Hormones are chemical messengers that travel throughout your dog’s body coordinating complex processes and development of all the systems in your dog’s body. From before birth through the entirety of your dog's life, hormones guide the development of the brain, reproductive and immune systems, and overall growth.
Reproductive organs produce the hormones testosterone and estrogen. It is these hormones that determine masculinity vs femininity, muscle mass, size, and orchestrate sperm production, ovulation, and pregnancy success.
Hormones are secreted directly into the blood by the glands that produce and store them. They float through the bloodstream freely, until they come in contact with their specific receptor. This is why Hormone concentrations are so important. They dictate how often a hormone comes in contact with a specific receptor. Any reduction in your dog’s natural hormones binding to the receptors, can drastically affect your dog’s development and reproductive success, not to mention that numerous studies show that these negative effects can compound over time and even generations.
Chemicals that interfere with the function of hormones are
known as endocrine disruptors. Endocrine disruptors are
able to bind in place of natural hormones causing the body
to react as though natural hormone levels are out of balance.
A major endocrine disrupter is called phytoestrogen, and can
be found in high concentrations in the food we feed our dogs
every day. They block the action of your dog’s hormones, by
keeping it from binding to its receptor. This hormone blocking
causes there to be a detrimental imbalance, because natural
hormones are being blocked from binding the body is receiving
less signals from the right hormones and so development and
health are hindered even though a blood test may show perfect hormone balance in the bloodstream. These disrupters effects also build up over time, even over generations. As they build up their impact is greater, because they are more often impeding your dog’s hormones and changing their internal biology. This results in lower sperm counts, smaller litter sizes, and most importantly dogs that were kept from reaching their full potential.
Are phytoestrogens in my dog food, what ingredients contain it in high amounts?
Phytoestrogen is in all plant-based foods, the idea is eliminating foods high in phytoestrogen. Below is a table with some of the worse culprits in dog food compared to some of the better ingredients.
- Flaxseed (379,380 )
- Soy (103,920)
- Canola oil (8,923)
- Sweet potatoes (8,688
- Chickpeas (3,770)
- Brown rice (4.6)
- Chicken (4.1)
- White Rice (1.4)
You probably heard the uproar about Soy in dog food and the call for its removal. This was due to its estrogen content. Yet the majority of dog foods still have flaxseed, which is over 3 times worse as an ingredient. In fact, you will see a combination of many bad foods in almost every dog food on the market.
Effects on Reproduction
Women consuming a fertility diet were shown to increase their fertility by over 80 percent, according to a paper published in the November 1, 2007, issue of Obstetrics & Gynecology. The study was led by researchers at the Harvard School of Public Health (HSPH) and did not even examine the risk associated with other kinds of infertility, such as low sperm count in men. (9) Another study followed over 17,000 women and showed that a fertility diet and proper exercise had a 69% lower risk of ovulatory disorder infertility (7) A study on mice where doses phytoestrogen were given to female rats showed actual morphological changes to their ovaries and showed reduced fertility, and in the highest doses even infertility. (8) Cows and ewes fed estrogenic forage may suffer impaired ovarian function, often accompanied by reduced conception rates and increased embryonic loss. Eating a fertility diet to boost fertility is one of the most powerful health changes you can make. Numerous studies have shown that specific changes to the diet can improve fertility, prevent recurrent miscarriage and support a healthy pregnancy.
Sperm count is also affected. In a study(1) men were fed varying degrees of phytoestrogen filled foods, in the highest category of phytoestrogen intake had 41 million sperm/ml less than men who did not consume a high phytoestrogen diet. Another study (2) was done in which they wanted to examine the influence of dietary soy and phytoestrogens on testicular and reproductive functions.One set of mice were fed a high phytoestrogen diet from conception to adulthood, another group was fed a low phytoestrogen diet. Both grew up to be fertile, but the male mice fed a high phytoestrogen diet had a 25% reduction in sperm count, and a 21% reduction in litter size. We must also keep in mind that that reduction in litter size is when bred to female rats with a low phytoestrogen diet. Imagine the effect it would have if both were on a high phytoestrogen diet. In a separate study (6) adult rats were fed a high phytoestrogen diet for only 24 days and it significantly decreased their sperm counts from just 24 days earlier.
Phytoestrogen even has its effects at birth weight. It was shown that pregnant rats fed a diet rich in phytoestrogen had lowered birth weights. Phytoestrogens were also transferred to the offspring through the milk.
No matter how we look at it, high doses of phytoestrogens are bad news for the reproductive health of our animals. (4) One study even proposed that phytoestrogens are a phytochemical defense that plants have against animals that consume them.
As I studied these I could see a definite parallel to what I was experiencing and I knew something had to be done. Anything that could be harming our litter sizes and the health of the puppies was inexcusable in my mind.
Effects on Development and Health
Phytoestrogens also disrupt all hormone function which essentially can have its effects on complex processes like growth, metabolism, and can influence the function of the immune system, and even alter behavior. There have been studies suggesting possible links to Neurological issues and certain types of cancers. In fact, phytoestrogens have been shown not to only influence sex hormones and biological activity but also intracellular enzymes, protein synthesis, growth factor action, and malignant cell growth. They also have been shown to cause adverse effects on the development and function of the male and female reproductive system.
Any effect on the reproductive tract compounds the effect phytoestrogens were already having by just disrupting the resting hormone levels. Growth and development are strongly controlled by these hormones. This coupled with phytoestrogen effect on growth hormone itself could have a detrimental impact on your dog's potential, in a sense, we are potentially
stunting our dog's ability to reach their true potential. It was
shown (3) that pregnant rats fed a diet rich in phytoestrogen,
produced rats with lower adult weights, and delayed puberty.
Are our dogs lesser than they should be, are they less
muscular, are they not reaching their full potential, are they
less healthy? The answer to these question is more than likely
yes. With all the time and money we put into our dogs to try
and give our dogs the best nutrition and life possible, trying
to better our breed and sport, the thought of stunting the
progress of our breeding programs and dogs is nothing short
Are the Effects Reversible?
The good news is, is that most of the effect are reversible or somewhat reversible. Reversing its effects is accomplished by switching to a low phytoestrogen diet. It is a somewhat gradual process but before long these endocrine disruptors begin to dissipate from the bloodstream. (8) In the study in which Cows and ewes were fed phytoestrogenic forage. It resulted in impaired ovarian function, often accompanied by reduced conception rates and increased embryonic loss. The infertility seemed to be temporary, it seemed to resolve itself within 1 mo after removal from the phytoestrogenic feed. However, some ewes exposed to estrogen for prolonged periods may suffer a second form of infertility that is permanent, caused by developmental actions of estrogen during adult life. Only the developmental effects are left and there may even be some hope for improvement there, and a lot of promise for the next generation.
(1)Soy food and isoflavone intake in relation to semen quality parameters among men from an infertility clinic Jorge E. Chavarro1,2,7, Thomas L. Toth3, Sonita M. Sadio4 and Russ Hauser3,5,6
(2)Potential detrimental effects of a phytoestrogen-rich diet on male fertility in mice Christopher R. Cederrotha, Celine Zimmermanna, Jean-Louis Benyb, Olivier Schaadc, Chantal Combepinea, Patrick Descombesc, Daniel R. Doergee, François P. Pralongd, Jean-Dominique Vassallia, Serge Nefa, ,
(3)Flaxseed and Its Lignan Precursor, Secoisolariciresinol Diglycoside, Affect Pregnancy Outcome and Reproductive Development in Rats1,2,3 Janet C. L. Tou, Jianmin Chen, and Lilian U. Thompson4
(4)Phytochemical mimicry of reproductive hormones and modulation of herbivore fertility by phytoestrogens. C L Hughes, Jr
(5)Soybean phytoestrogen intake and cancer risk Herman, C; Adlercreutz, T; Goldin, Barry R; Gorbach, Sherwood L; et al. The Journal of Nutrition125.3 (Mar 1995): 757S-770S.
(6)Adult-only exposure of male rats to a diet of high phytoestrogen content increases apoptosis of meiotic and post-meiotic germ cells Stephen Assinder, Ryan Davis, Mark Fenwick and Amy Glover
(7)Disruption of the female reproductive system by the phytoestrogen genistein Wendy N. Jefferson, ,Elizabeth Padilla-Banks, Retha R. Newbold
(8)Detection of the effects of phytoestrogens on sheep and cattle. N R Adams
(9)Diet and Lifestyle in the Prevention of Ovulatory Disorder Infertility Chavarro, Jorge E. MD, ScD1,2; Rich-Edwards, Janet W. MPH, ScD2,3,4; Rosner, Bernard A. PhD2,5; Willett, Walter C. MD, DrPH1,2,4