title: Regional differences in end-stage renal disease and amount of protein intake in Japan.
abstract: OBJECTIVE
  We recently showed regional differences in the incidence of end-stage renal disease (ESRD) within Japan, which is generally ethnically homogenous, suggesting that factors other than genetic may contribute to the difference. We examined regional differences in the amounts of dietary nutrient intake, especially protein in our search for an explanation.
  
  
  METHODS
  Annually, the Japanese Society for Dialysis Therapy reports the numbers of patients entering maintenance dialysis in each prefecture of Japan. We used these numbers from 1984 to 2002 to calculate the annual ESRD incidence in each of 12 regions of Japan. The regional differences were analyzed in relation to the amounts of nutrient intake reported annually by National Nutrition Survey in corresponding regions for these 19 years. Each year, approximately 15,000 subjects from 5000 households in randomly selected 300 districts were included to obtain a representative sample of the entire population of Japanese in a manner of age, sex, and body mass matched.
  
  
  RESULTS
  There were marked regional differences in the annual ESRD incidence and small regional differences in dietary intake of each nutrient. Multiple regression analysis showed that the annual ESRD incidence was negatively correlated with energy intake (r = -0.65, F = 240, n = 228) and positively correlated with animal protein intake (r = 0.25, F = 30). Across 12 regions in the values averaged for 19 years in each region, however, the incidence of ESRD was negatively correlated only with the amounts of energy intake (r = -0.74, F = 12, n = 12), but not with animal protein (r = 0.07, F = 0.04).
  
  
  CONCLUSIONS
  The present study, relating regional differences between ESRD dynamics and the amounts of nutrient intake in a nationwide population of Japan, revealed that the renal protective effects of dietary restriction of protein, suggested by animal models of progressive nephropathies but yet unproved by large-scale clinical trials, remained unestablished even on a macro level of whole Japan through mapping approaches.
authors.affiliation: Department of Internal Medicine and Pathophysiology, Nagoya City University Graduate School of Medical Sciences, Mizuho-ku, Nagoya, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Motokawa
authors.forename: Michio
authors.initials: M
authors.lastname: Fukuda
authors.forename: Wataru
authors.initials: W
authors.lastname: Muramatsu
authors.forename: Kinya
authors.initials: K
authors.lastname: Sengo
authors.forename: Nobuo
authors.initials: N
authors.lastname: Kato
authors.forename: Takeshi
authors.initials: T
authors.lastname: Usami
authors.forename: Atsuhiro
authors.initials: A
authors.lastname: Yoshida
authors.forename: Genjiro
authors.initials: G
authors.lastname: Kimura
mesh_terms: D004044:Dietary Proteins / Q000009:adverse effects*; D002149:Energy Intake / Q000502:physiology*; D005502:Food / Q000009:adverse effects; D006801:Humans; D015994:Incidence; D007564:Japan; D007676:Kidney Failure, Chronic / Q000453:epidemiology* / Q000209:etiology / Q000503:physiopathology
chemical_list: D004044:Dietary Proteins