluctuations of δ(15) N values may be the result of changes in an individual's metabolic balance, and that metabolic imbalance poses a confounding factor to ancient dietary studies when using rapidly growing tissues such as hair.
authors.affiliation: Department of Anthropology, McMaster University, Hamilton, ON, Canada, L8S 4L9.
authors.forename: Lori
authors.initials: L
authors.lastname: D'Ortenzio
authors.affiliation: Department of Anthropology, McMaster University, Hamilton, ON, Canada, L8S 4L9.
authors.forename: Megan
authors.initials: M
authors.lastname: Brickley
authors.affiliation: Department of Anthropology, McMaster University, Hamilton, ON, Canada, L8S 4L9.|School of Geography & Earth Sciences, McMaster University, Hamilton, ON, Canada, L8S 4L9.
authors.forename: Henry
authors.initials: H
authors.lastname: Schwarcz
authors.affiliation: Department of Anthropology, McMaster University, Hamilton, ON, Canada, L8S 4L9.
authors.forename: Tracy
authors.initials: T
authors.lastname: Prowse
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000885:Anthropology, Physical; D002247:Carbon Isotopes / Q000032:analysis* / Q000378:metabolism; D002648:Child; D004032:Diet; D005260:Female; D006197:Hair / Q000737:chemistry*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009587:Nitrogen Isotopes / Q000032:analysis* / Q000378:metabolism; D011247:Pregnancy / Q000378:metabolism; D013312:Stress, Physiological / Q000502:physiology*
chemical_list: D002247:Carbon Isotopes; D009587:Nitrogen Isotopes
keywords: hair; physiological stress; stable isotopes