Cows milk decreases testosterone

Finally someone did a study measuring the effects of animal milk on humans & it seems milk does suppress testosterone. Useful the next time someone mentions soya to you.

Here's the abstract

Quote :

http://onlinelibrary.wiley.com/doi/10.1111/j.1442-200X.2009.02890.x/abstract

Keywords:

cow milk;
estrogen;
prepubertal child;
sexual maturation;
sexual precosity

Abstract

Background:  Modern genetically improved dairy cows continue to lactate throughout almost the entire pregnancy. Therefore, recent commercial cow's milk contains large amounts of estrogens and progesterone. With regard to the exposure of prepubertal children to exogenous estrogens, the authors are particularly concerned about commercial milk produced from pregnant cows. The purpose of the present study was therefore to examine concentrations of serum and urine sex hormones after the intake of cow milk.

Methods:  Subjects were seven men, six prepubertal children, and five women. The men and children drank 600 mL/m2 of cow milk. Urine samples were collected 1 h before the milk intake and four times every hour after intake. In men the serum samples were obtained before and 15, 30, 45, 60, 90 and 120 min after milk intake. Women drank 500 mL of cow's milk every night for 21 days beginning on the first day of the second menstruation. In three successive menstrual cycles, the day of ovulation was examined using an ovulation checker.

Results:  After the intake of cow milk, serum estrone (E1) and progesterone concentrations significantly increased, and serum luteinizing hormone, follicle-stimulating hormone and testosterone significantly decreased in men. Urine concentrations of E1, estradiol, estriol and pregnanediol significantly increased in all adults and children. In four out of five women, ovulation occurred during the milk intake, and the timing of ovulation was similar among the three menstrual cycles.

Conclusions:  The present data on men and children indicate that estrogens in milk were absorbed, and gonadotropin secretion was suppressed, followed by a decrease in testosterone secretion. Sexual maturation of prepubertal children could be affected by the ordinary intake of cow milk.

Tiny sample but still a big deal. Worth getting the paper later.

All animal milk contains some hormones. Like the occurrence of witches milk/ neonatal milk. It probably helps babies put on weight so fast, so definitely not good for people wanting to lose fat.

http://en.wikipedia.org/wiki/Galactorrhea

lol at the term "genetically improved"

When exogenous hormones are introduced to the body, they are going to trigger negative feedback to achieve homeostasis. This effect is observed when one takes steroid injections, as well.

But here's some food for thought - steroids are fat-soluble, so reduced-fat dairy has lower concentrations of estrone and 17ß-estradiol. I wonder what variety was used in the above study? A nitty-gritty calculation reveals that pomegranate seeds have over 5,800-fold more estrone per unit of mass compared to skim milk (.017mg/g of seeds).

Quote :

Abstract

Some individuals fear that estrogens in dairy products may stimulate growth of estrogen-sensitive cancers in humans. The presence of estrone (E(1)) and 17beta-estradiol (E(2)) in raw whole cow's milk has been demonstrated. The objectives of this study were to determine if pasteurization-homogenization affects E(2) concentration in milk and to quantify E(1) and E(2) concentrations in commercially available dairy products. The effects of pasteurization-homogenization were tested by collecting fresh raw milk, followed by pasteurization and homogenization at 1 of 2 homogenization pressures. All treated milks were tested for milk fat globule size, percentages of milk fat and solids, and E(2) concentrations. Estrone and E(2) were quantified from organic or conventional skim, 1%, 2%, and whole milks, as well as half-and-half, cream, and butter samples. Estrone and E(2) were quantified by RIA after organic solvent extractions and chromatography. Pasteurization-homogenization reduced fat globule size, but did not significantly affect E(2), milk fat, or milk solids concentrations. Estrone concentrations averaged 2.9, 4.2, 5.7, 7.9, 20.4, 54.1 pg/mL, and 118.9 pg/g in skim, 1%, 2%, and whole milks, half-and-half, cream, and butter samples, respectively. 17Beta-estradiol concentrations averaged 0.4, 0.6, 0.9, 1.1, 1.9, 6.0 pg/mL, and 15.8 pg/g in skim, 1%, 2%, whole milks, half-and-half, cream, and butter samples, respectively. The amount of fat in milk significantly affected E(1) and E(2) concentrations in milk. Organic and conventional dairy products did not have substantially different concentrations of E(1) and E(2). Compared with information cited in the literature, concentrations of E(1) and E(2) in bovine milk are small relative to endogenous production rates of E(1) and E(2) in humans.
2010 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

http://www.ncbi.nlm.nih.gov/pubmed/20494161

Umm, or maybe not (don't you love science):

Quote :

Our results suggested that there were no steroid estrogens including estrone, estradiol and testosterone in pomegranate seed, fruit juice and preparations. Consequently, we assumed that the previously reported analysts of pomegranate were misunderstood their analytical results according to either the estrogen-like effects or similarity of peak retention time and Rf values in experiments.

click here for abstract

I'd suggest it's unlikely that any plant has fabricated any male or female hormone, why would they, it would appear on the surface an unlikely idea. There being similar type compounds seems a much more likely answer (rather like the phytoestrogens found in many plants that are similar, but not identical to chemicals used in mammals). That's not saying these similar products cannot cause issues (either activating or blocking receptors), but they are not likely to be identical products as plants & animals are too dissimilar to need identical hormone systems.

As you said though fat is a major carrier of hormones & actually a major aid in their creation within the body as well, but the best people to test out exactly how much is in milk probably aren't the American Dairy Science Association - umm, can anyone say biased

EDIT [update]:

umm (again)... or maybe yes (clickable link to another study)
From the above link:

Quote :

Results and Discussion
Confirmation of estrone detected from pomegranate extracts

So, it seems controversial whether there is any estrone in pomegranates, but it would seem from all the studies that maybe I'm wrong (wouldn't be the first time) & you can get actual nature identical hormones from plants at least it looks that way from these studies?