Differences between plasma and adipose tissue biomarkers of carotenoids and tocopherols

Biomarkers of dietary exposure or nutritional status are sought actively to overcome limitations of traditional dietary methodology. We compared plasma and adipose tissue biomarkers for carotenoids and tocopherols. The data consisted of samples from 91 men and 122 women, ages 45-70 years, from the control group of the European Community Multicentre Study on Antioxidants, Myocardial Infarction, and Cancer of the Breast (EURAMIC) Study. Pearson correlations between plasma and adipose tissue measurements for beta-carotene, lycopene, and alpha-tocopherol adjusted for smoking status displayed low, although significant, correlations of 0.39, 0.24, and 0.39, respectively. The correlation was further stratified by sex. After being corrected for measurement error using deattenuation factors obtained from a reproducibility study, the stratified correlation coefficients were as high as 0.80 for beta-carotene in men, 0.62 for lycopene in women, and 0.52 for alpha-tocopherol in women. In addition, plasma and adipose tissue measurements from the myocardial infarction (MI) subset of the EURAMIC study population were used to evaluate the odds of MI, adjusting for confounders. We found that the concentration of lycopene in plasma was not positively associated significantly with MI (odds ratio, 1.78; P = 0.26). Adipose tissue lycopene, in contrast to reports elsewhere on the total population, showed an inverse association with MI (odds ratio, 0.62; P = 0.15). These results suggest that plasma and adipose carotenoids represent different markers for nutritional status and cannot be used interchangeably in epidemiological and dietary validation studies.