Purpose: The purpose of this thesis project was to cross-validate a vitamin D-specific food frequency and lifestyle questionnaire (FFLQ) in active populations using both a biomarker and a 7-Day Food Diary as reference methods. Methods: This study was conducted using data collected previously in student-athletes using 25(OH)D as a biomarker of status (Study 1) and in healthy individuals using vitamin D intake estimates collected via 7-day food records as the intake marker (Study 2.) Study 1: FFLQ data was used to estimate vitamin D intake and ultraviolet B (UVB) exposure at leisure and via tanning bed use and compared to serum 25(OH)D concentrations via Spearman Correlation Coefficients. Backward linear regression was used to assess the relationship between estimated vitamin D intake and significant influential lifestyle factors, and vitamin D status. Study 2: FFLQ data was used to estimate vitamin D intake and compared to estimated vitamin D intake from 7-Day Food Records via paired t-test. Bland-Altman plots were used to visually display the differences between the two measurement techniques.
Results: Study 1: Data were available on male and female athletes from a variety of sports during fall (n = 54 male/32 female), winter (30 male/19 female), and spring (44 male/23 female) seasons. Serum 25(OH)D averaged 42.4 ± 15.5 ng/ml in fall, 27.9 ± 9.0 ng/ml in winter, and 35.0±15.5 ng/ml in the spring. Estimated total vitamin D intake from food and supplements averaged 800 ± 820, 1236 ± 1131, and 727 ± 977 IU per day for fall, winter, and spring respectively. Reported leisure sun exposure during these three seasons was 0.8 ± 0.7, 0.7 ± 0.5, and 0.6 ± 0.6 hours/day for fall, winter, and spring respectively. Serum 25(OH)D was not found to be associated with vitamin D intake from food or vitamin D intake from food and supplements, or reported leisure sun exposure during any season, but was consistently associated with BMI (r = –0.32 to –0.47), reported frequency of tanning bed use (r = 0.39) in the spring and supplement use in fall y (r = 0.28). Linear regression models reveled that in the fall BMI, sunscreen use, tanning bed use, total UV exposure per day explained serum 25(OH)D (R = 0.476). In winter, BMI was the only explanation, (R = 0.32) and in spring (R = 0.61), sunscreen, tanning bed use, and BMI accounted for 25(OH)D concentrations. Study 2: Data were available on 120 adults (n = 59 male/61 female.) Estimated FFLQ vitamin D intake was 183.5 ± 123.5 IU/day and estimated 7-Day Food Diary vitamin D intake was 120.9 ± 72.3 IU/day. The FFLQ estimated vitamin D intake was not found to be associated with estimated 7-Day Food Diary intake (r = 0.00.) Conclusions: The estimated vitamin D intake from the FFLQ was not found to be correlated with either serum 25(OH)D concentration (Study 1) or the estimated vitamin D intake from a 7-Day Food Diary (Study 2). These results suggest that the FFLQ estimated vitamin D intake from food and supplements is not a significant predictor of vitamin D status or actual vitamin D intake.
|Commitee:||Alexander, Brenda, Johnson, Evan|
|School:||University of Wyoming|
|Department:||Family & Consumer Sciences|
|School Location:||United States -- Wyoming|
|Source:||MAI 58/02M(E), Masters Abstracts International|
|Keywords:||Food, Frequency, Questionnaire, Validation, Vitamin D|
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