title: Association of protein intakes and variation of diet-scalp hair nitrogen isotopic discrimination factor in Papua New Guinea highlanders.
abstract: OBJECTIVE
  We present new nitrogen isotopic discrimination factor between diets and scalp hairs (Δ(15) NHair-Diet : δ(15) NHair - δ(15) NDiet ) for indigenous residents in three communities in the Papua New Guinea Highlands who consumed various amounts and qualities of protein. The Δ(15) N is important for precise evaluation of the dietary habits of human populations; in both contemporary and traditional lifestyles. Several hypotheses have been proposed regarding factors that affect Δ(15) N values, based largely on observations from animal feeding experiments. However, variations and factors controlling Δ(15) N in humans are not well understood, mainly due to the difficulty of controlling the diets of participants.
  
  
  METHODS
  These residents were studied because they have maintained relatively traditional dietary habits, which allow quantitative recording of diets. Δ(15) N was estimated by comparing hair δ(15) N values to mean dietary δ(15) N values calculated from the recorded intake of each food item and their δ(15) N values.
  
  
  RESULTS
  The results showed that: i) there was a significant difference in Δ(15) N among study locations (3.9 ± 0.9‰ for most urbanized, 5.2 ± 1.0‰ for medium and 5.0 ± 0.9‰ for least urbanized communities; range = 1.2-7.3‰ for all participants); and ii) estimated Δ(15) N values were negatively correlated with several indicators of animal protein intake (% nitrogen in diet: range = 0.9-7.6%).
  
  
  CONCLUSIONS
  We hypothesize that a combination of several factors, which presumably included urea recycling and amino acid and protein recycling and/or de novo synthesis during metabolic processes, altered the Δ(15) N values of the participants.
authors.affiliation: Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwanoha 5-1-5, Kashiwa, Chiba, 277-8562, Japan.
authors.forename: Yuichi I
authors.initials: YI
authors.lastname: Naito
authors.affiliation: Department of Human Ecology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-0033, Japan.|Tokyo Medical and Dental University, Yushima 1-5-45, Bunkyo-ku, Tokyo, 113-8519, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Morita
authors.affiliation: The Japanese Red Cross Akita College of Nursing, Nawashirosawa 17-3, Saruta, Kamikitate, Akita, Akita, 010-1493, Japan.
authors.forename: Kazumi
authors.initials: K
authors.lastname: Natsuhara
authors.affiliation: Department of Human Ecology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-0033, Japan.
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Tadokoro
authors.affiliation: The Research Institute for Languages and Cultures of Asia and Africa, Tokyo University of Foreign Studies, 3-11-1 Asahi-cho, Fuchu, Tokyo, 183-8534, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Baba
authors.affiliation: Faculty of Letters, Chiba University, 1-33 Yayoicho, Inage, Chiba, 263-8522, Japan.
authors.forename: Shingo
authors.initials: S
authors.lastname: Odani
authors.affiliation: Department of Human Ecology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-0033, Japan.
authors.forename: Eriko
authors.initials: E
authors.lastname: Tomitsuka
authors.affiliation: Graduate School of Biomedical Science, Nagasaki University, 1-12-4 Sakamoto, Nagasaki, 852-8523, Japan.
authors.forename: Katsura
authors.initials: K
authors.lastname: Igai
authors.affiliation: Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwanoha 5-1-5, Kashiwa, Chiba, 277-8562, Japan.
authors.forename: Takumi
authors.initials: T
authors.lastname: Tsutaya
authors.affiliation: Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwanoha 5-1-5, Kashiwa, Chiba, 277-8562, Japan.|The University Museum, The University of Tokyo, Hongo 7-3-1, Bunkyo, Tokyo, 113-0033, Japan.
authors.forename: Minoru
authors.initials: M
authors.lastname: Yoneda
authors.affiliation: Papua New Guinea Institute of Medical Research, PO Box 60, Goroka, Eastern Highlands Province 441, Papua New Guinea.|Federation University, Gippsland Campus Northways Road, Churchill, Victoria, 3842, Australia.
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Greenhill
authors.affiliation: Papua New Guinea Institute of Medical Research, PO Box 60, Goroka, Eastern Highlands Province 441, Papua New Guinea.
authors.forename: Paul F
authors.initials: PF
authors.lastname: Horwood
authors.affiliation: Papua New Guinea Institute of Medical Research, PO Box 60, Goroka, Eastern Highlands Province 441, Papua New Guinea.
authors.forename: Kevin W
authors.initials: KW
authors.lastname: Soli
authors.affiliation: Papua New Guinea Institute of Medical Research, PO Box 60, Goroka, Eastern Highlands Province 441, Papua New Guinea.
authors.forename: Suparat
authors.initials: S
authors.lastname: Phuanukoonnon
authors.affiliation: Papua New Guinea Institute of Medical Research, PO Box 60, Goroka, Eastern Highlands Province 441, Papua New Guinea.
authors.forename: Peter M
authors.initials: PM
authors.lastname: Siba
authors.affiliation: Department of Human Ecology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-0033, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Umezaki
mesh_terms: D000293:Adolescent; D000328:Adult; D000885:Anthropology, Physical; D002648:Child; D004044:Dietary Proteins; D005247:Feeding Behavior / Q000502:physiology*; D005260:Female; D006197:Hair / Q000737:chemistry*; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009587:Nitrogen Isotopes / Q000032:analysis*; D010219:Papua New Guinea / Q000453:epidemiology; D012535:Scalp / Q000502:physiology; D055815:Young Adult
chemical_list: D004044:Dietary Proteins; D009587:Nitrogen Isotopes
keywords: metabolism; nitrogen isotopic discrimination factor; protein quality; scalp hair