Eating chicken during pregnancy may affect the size and development of one's son's penis due to phthalate contamination of the meat.
The top three sources of industrial toxins in the diet are fish oil, fish, and eggs.
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 that have to do with diet?
“Phthalates are [chemical] compounds…used in a wide range of consumer products [including pesticides, paints, PVC plastic]. However, the contribution of dietary intake to phthalate exposure has not been well defined.” Until now.
What’s 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 phthalate flowing through the bodies of pregnant women, and then later measured the size and characteristics of their infant sons’ genitals after birth, between ages two months to three years.
There was one phthalate particularly associated with a smaller penis: mono(2-ethylhexyl) phthalate, MEHP. The researcher concludes: “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…”
So, what foods should pregnant women stay away from to decrease their phthalate exposure in hopes of avoiding 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 which foods most significantly correlated with phthalate body burden.
They looked at dairy, eggs, fish, fruit, poultry, potatoes, tomatoes, vegetables in general, and red meat. The food associated with the greatest exposure to phthalates was poultry consumption.
So, for example, in one analysis, while total dairy consumption was significantly associated with one of the phthalate chemicals, it was the eggs and the poultry consumption, in particular, that was a significant predictor of levels of MEHP, as well as total phthalates.
This is consistent with what’s been found measuring phthalate levels directly in foods. Yes, there’s some in other meat products, fish, fats, oils, and milk, but poultry was the worst, “suggesting…that an increase of one ounce of poultry per day is associated with an increase in DHP metabolite levels of approximately 5.7%.” A single chicken breast can be eight ounces.
And one of those metabolites is MEHP, the phthalate most closely tied to small penis size in infant boys. In fact, that was the most statistically significant finding in the whole study—the correlation between poultry consumption and MEHP. In addition to a smaller penis, MEHP appears to increase the odds of boys later growing breasts, 25-fold, and then decreased testosterone later in life. Now, look, just because you have a smaller penis doesn’t necessarily mean you’re less masculine, as was widely reported.
But there was actually a study published last year showing that the phthalates found in chicken were significantly associated with less masculine behavior in boys, such as playing less with trucks, and more with dolls, for example. The chicken phthalates have also been associated with increased odds of Caesarean section, diminished child intelligence (particularly in boys), attention deficit and hyperactivity disorder (ADHD) symptoms, later in life, abdominal obesity, altered thyroid function, damaged sperm, and, as we learned this summer, a lower sperm count.
Why is chicken so contaminated? Maybe it’s just leaching into the meat from the plastic wrap packaging? Probably not. The finding that egg consumption is significantly associated with levels of the penis-shrinking MEHP suggests that chickens themselves may be contaminated, and that food is not being contaminated just through packaging and processing.
Maybe it’s in the feed? Phthalates have been intentionally fed to chickens in hopes of decreasing the cholesterol levels in their muscles and eggs, but it didn’t work.
Regardless, if there is one thing pregnant women may want to avoid during pregnancy to protect their sons’ 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.
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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.
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.
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.
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
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.
For more on phthalates and other endocrine disruptors, check out these videos:
Alkylphenol Endocrine Disruptors and Allergies
Dietary Sources of Alkylphenol Endocrine Disruptors
Estrogen in Meat, Dairy, and Eggs
Male Fertility and Diet
Preventing Asthma With Fruits and Vegetables
Protein, Puberty, and Pollutants
For more context, also check out my associated blog posts: NutritionFacts.org: the first month; Eating chicken may lead to a smaller penis; Pollutants in Californian Breast Tissue; and Head Shrinking from Grilling Meat.
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