HPLC assessment and multivariate predictability of serum retinol and α-tocopherol concentrations in adult female subjects

Antioxidant vitamins have been reported to protect against a variety of human malignances and multiple chronic degenerative diseases therefore it is important to understand factors that influence their blood levels. The present study was conducted to verify association of serum retinol and α-tocopherol levels with obesity, and to assess predictors of their serum concentrations in representative sample population of overweight/obese (n = 51) and normal weight (n = 26) apparently healthy adult female subjects recruited from typical urban area in Poland. Anthropometric measurements were taken from all participants who also completed a questionnaire on selected lifestyle factors. The serum concentrations of retinol and α-tocopherol were measured by fully validated Chromsystems diagnostic kit employing isocratic RPHPLC with switched wavelength UV detection. Intake of energy, fat, vitamin A and E and alcohol consumption were estimated by seven daily dietary records. Multivariate linear regression models were fitted in order to estimate the predictors of serum retinol and α-tocopherol concentration. There were no statistically significant differences in the average serum levels of retinol and α-tocopherol between overweight/obese and normal weight adult female subjects. Serum α- tocopherol concentrations were positively correlated with serum total cholesterol level (TChol) and body mass index (BMI), but inversely with total energy intake and past dieting behaviour. The TChol and total energy intake were identified as predictors of serum retinol levels. Intakes of fat and vitamin E and A, age, serum triglyceride concentration, smoking, alcohol consumption and physical activity were unrelated to serum levels of retinol or α-tocopherol. The main finding of this study is that obesity is not associated with decreased serum retinol and α-tocopherol levels. In addition, these results indicated that dietary intake of vitamin A and E are poor predictors for serum retinol or α-tocopherol concentrations. Serum levels of both these vitamins are primarily influenced by TChol, obesity, total energy intake and past dieting behaviour