title: Seasonal variation of vitamin A (retinol) status in older men and women.
abstract: OBJECTIVE
  The present study was undertaken to determine vitamin A status in 59 free-living (26 males, 33 females) healthy older persons (65-74 years) in winter and summer.
  
  
  METHODS
  Three-day dietary intake data for vitamin A along with carbohydrate, lipid and protein were collected during the summer (June-September) and again during the winter (November-March). In addition, retinol and its carrier proteins, retinol-binding protein (RBP) and transthyretin (TTR), were measured in the plasma in each season.
  
  
  RESULTS
  The mean vitamin A intake met the Canadian Recommended Intake (RNI) for both gender and season. However, probability analysis of dietary data revealed that 7 and 11% of males, and 8 and 14% of females, in summer and winter, respectively, were at risk of deficiency. None of the subjects in the present study exhibited biochemical evidence of vitamin A deficiency as determined by plasma levels of retinol and its transport proteins. Overall, the mean intake of vitamin A was significantly higher in males than in females; no seasonal effect was observed. On the other hand, the plasma levels of retinol and its carrier proteins were significantly lower in winter season than in summer, without any gender variation effect.
  
  
  CONCLUSIONS
  Although mean values for dietary intake and plasma concentration of vitamin A may indicate nutritional adequacy, a small proportion of an older population may be at nutritional risk. The prevalence of risk appears to be generally higher in the winter than in the summer season and in females than in males.
authors.affiliation: Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Canada.
authors.forename: T K
authors.initials: TK
authors.lastname: Basu
authors.forename: E A
authors.initials: EA
authors.lastname: Donald
authors.forename: J A
authors.initials: JA
authors.lastname: Hargreaves
authors.forename: G W
authors.initials: GW
authors.lastname: Thompson
authors.forename: E
authors.initials: E
authors.lastname: Chao
authors.forename: R D
authors.initials: RD
authors.lastname: Peterson
mesh_terms: D000368:Aged; D000375:Aging / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D005260:Female; D006801:Humans; D008297:Male; D011228:Prealbumin / Q000032:analysis; D012177:Retinol-Binding Proteins / Q000032:analysis; D054839:Retinol-Binding Proteins, Plasma; D012621:Seasons; D012727:Sex Characteristics; D014801:Vitamin A / Q000008:administration & dosage / Q000097:blood*
chemical_list: D011228:Prealbumin; D012177:Retinol-Binding Proteins; D054839:Retinol-Binding Proteins, Plasma; D014801:Vitamin A