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Chicken Consumption and the Feminization of Male Genitalia

Eating chicken during pregnancy may affect the size and development of one’s son’s penis due to phthalate contamination of the meat.

September 15, 2011 |
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Supplementary Info

Sources Cited

Colacino JA, Harris TR, Schecter A. Dietary intake is associated with phthalate body burden in a nationally representative sample. Environ Health Perspect. 2010 Jul;118(7):998-1003. Epub 2010 Apr 14.

Swan SH, Main KM, Liu F, Stewart SL, Kruse RL, Calafat AM, Mao CS, Redmon JB, Ternand CL, Sullivan S, Teague JL; Study for Future Families Research Team. Decrease in anogenital distance among male infants with prenatal phthalate exposure. Environ Health Perspect. 2005 Aug;113(8):1056-61.

Harcourt AH, Gardiner J. Sexual selection and genital anatomy of male primates. Proc Biol Sci. 1994 Jan 22;255(1342):47-53.

Stulhofer A. How (un)important is penis size for women with heterosexual experience? Arch Sex Behav. 2006 Feb;35(1):5-6.

Swan SH, Liu F, Hines M, Kruse RL, Wang C, Redmon JB, Sparks A, Weiss B. Prenatal phthalate exposure and reduced masculine play in boys. Int J Androl. 2010 Apr;33(2):259-69.

Swan SH. Environmental phthalate exposure in relation to reproductive outcomes and other health endpoints in humans. Environ Res. 2008 Oct;108(2):177-84.

Meeker JD, Calafat AM, Hauser R. Urinary metabolites of di(2-ethylhexyl) phthalate are associated with decreased steroid hormone levels in adult men. J Androl. 2009 May-Jun;30(3):287-97.

Cho SC, Bhang SY, Hong YC, Shin MS, Kim BN, Kim JW, Yoo HJ, Cho IH, Kim HW. Relationship between environmental phthalate exposure and the intelligence of school-age children. Environ Health Perspect. 2010 Jul;118(7):1027-32.

Meeker JD, Calafat AM, Hauser R. Di(2-ethylhexyl) phthalate metabolites may alter thyroid hormone levels in men. Environ Health Perspect. 2007 Jul;115(7):1029-34.

Stahlhut RW, van Wijngaarden E, Dye TD, Cook S, Swan SH. Concentrations of urinary phthalate metabolites are associated with increased waist circumference and insulin resistance in adult U.S. males. Environ Health Perspect. 2007 Jun;115(6):876-82.

Wood DL, Bitman J. The effect of feeding Di-(2-ethylhexyl) phthalate (DEHP) on the lipid metabolism of laying hens. Lipids. 1980 Mar;15(3):151-6.

MAFF. Phthalates in food. Food surveillance information sheet no. 82; 1996. London, UK: MAFF.

Hauser R, Meeker JD, Singh NP, Silva MJ, Ryan L, Duty S, Calafat AM. DNA damage in human sperm is related to urinary levels of phthalate monoester and oxidative metabolites. Hum Reprod. 2007 Mar;22(3):688-95.

Adibi JJ, Hauser R, Williams PL, Whyatt RM, Calafat AM, Nelson H, Herrick R, Swan SH. Maternal urinary metabolites of Di-(2-Ethylhexyl) phthalate in relation to the timing of labor in a US multicenter pregnancy cohort study. Am J Epidemiol. 2009 Apr 15;169(8):1015-24

Durmaz E, Ozmert EN, Erkekoglu P, Giray B, Derman O, Hincal F, Yurdakök K. Plasma phthalate levels in pubertal gynecomastia. Pediatrics. 2010 Jan;125(1):e122-9.

Mendiola J, Stahlhut RW, Jørgensen N, Liu F, Swan SH. Shorter anogenital distance predicts poorer semen quality in young men in Rochester, New York. Environ Health Perspect. 2011 Jul;119(7):958-63.

Kim BN, Cho SC, Kim Y, Shin MS, Yoo HJ, Kim JW, Yang YH, Kim HW, Bhang SY, Hong YC. Phthalates exposure and attention-deficit/hyperactivity disorder in school-age children. Biol Psychiatry. 2009 Nov 15;66(10):958-63.


Images thanks to aleksas, baalands, Ariusz and Renee Comet at the National Cancer Institute. And a very special thanks to Stephen Walsh (author of the fabulous Plant Based Nutrition and Health), for his time, effort, and patience working with me to improve this video and associated blog.


 Sexual selection may have also played a role in penis size.  According to the best available science, three quarters of women find  both penile length and girth,  somewhat or very important.

What does this have to do with diet?

 Pthalates.

“Phthalates are [chemical] compounds that are used in a wide range of consumer products, [including pesticides, paints, and PVC plastic]. However, the contribution of dietary intake to phthalate exposure has not been well defined.”

What the problem with phthalate exposure?  "Effects on sexual health and development have been observed in recent human studies."

We’ve known phthalates affect the genital development of lab rats, but for the first time ever,  human data has been published.

Simple study. They measured the levels of phlatates flowing through the bodies of pregnant women, and then later measured the size and characteristics of their infant sons genitals after birth between ages 2 months to 3 years. The women who had the most exposure had up to  10 times the odds of giving birth to sons with one or both testicles incompletely descended, their scrotum categorized as small and/or “not distinct from surrounding tissue,” and a significantly smaller penis volume, a measure of penis size taking into account both length and girth.

In  other words, the more phthalates pregnant women are exposed to, the increased likelihood of testicular maldescent, a small and indistinct scrotum, and smaller penis size.”

 They conclude: “These changes in male infants, associated with prenatal exposure to some of the same phthalate metabolites that cause similar alterations in male rodents, suggest that commonly used phthalates may undervirilize humans as well as rodents.”

So  what foods should pregnant women stay away from to avoid the phthalate-related syndrome of incomplete virilization?

 The urine levels of thousands of Americans all across the country were measured, along with their diets, to find out food most significantly correlated the phthalate exposure within the body.

 They looked at dairy,  eggs,  fish,  fruit,  poultry,  potatoes,  tomatoes,  vegetables in general,  and red meat. Statistically, the most significant result in their analysis was  poultry consumption.

 So for example, “In one analysis, while  total dairy consumption was significantly associated with one of the phthalate chemicals, called MCPP,  and eggs with another,  poultry consumption was a significant predictor of levels of all of the individual DEHP metabolites, MEHP, MEHHP, MEOHP, MECCP, etc., etc.,  etc..

 “suggesting… that an increase of one ounce of poultry per day is associated with an increase in one of the pthalate metabolite levels of approximately 5.7%. A single chicken breast is nearly 8 ounces.

Maybe it was just leaching into the meat from the plastic wrap packaging?  Probably not. “the finding that egg consumption is significantly associated with levels of phthalates too, suggests that chickens themselves may be contaminated and that food is not being contaminated just through packaging and processing.

So if there is one thing pregnant women may want to avoid during pregnancy to protect their son’s normal development it would be to avoid poultry.

To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring watch the above video. This is just an approximation of the audio contributed by Dianne Moore.

To help out on the site please email

Dr. Michael Greger

Doctor's Note

Please feel free to post any ask-the-doctor type questions here in the comments section and I’d be happy to try to answer them. Also, there are 1,449 subjects covered in my other videos–please feel free to explore them!

For some context, please check out my associated blog posts: the first monthEating chicken may lead to a smaller penis, Pollutants in Californian Breast Tissue, and Heading Shrinking from Grilling Meat

  • Michael Greger M.D.

    Please feel free to post any ask-the-doctor type questions here in the comments section and I’d be happy to try to answer them. Be sure to check out the corresponding blog post Eating chicken may lead to a smaller penis as well. Also, there are 1,449 subjects covered in my other videos–please feel free to explore them!

  • Jennifer Eldred

    What about DEP that go in fragrances are there any human studies for that?

    • Michael Greger M.D.

      Such a great question Jennifer! Before we knew that there were any of these industrial pollutants in the food supply, the levels in cosmetic and personal care products were in fact the number one concern. The most recent review on the subject that is available full-text online is “Toxic effects of the easily avoidable phthalates and parabens.”

  • Pat Saunders

    Michael, do you know if these statistics would also be relevant for Australia?

  • Eric Needs

    Great, all my mom ate when she was pregnant was chicken. NOW look at this thing! (jokes)

  • klickityklack

    Very interesting research. In light of some other (conflicting) studies that show phytoestrogens also impact genital development — in your view, what protein choices are best for expectant moms?

    Also, do we have any data from the Food Science world measuring the levels of phthalates in organic vs. conventionally produced meat/animal-based foods?

    • Toxins

      Hello klickityklack! I believe I can assist you with your question!

      Regarding the comment on phytoestrogens, phytoestrogens actually do not affect male estrogen levels. Dairy actually increased levels significantly. Check out Dr. G’s video on that here:

      Regarding the protein question, it is of no concern to focus on eating protein if you eat a whole foods plant based diet. All plants are complete proteins. The American Dietetic Association acknowledges this fact and states that “Plant protein can meet protein requirements when a variety of plant foods is consumed and energy needs are met. Research indicates that an assortment of plant foods eaten over the course of a day can provide all essential amino acids and ensure adequate nitrogen retention and use in healthy adults; thus, complementary proteins do not need to be consumed at the same meal” Basically, if you eat when your hungry and till your full then your getting enough protein for you and your baby since your body will be hungry when you need more energy. You also don’t need to compliment different foods since each plant source is a complete protein in itself. The world Health Organization also claims that we do not need too much protein. About 0.45 grams of protein per kilo of body weight. This is a moderate level and doesnt come out too much. Dr. McDougall also states that protein is also used in small quantities every day so we really do not need to focus on getting it specifically. As stated before, eat a balanced whole foods plant based diet, eat till your full and when your hungry and you will be well off. Spinach is 51% protein whereas beef is 37% protein!

      Regarding the difference between conventional and organic products, As Dr. T. Colin Campbell puts it, the differences between organic and conventional meat in compositional makeup is insignificant. It is still the same lack of phytochemicals and antioxidants and the same type of nutrients and protein. Organic is more of just a label on meat on a health standpoint.

      Hope this helped!

  • amcken3

    What I’m wondering is how these companies get away with this. Arsenic is a POISON, they finish off the chickens with ARSENIC. They should be prosecuted for attempted murder. That would set a strong message. WHY ARE WE TOLERATING THIS!?

  • robert

    hey doc. can the phthalates, dehp etc, be detox out of the body and by nutrients, supliments etc. thanks.

    • Don Forrester MD

      Your body will clear these substances naturally so the best way to detox is to avoid intake and let your bodies normal mechanisms via the liver and kidneys do their jobs. The good news is phthalates clear relatively quickly as opposed to dioxins whose half lives are estimated to be 1-7 years see…

  • Victoria Alice Westwood

    Dr Greger – I would love to hear your opinion on the latest craze in the fitness industry namely ‘Intermittent Fasting’. Proponents claim that it not only sheds excess fat from the body in a short amount of time, but also has many other benefits including better glycaemic control, reduced levels of IGF-I and reduced oxidative stress. I thought these were all benefits of a plant-based diet! Are there any benefits to IF that extend beyond a vegan diet? Are there any potential harmful effects? Many thanks, Dr Westwood, UK.

  • Tatiana

    Dear Dr. Greger,

    My 24 year old son was diagnosed with testicular cancer this year. I follow you and your studies closely and am wondering if you ran across any correlations or observations in reference to this rare cancer. I would appreciate any input including any dietary suggestions. We follow a high vegetable/fruit diet and he eats meat, eggs occasionally. He is allergic to dairy.
    Truly appreciate your time and website! Tatiana

    • Don Forrester MD

      I have seen no studies relating to any of the types of testicular cancer. In general whole food plant based diets are associated with less cancer for a variety of reasons. I would tend to avoid meat, dairy, eggs and fish. You might benefit from resources on the website from The Cancer project see You may be able to find a Food for Life instructor in your area who is giving a series of cooking classes. The other advantage to eating whole food plant based diet is avoiding other chronic diseases. Good luck.

  • Paul Webster

    People have been eating chickens for many years and there has not been a problem so I would think it must be something in the new food, drugs, etc.

  • Carlee

    Does this data also apply to organic chicken and eggs? This information in your video would be helpful.

  • shazad

    HI this is shazad i want to ask a tips about penius enlargment my penius is so small upto 3.5 inch and my age is 23 year and i m very worry about it.I cannot afford any expensive supplements so plz suggest me sir what should i do i should gain my proper size.
    plz send your answer at my

  • Sebastian Tristan

    O.K. Now, it’s personal!

  • Esquimal

    Very interesting thanks. Would you think is safe to eat organic eggs and organic chicken/turkey during pregnancy and breast feeding?

    Many thanks

    • Don Forrester MD

      I would avoid both eggs and chicken and turkey not only during pregnancy but also before and after pregnancy. My daughter went through both her pregnancies following a whole food plant based diet and was easily able to meet her protein and nutritional needs. Of course you need to work with your physicians. A good resource for information so you can work effectively with your physicians is… Reed Mangels, The Everything Vegan Pregnancy which also covers infants (note PCRM also has free booklet Nutrition for Kids available for free download). She also has free resources online at or Another resource is Good luck and keep tuned to as the science keeps coming.

  • limmy

    Hi talking about shrinking of penis of boy , what about middle age men thanks