Mechanisms of dietary micronutrients and personal characteristics of the human body are intricately complicated. These mechanisms, however, can be easily interpreted through appropriate mathematical relationships. The present study aims to detect the statistically significant impact of personal characteristics and diet on plasma concentrations of retinol and beta-carotene using statistical modeling. The present analyses indicate that age, sex, smoking habit, quetelet, vitamin use, consumed calories, fiber, and dietary beta-carotene are statistically significant factors on plasma beta-carotene levels. On the other hand age, sex, smoking status, consumed fat, and dietary beta-carotene are significant factors on plasma retinol. These analyses indicate that changes in the variances of plasma beta-carotene and retinol are non-constant. Impacts of personal characteristics and dietary factors on human plasma concentrations of retinol and beta-carotene are explained based on mathematical relationships. These analyses support many earlier researches findings. However, the analyses also identify many additional casual factors that explain the means and variances of plasma beta-carotene and retinol, which earlier researches have not reported.
