Volume 40, Issue 3, November 2015, Pages 876–885
Highlights
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- The estrogenic potential of Polish cow's milk was evaluated by the yeast estrogen bioassay.
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- Significant estrogenic activity was detected in 50% of milk samples after deconjugation.
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- Deconjugation is an obligatory step to reveal overall estrogenic activity of milk.
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- Positive correlation was found between fat content and estrogenic activity.
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- Human dietary intake of estrogens with milk may be higher than serum estrogen levels.
Abstract
Milk
contain compounds acting through the estrogen receptor signaling. The
still open question whether such estrogens pose a risk for human health,
encouraged us to measure the overall estrogenic activity of cow's milk
in the in vitro yeast reporter bioassay.
First,
we assessed the ability of the bioassay to detect estrogens frequently
detected in milk. The relative potencies of 16 compounds descended in
the order: 17β-estradiol (17β-E2), 17α-ethinylestradiol,
diethylstilbestrol, dienestrol, 17α-E2, estrone, zearalenone, estriol,
equol, genistein, 17β-E2 glucuronide, bisphenol A, apigenin, daidzein.
Flavone, 4-n-nonylphenol and 4-t-octylphenol shown no
activity in the bioassay.The estrogenic activities of milk samples
without hydrolysis were below the detection limit, whereas in 50% of the
deconjugated samples they varied between 0.29 and 0.49 ng EEQ mL−1.
We also compared the estrogenic activity in raw cow's milk collected
from rural and industrial locations in Poland. In our pilot study we did
not observe statistically significant difference in estrogenic
activities in milk collected from the two locations. We found that the
daily intake of estrogens with milk may be higher than estrogen levels
in human serum. Further studies are warranted to evaluate the
significance of milk and dairy as a source of estrogens for humans.
Graphical abstract
Keywords
- Cow's milk;
- Estrogenic activity;
- In vitro bioassay;
- Yeast
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