An in vitro comparison of estrogenic equivalents per serving size of some common foods

Authors: SHAPPELL, NANCY - Retired ARS Employee; BERG, ERIC - North Dakota State University; MAGOLSKI, JAMES - Coleman Natural Foods; Billey, Lloyd

Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/29/2019
Publication Date: 11/19/2019
Citation: Shappell, N.W., Berg, E.P., Magolski, J.D., Billey, L.O. 2019. An in vitro comparison of estrogenic equivalents per serving size of some common foods. Journal of Food Science. https://doi.org/10.1111/1750-3841.14847.
DOI: https://doi.org/10.1111/1750-3841.14847

Interpretive Summary: The estrogenic activity of some common foods was assayed using a cell assay, in order to provide a comparison of their possible potential for estrogenic effects based on “serving size”. Foods included: skim milk, rice, ground beef patties obtained from the muscle and fat of steers raised with or without hormone implantation, and tofu burgers. Values were compared to the activity from one “dose” of the hormone replacement therapy used in post-menopausal women (Premarin ®). The highest estrogenic activity was found in a cooked tofu burger, with > 3 times the activity of Premarin® and more than 8,000 times that of a serving of skim milk. The activity of rice samples were highly variable (0 – 61 times skim milk, possibly due to contamination with the mold zearalenone), but plastic bags provided by the manufacturer for cooking the rice added very little estrogenic activity. Ground beef burgers prepared from tissues collected from cattle that had received estrogenic growth promoting implants (or not) had 2,500 times less activity than tofu burgers. Measured estrogenic activity was similar to predicted activity based on measured chemical concentrations of the most estrogenic components.

Technical Abstract: The public assumes that some foods, such as milk and ground beef from cattle receiving steroidal implants, are associated with estrogenic hormones, while other foods are presumed “safe” or nonestrogenic. Here, we investigate these assumptions by assessing the relative estrogenic activity of a serving size of four foods: skim milk (8 oz), rice (48 g dry wt) in cooking bag, ground beef patties from steers raised with or without hormone implantation (quarter lb each, 114 g), and tofu burgers (isocaloric to beef burger, 198 g), using an in vitro assay (E-Screen). Mean picogram (pg) estradiol equivalents (E2Eqs) on a serving basis were as follows: skim milk 120; rice 400; rice prepared in cooking bag 370; rice boiling bag alone 4 pg per bag, ground beef burger (obtained from the tissue of cattle that had received no hormone implants) 389, beef burger (obtained from cattle that had received hormone implant) 384, and tofu burger 1,020,000. Rice E2Eqs were highly variable, but the plastic cooking bags provided by the manufacturer added negligible E2Eqs. The source of estrogenic activity in rice may have been due to contamination with the mycotoxin zearalenone. The E-Screen E2Eqs of tofu burger extracts agreed with those predicted based on chemical concentrations of the most estrogenic component times their E2Eq factor. While a tofu burger contained around three times the estrogenic activity of a daily dose of estrogen replacement therapy (125 mg, Premarin'', 303,000 pg); the other foods––a quarter pound ground beef burger at approximately equal calorie count, a serving of milk, or rice, were all at least 750-fold less estrogenic.