title: Seasonal variations in dietary intake affect the consistency of dietary assessment.
abstract: BACKGROUND
  Nutritional epidemiology studies are usually based on one dietary assessment without taking into account the season in which the interview is taken or adjusting for the difference in reporting dietary intake in different seasons. The semiquantitative food frequency questionnaire has become the primary questionnaire method for measuring dietary intake in epidemiological studies. The aims of this report were (a) to evaluate the effect of season on dietary intake as measured by a semiquantitative food frequency questionnaire (FFQ) conducted twice: once in summer and a second time in winter; and (b) to assess the effect of the differences in dietary intake on biochemical and anthropometric seasonal related changes, such as serum cholesterol and body mass index (BMI).
  
  
  METHODS
  The study population consisted of 94 male industrial employees who participated in clinical biochemical and physical examinations as well as evaluation of their dietary intake twice a year. Dietary intake was assessed using the semiquantitative FFQ that included 96 items and was conducted by a personal interview.
  
  
  RESULTS
  We found a significant increase in the intake of selected nutrients in winter as compared to summer as well as an increased intake of animal fat-containing foods such as meat and dairy products. Significant correlation coefficients were shown between the increase in dietary intake of saturated fat and the increase in BMI, serum total and LDL cholesterol. The increase in dietary cholesterol was significantly and positively correlated with the increase in serum total and LDL cholesterol.
  
  
  CONCLUSIONS
  Although FFQ are designed to assess average yearly food intake, we identified significant seasonal changes in dietary intake as measured by FFQ. These changes have a health impact on our population.
authors.affiliation: The S. Daniel Abraham International Center for Health and Nutrition, Ben-Gurion University of the Negev, Faculty of Health Sciences, Beer Seva, Israel. dshahar@bgumail.bgu.ac.il
authors.forename: D R
authors.initials: DR
authors.lastname: Shahar
authors.forename: N
authors.initials: N
authors.lastname: Yerushalmi
authors.forename: F
authors.initials: F
authors.lastname: Lubin
authors.forename: P
authors.initials: P
authors.lastname: Froom
authors.forename: A
authors.initials: A
authors.lastname: Shahar
authors.forename: E
authors.initials: E
authors.lastname: Kristal-Boneh
mesh_terms: D000328:Adult; D015992:Body Mass Index; D008078:Cholesterol, LDL / Q000097:blood; D004041:Dietary Fats / Q000097:blood; D004435:Eating / Q000502:physiology* / Q000523:psychology*; D005247:Feeding Behavior / Q000502:physiology / Q000523:psychology; D006801:Humans; D007557:Israel / Q000453:epidemiology; D007899:Leisure Activities / Q000523:psychology; D008297:Male; D008875:Middle Aged; D015596:Nutrition Assessment; D012621:Seasons; D011795:Surveys and Questionnaires
chemical_list: D008078:Cholesterol, LDL; D004041:Dietary Fats