Written by Marcia J. Egles. In this study off-spring of BPA-exposed rats had an increase in prostate gland abnormalities compared to control rats. BPA- exposed off-spring, whose mothers were fed indole-3 carbinol, had less of these abnormalities, many of which returned to normal within 180 days.

Bisphenol A, otherwise known as “BPA”, is a substance widely used in the production of polycarbonate plastic and epoxy resins found worldwide in many consumer products including food packaging, plasticware, canned food linings, PVC pipe finishing materials, and some dental fillings. Largely because of adverse effects of BPA demonstrated in numerous animal studies, there has been controversial concern about the widespread exposure of humans to BPA (2, 3). In a recent study of pregnant rats exposed to BPA, indole-3-carbinole was shown to reduce the harmful effects of BPA to the developing prostate glands of the offspring (1).

Though the effects of BPA on humans are not yet known, the fact of human exposure to BPA is documented (1, 4). Research conducted by the National Health and Nutritional Examination Survey (NHANES) of the American Center for Disease Control (CDC) from 2003-2004 detected BPA in the urine of 92.6% of a sample of 2500 American adults and children (4).

A form of indole-3-carbinol, glucobrassicin, is the main bioactive compound found in high concentrations in cruciferous vegetables such as broccoli, cauliflower, cabbage and Brussel sprouts. Indole-3-carbinol has been shown in previous rodent studies to have anticarcinogenic and antimutagenic properties against various chemical carcinogens, and may function as an anti-estrogen (5).

BPA is known to cause multiple microscopic changes to the developing prostate tissue of male rats when their mothers are exposed to BPA during pregnancy (1). BPA has been identified as an “endocrine disruptor” with characteristics similar to the hormone estrogen (6).

In the new study, pregnant rats were treated as follows to determine the effects of indole-3 carbinol on BPA exposure:

  • Group 1: Control with regular rat chow and no BPA exposure.
  • Group 2: BPA 25 micrograms per kg body weight* per day from gestational days 10 to 21, regular rat chow.
  • Group 3: Same as Group 2 except with concurrent feeding with 2 grams of indole-3 carbinol per kg rat chow instead of regular rat chow.
  • Group 4: BPA 250 micrograms per kg body weight* per day from gestational days 10 to 21, regular rat chow.
  • Group 5: Same as group 4 except with concurrent feeding with 2 grams of indole-3 carbinol per kg of rat chow instead of regular chow.

All the offspring received regular rat chow and no further BPA exposure after birth. Eight male pups from each group were studied at age 21 days. Eight more from each group were studied at age 180 days.

The BPA-treated groups showed an increase in a variety of complex microscopic abnormalities in their prostate glands as compared with the control rats. The BPA exposed rats whose mothers were fed indole-3 carbinol had a lessening and normalization of many of these changes, most notably at 180 days.

The potential for indole-3 carbinol as a defense against the possible untoward effects of BPA is intriguing. The safety of indole-3-carbinol (which may function as an anti-estrogen) in human pregnancy or lactation has not been established. The consumption of uncontaminated cruciferous vegetables such as broccoli has an excellent longstanding safety record.

*One report estimated the human consumption of BPA to be less than 1mcg/kg body wt./day, and the range is from 0.48-1.6mcg/kg body wt./day according to the European Commission. The study values when converted to human equivalents showed the rat dose of 25mcg/ kg body wt. equals 4.05mcg/ kg body wt. in humans, and 250mcg/ kg body wt. corresponds to 40.5mcg/ kg body wt. Chrystal Moulton, Staff Writer.

Source: Brandt, Joyce Zalotti, et al. “Indole-3-carbinol attenuates the deleterious gestational effects of bisphenol A exposure on the prostate gland of male F1 rats.” Reproductive Toxicology 43 (2014): 56-66.

© 2013 Elsevier Inc. All rights reserved.

Posted March 2, 2015.

References:

  1. Brandt, Joyce Zalotti et al.   Indole-3 carbinol attenuates the deleterious gestational effects of bisphenol A exposure on the prostate gland of male F1 rats, Reproductive Toxicology, 43 (2014) 56-66.
  2. Welshons WV1, Nagel SC, vom Saal FS. Large effects from small exposures. III. Endocrine mechanisms mediating effects of bisphenol A at levels of human exposure. Endocrinology.2006 Jun;147(6 Suppl):S56-69.
  3. Durando M. et al Prenatal bisphenol A exposure induces preneoplastic lesions in the mammary gland in Wistar rats. Environ Health Perspect 2007: 115:80-6.
  4. Calafat AM, Ye X, Wong LY, Reidy JA, Needham LL 2008 Exposure of the U.S. population to bisphenol A and 4-tertiary-octylphenol: 2003–2004. Environ Health Perspect 116:39–44 .
  5. Souli E, Machluf M, Morgenstern A, Sabo E, Yannai S. Indole-3-carbinol (I3C) exhibits inhibitory and preventive effects on prostate tumors in mice. Food Chem Toxicol 2008;46:863–70.
  6. Ruben BS. Bisphenol A: An endocrine disruptor with widespread exposure and multiple effects. J Steroid Biochem Mol Biol 2011: 127:27-34.
  7. Vandenberg LN, et al. Human exposure to bisphenol A (BPA). Reprod Toxicol. 2007 Aug-Sep;24(2):139-77.