Dr. Tan's research group is interested in tracking the movement and metabolism of nutrients and dietary bioactive compounds (DBCs) in human body, which is essential for understanding the functions of these nutrients and DBCs. Our current research focuses on the bioavailability, distribution and whole-body kinetics of retinoids and carotenoids. We are interested in how different conditions, such as chronic diseases, or techniques, such as encapsulation, may improve the bioavailability and change the kinetics. 

Retinoids

Carotenoids
Retinoids are a class of compounds that are related chemically to vitamin A, a critical vitamin involved in vision, growth, immune function, regulation of cell proliferation and differentiation, etc. ​Vitamin A deficiency (VAD) is a significant public health problem in South Asia and Africa, affecting primarily young children and pregnant women. VAD is the leading cause of preventable blindness in children and increases the risk of infectious diseases and death from severe infections. 
Carotenoids are the yellow, orange, and red pigments found in fruits and vegetables and they have antioxidant functions. Some carotenoids, such as alpha- and beta-carotene, can be converted to vitamin A in the body, and therefore are called provitamin A carotenoids. Some others, such as lycopene, lutein, and zeaxanthin, have no vitamin A activity but possess special functions for the body.

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Research Projects

Vitamin A Metabolism and Supplementation in Neonates

Little is known about the metabolism of vitamin A in neonates. In collaboration with researchers from Pennsylvania State University, this NIH-funded project aims to study the whole-body metabolism and kinetics of vitamin A in neonatal rats as well as the effects of different forms of vitamin A supplementation on the kinetics.

Obesity's Influence on Lycopene Bioavailability

Lycopene, a carotenoid phytochemical, is known for its free radical scavenging potential exerting antioxidant action. Despite the potential of lycopene to influence mechanisms underpinning obesity and cardiometabolic diseases, the lipophilic nature of lycopene may limit its functionality. In this project, we are using Sprague-Dawley rats as the animal model to test the hypothesis that adiposity blunts the metabolic kinetics, circulation, and distribution of lycopene.

Encapsulation on Bioavailability of VA & Beta-Carotene

Nutritional Quality of Microgreens
In this project, we are developing supramolecular guest-host structures, including starch-guest inclusion complexes, as delivery systems for vitamin A and beta-carotene, such that these nutrients can be protected against the adverse environment, and their bioavailability may be increased.
​Microgreens are young and tender vegetable greens, and represent an exotic class of specialty crops. This project seeks to optimize postharvest conditions to improve the nutritional and sensorial quality, shelf life, and microbial food safety of microgreens grown in Alabama.

Age-mediated Lutein Pharmacokinetics

Lutein functions as an antioxidant in the body and accumulates in the macula of the eye to protect against light-initiated oxidative damage. Its decreased status or absence in the eye has shown to be a major risk factor for age-related macular degeneration (AMD), the leading cause of visual loss in people > 50 years old. The detailed pharmacokinetic profile of lutein has not been elucidated yet. The study will use Sprague-Dawley rats and compartmental modeling to establish a pharmacokinetic model of lutein and to evaluate whether the bioavailability of lutein, its delivery to the eye and its elimination are altered by aging.

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