Location: Food Components and Health LaboratoryTitle: Absorption and distribution kinetics of the 13C-labeled tomato carotenoid phytoene in healthy adults Author
|Moran, Nancy - The Ohio State University|
|Cichon, Morgan - The Ohio State University|
|Riedl, Kenneth - The Ohio State University|
|Rogers, Randy - University Of Illinois|
|Grainger, Elizabeth - The Ohio State University|
|Schwartz, Steven - The Ohio State University|
|Erdman, Johyn - University Of Illinois|
|Clinton, Steven - The Ohio State University|
Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/2/2015
Publication Date: 2/1/2016
Citation: Moran, N.E., Novotny Dura, J., Cichon, M., Riedl, K., Rogers, R., Grainger, E., Schwartz, S., Erdman, J., Clinton, S. 2016. Absorption and distribution kinetics of the 13C-labeled tomato carotenoid phytoene in healthy adults. Journal of Nutrition. 146:368-376.
Interpretive Summary: Tomato intake has been thought to be protective against prostate cancer since a Harvard publication reported reduced incidence of prostate cancer in men who consumed tomato products. A compound called lycopene, which is in the family of pigments called carotenoids, was first thought to be the active component. However, another carotenoid called phytoene is found in much lesser amounts in tomatoes but accumulates to similar levels in body tissues. The accumulation of this compound in body tissues despite its lower concentration in food suggests that the body may preferentially retain phytoene for health reasons. To date, very little is known about the body’s ability to absorb and distribute phytoene, therefore we conducted a study with specially tagged phytoene so we could follow it through human metabolism to determine how well it is absorbed, stored, and eliminated. Four adults consumed the tagged phytoene and provided blood samples for six weeks after dosing. The resulting data showed that the intestinal absorption of phytoene is approximately double that of the more common tomato carotenoid lycopene. Further, the elimination of phytoene happens more than twice as slowly as lycopene. As the roles of phytoene and lycopene are more clearly defined, dietary guidance regarding tomato, lycopene, and phytoene intakes will become more reliable. These results will be useful to scientists and health practitioners.
Technical Abstract: Phytoene is a tomato carotenoid which may contribute to the apparent health benefits of tomato consumption. While phytoene is a less prominent tomato carotenoid than lycopene, it is a major carotenoid in various human tissues. Phytoene distribution to plasma lipoproteins and tissues differs from lycopene, suggesting the kinetics of phytoene and lycopene differ. The objective of this study was to characterize the kinetic parameters of phytoene absorption, distribution, and excretion in adults, to better understand why biodistribution of phytoene differs from lycopene. Four adults (2 males, 2 females) maintained a controlled phytoene diet (1-5 mg per day) for 42 days. On day 14, each consumed 3.2 mg 13C-phytoene, produced using tomato cell suspension culture technology. Blood samples were collected at 0, 1-15, 17, 21, and 24 h and 2, 3, 4, 7, 10, 14, 17, 21, and 28 d post 13C-phytoene consumption. Plasma unlabeled and labeled phytoene concentrations were measured by UPLC-MS, and data were fit to a 7-compartment carotenoid kinetic model using WinSAAM 3.0.7 software. Subjects were compliant with a controlled phytoene diet, consuming 2.5+/-0.6 mg per day, resulting in average unlabeled plasma phytoene concentrations of 71+/-14 nmol per L. A maximal plasma 13C-phytoene concentration of 55.6+/-5.9 nM was achieved 19.8+/-9.2 h after consumption, and the plasma half-life was 2.3+/-0.2 d. Compared to previous results for lycopene, phytoene bioavailability was nearly double at 58+/-19%, the clearance rate from chylomicrons was slower, and the rate of deposition into and utilization by the slow turnover tissue compartment were nearly 3 times greater. Though only differing from lycopene by four double bonds, phytoene exhibits markedly different kinetic characteristics in human plasma, providing insight into metabolic processes contributing to phytoene enrichment in plasma and tissues compared to lycopene.