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Is Soy Bad for You? Examining Both Sides of the Argument


When I first decided to stop drinking cow milk, I immediately turned to soy milk. To tell you the truth, I didn't know of any other milks other than cow and soy milk, and the latter was being heavily advertised at that time as the healthiest choice. Eventually, I ran into some unfavorable articles and comments regarding soy milk. I started questioning my decision and ran to Google to learn more about the issue.

The beginning of the soy craze

In 1999, the FDA announced that soy could significantly reduce heart disease if included in your daily diet. From that day on, soy became super popular and we started seeing soy products everywhere, from baby formulas to soy meat. There were claims that soy could replace animal protein and that it could even fix hormonal imbalances. But soy's fate changed, and today more and more people believe using soy can lead to some pretty bad health problems.

Which side of the argument are you on?

Soy: the good and the bad

It's unbelievable how much information there is out there about soy! And when there is such a debate about any issue, you can always count on finding people on both extremes: those who are blindly for it and those who are fanatically against it. I will present to you the most coherent arguments I found on BOTH SIDES, and you will take the decision on whether soy is good or bad for your health.

Soy is everywhere now! Even in products you wouldn't imagine...

Soy is everywhere now! Even in products you wouldn't imagine...

The bad side of soy

The main complaint about soy is its alarmingly high content of phytoestrogens. Phytoestrogens are vegetable components that can act as the feminine hormone known as estrogen. This female hormone is mainly responsible for changing a girl's body into a woman's body. However, it can also be responsible for causing malignant tumors, such as the ones that are present in hormone sensitive breast cancer.

Soy and women

Soy could increase risk of breast cancer due to its high amounts of phytoestrogens. It could also cause problems with the reproductive organs such as increased bleeding during menstruation as well as more painful periods, premature births and difficulty conceiving.

Soy and men

Since phytoestrogens can have similar effects as estrogen, many are concerned with the effect soy could have in men. Some say that the high amount of isoflavones (a type of phytoestrogen) can lead to less testosterone, and thus, decreased libido in men. There have also been claims that soy, when consumed in large quantities, can cause gynecomastia, the abnormal enlargement of mammary glands in men.

Goiter caused by an enlarged thyroid gland.

Goiter caused by an enlarged thyroid gland.


Soy is a goitrogen, which is a fancy word to say that it suppresses the function of the thyroid gland. This can lead to thyroid enlargement and to Goiter (swelling of the neck due to an enlarged thyroid.) Because the thyroid gland stops functioning as well as it should, you could potentially end up with hypothyroidism.

Soy and digestive problems

Soy contains high levels of phytic acid. Phytic acid is not digestibly by humans. The worst thing is that it inhibits the body from properly absorbing essential minerals, such as iron, calcium and zinc, which are essential to the development and functioning of the brain and nervous system.

Protease and trypsin are enzymes that help with the digestion of protein. Soy contains protease and trypsin inhibitors, which means that your body will have a hard time digesting and absorbing protein.

Soy and Cancer

As stated before, soy could increase breast cancer risk, as well as other forms of cancer. Four grams of soy daily could increase risk of prostate cancer by 120% and ovary cancer by 15%.

Soy has made its way even to baby formulas.

Soy has made its way even to baby formulas.

The good news about soy

Now that we heard all the bad stuff about soy, let's hear a bit of good news. The good news pretty much summarize in three parts:

  • In order to cause all those problems, soy has to be consumed in large quantities
  • Most studies that have been done about soy have been done on animals. (Animals don't react the same as humans to everything.)
  • The type of soy you eat matters.

Did you know?

As of 2012, 93% of American soy production was genetically modified. This is the type of soy that can be harmful to your health...

Studies with humans

A study published in 2001 in one of the main magazines of the JAMA (Journal of the American Medical Association) found that babies that were fed with soy were in same or better health that babies that were fed with cow milk (breast milk is still be the best option).

The study also followed 811 men and women between 20-34 years of age. These men and women had previously participated in cow milk vs. soy milk studies in their childhood. The results? They had no difference in their overall health and no reproduction problems when compared to the children who grew up on cow milk.
*There was only one difference: women's cycles were slightly longer (by 8 hours) than those who drank cow milk.

Animal studies

Most of the negative findings about soy have been based on animal studies. The first negative results about soy came from a 1985 study which linked soy to pancreatic cancer in rats. However, before we get scared, we need to know that rats, as well as chickens, have a pancreas that is very sensitive to protease inhibitors found in soy. The rat pancreas is very different from the human pancreas. Different needs, different pancreas.

To put things in perspective, think about this: breast milk is toxic for rats, but that doesn't mean it's also toxic for babies. In fact, as we all know, breast milk is the best thing a baby could drink. Not everything that is bad for animals, is also bad for humans.

Types of soy

Some of the healthiest and long-lived people come from places that consume plenty of soy. However, the soy they consume might be very different from the one we get in more developed countries. Soy could be perfectly healthy as long as it is not GMO (genetically modified) and as long as it hasn't been fumigated with chemical products. So good luck finding soy like that.

Say 'no' to genetically modified soy!

Say 'no' to genetically modified soy!

Everything in moderation

Even the healthiest foods need to be consumed with moderation. The same applies to soy. Since we still don't know exactly what soy can or cannot cause, eat it with moderation. Have a healthy diet, and don't rely too much on one single thing to act as the elixir for all health problems. Eat a healthy and moderate diet.

Happy living!

This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.

© 2014 Silver Q


Silver Q (author) on November 18, 2014:

Well said, paxwill! Thank you for reading and commenting!

paxwill on November 05, 2014:

This is very eye-opening. I'm slightly allergic to soy so I've avoided for a long time for those reasons, not because of the phytoestrogens. As they say, poison is in the dose, if you eat it in moderation you should be okay.

Silver Q (author) on March 06, 2014:

Hi marshacanada:

I know, I'm still waiting for that moment, too. Thank you for reading and commenting!

marshacanada from Vancouver BC on March 05, 2014:

Hopefully soon GMO food products will have to be labeled as such.

Silver Q (author) on March 04, 2014:

Hi marshacanada:

Yes, not many studies have been done on humans regarding the consumption of soy, and it seems like all the studies that show negative results have been conducted on animals. I'm glad soy has worked so well for you and your mother. Thank you for reading and commenting!

Silver Q (author) on March 04, 2014:

Hi Vanderleelie:

You are completely right about the GMO products, and it's really scary! I guess we can't really hide from these sort of things so moderation is always the best way to go. Thank you for commenting and reading!

marshacanada from Vancouver BC on March 01, 2014:

I am very healthy and I've been eating soya in the form of tofu for over 50 years. I am 69 years old and was vegetarian for about 10 years. Then I ate tofu instead of meat. I love tofu and eat it a few times a week now. My mom drinks soy milk daily and she is 95 years old and in very good health. A very dear close relative of ours who never eats any soy products had a bout of cancer.

I have never seen a detailed research on humans linking cancer to tofu. I think it's not really accurate to say that tofu causes cancer in humans.

Vanderleelie on February 28, 2014:

A good hub, offering a balanced view of the health issues surrounding soy. The full effects of GMO foods on humans are not yet known, and it's wise to be cautious. Many countries have banned GMO products, but in North America we are consuming them daily often without restrictions or warnings. Your hub offers good advice - moderation. Voted up and shared.

Silver Q (author) on February 26, 2014:

Hi dejvimanushi:

Thank you for reading and commenting!

Silver Q (author) on February 26, 2014:

Hi DonnaCaprio:

I like the taste of almond milk better, too. I was never really a fan of soy milk, I drank it for a while, but never really enjoyed it. Thank you for commenting and reading!

Donna Caprio Quinlan from Newburyport, MA on February 26, 2014:

I used to drink soy milk and switched to almond milk a few years ago. I heard it is healthier and I like the taste of it better than soy. Good point, in that it is probably the GM soy that is the problem and not the real soy.

Thanks for a good post!

Dejvi Manushi from Albania on February 26, 2014:

Very interesting hub. I enjoyed reading it. Well Done...

Silver Q (author) on February 25, 2014:

Hi Mary McShane:

Thank you for that informative comment. I will update my numbers to reflect what you mentioned. Thank you for reading and commenting!

Mary McShane from Fort Lauderdale, Florida on February 25, 2014:

Hi SilverQ, I don't know if you are in the US or not, but in the US, as of 2012, 93% of the soy grown is GM (genetically modified). The numbers are still not up to date for 2014. I personally don't believe soy is good for people who have no health issues, so anyone with health issues I believe it even more strongly. Here is a link to back up my quote of 93%.


Besides corn and cotton, soy ranks at the top of the list for GM crops.

Figure into the mix that the crops are being fed to animals, which many of us eat, we are getting GM material indirectly. You can get non-GMO foods, but it really comes down to trust. Do you trust that the food has been grown that way when there are so many deceptive labels and people in the world?

While soy is the answer to many who have food allergies, GM soy is not the answer. In fact, it can cause a whole laundry list of more problems, as you have noted in your article.

Getting non-GM foods will become harder and harder as long as the wording is not on the labels and as long as people are untruthful so they can continue to make a buck, however deceptively.

Good info, voted up and shared. :)

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