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Page 20
Volume 05
Journal of Clinical Nutrition & Dietetics
ISSN: 2472-1921
JOINT EVENT
June 17-18, 2019 London, UK
Nutrition World 2019
Euro Obesity 2019
June 17-18, 2019
&
26
th
World Nutrition Congress
15
th
Euro Obesity and Endocrinology Congress
Is frying oil a dietary source or an endocrine disruptor? Anti-estrogenic effects of polar compounds from
frying oil in rats
Yu-Shun Lin
1
, Shui-Yuan Lu
2
, Hai-Ping Wu
1
, Chi-Fen Chang
1
, Yung-Tsung Chiu
3
, Hui-Ting Yang
1
and
Pei-Min Chao
1
1
China Medical University, Taiwan
2
Taiwan Agricultural Chemicals and Toxic Substances Research Institute, Taiwan
3
Taichung Veterans General Hospital, Taiwan
Statement of the Problem:
The objective was to investigate endocrine-disrupting effects of polar compounds from
oxidized frying oil. Estrogenicity of polar compounds was tested with a rat uterotrophic bioassay. Dietary oxidized
frying oil (containing 50% polar compounds) or polar compounds isolated from it were incorporated into feed
(in lieu of fresh soybean oil) and fed to ovariectomize rats, with or without treatment with exogenous ethynyl
estradiol. Exogenous estrogen restored uterine weight, and caused histological abnormalities (stratified epithelia
and conglomerate glands) as well as proliferation of uterine epithelial cells. However, tamoxifen or polar compounds
reduced these effects. Furthermore, tamoxifen or polar compounds down-regulated uterine mRNA expression of
estrogen receptor (ER)-target genes, implicating reduced ER activity in this hypo-uterotrophic effect. Inhibition
of ER signaling and mitosis by polar compounds were attributed to reduced MAPK and AKT activation, as well
as a reduced ligand binding domain-transactivity of ER
α
/
β
. We concluded polar compounds from frying oil are
potential endocrine-disrupting chemicals, with implications for food and environmental safety.
Methodology & Theoretical Orientation:
In the study, a uterotrophic bioassay in rodents, suggested by EPA test
guidelines (OPPTS 890. 1600), was used to test
in vivo
estrogenicity of polar compounds from oxidative frying oil.
To eliminate interference from endogenous estrogens or the hypothalamic-pituitary-gonadal axis, ovariectomized
mature female rats were used. Chemicals with agonistic or antagonistic activities toward natural estrogens are
assessed based on uterine weight or uterotrophic response. In addition, an
in vitro
ER reporter assay was conducted
to verify (anti)estrogenic effects of saponifiables (hydrolysis released fatty acids) from polar compounds (compared
to fresh oil).
Findings:
Polar compound fraction (PC) in oxidized frying oil is anti-estrogenic; the hypouterotrophic effect of PC
was attributed to suppress ER signaling; PC inhibited epithelial proliferation by reduced MAPK and AKT activation
and PC reduced ligand binding domain transactivity of ER
α
/
β
.
Conclusion & Significance:
This study provided evidence of the endocrine-disrupting potential of polar compounds
from OFO. Inhibition of ER signaling and mitosis in the uterus by polar compounds were attributed to reduced
MAPK and AKT activation, as well as a reduced ligand binding domain-transactivity of ER
α
/
β
. Despite food safety
limits of a maximum of 25% polar compounds in many countries, the potential and relative risk for endocrine
disruption remains to be determined.
Biography
Yu-Shun Lin has completed his Doctor Degree in China Medical University in Taiwan. Currently, after finishing his PhD, he is pursuing his Postdoctoral research.
He has expertise in studying the safety of oxidative frying oil, researching the topic for a long time. His research finding evidence shows for the first time that
oxidative frying oil influences estrogen receptor function having the endocrine disrupting potential.
U101059851@cmu.edu.twYu-Shun Lin et al., J Clin Nutr Diet 2019, Volume 05