Soy Hormones & Male Infertility

Soy Hormones & Male Infertility
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The phytoestrogens in soy appear to protect against cancer, but might they reduce male fertility?

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What about soybeans, though? The phytoestrogens in soy protect against cancer—both men and women—but might they decrease male fertility? Fox News thinks so, and they’re “Fair and Balanced.”

Fact, or fiction? Fiction, and it’s interesting why. The study did find that soy decreased sperm concentration, but did not significantly affect the sperm count itself. How can you have the same number of sperm, but a lower concentration? Because of a larger ejaculate volume. Soy appears to stimulate the prostate gland to produce a larger load of ejaculate fluid, but the actual number of sperm remains the same.

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 veganmontreal.

Please consider volunteering to help out on the site.

Image thanks to brownpau via Flickr.

What about soybeans, though? The phytoestrogens in soy protect against cancer—both men and women—but might they decrease male fertility? Fox News thinks so, and they’re “Fair and Balanced.”

Fact, or fiction? Fiction, and it’s interesting why. The study did find that soy decreased sperm concentration, but did not significantly affect the sperm count itself. How can you have the same number of sperm, but a lower concentration? Because of a larger ejaculate volume. Soy appears to stimulate the prostate gland to produce a larger load of ejaculate fluid, but the actual number of sperm remains the same.

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 veganmontreal.

Please consider volunteering to help out on the site.

Image thanks to brownpau via Flickr.

Doctor's Note

Also check out this video on prostate health and plant-based diets: Prostate vs. Plants.

If you haven’t yet, you can subscribe to my videos for free by clicking here.

32 responses to “Soy Hormones & Male Infertility

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        1. That isn’t a study so much as it is a more heavily examined anecdotal case of a single individual. Anecdotes can lead to interesting factors got be investigated in later studies but do not definitively prove anything.

          HOWEVER, its pretty obvious what the issue is here in this specific case- the paper says up front that the patient was eating large amounts of soy, some of it was in the form of junk food (crisps) which doesn’t help. The way they make it sound its as if he was practically eating nothing but soy based products which isn’t the way to be eating anything. Apparently he was eating an upwards of 300 mg of isoflavones a day? A single serving of tofu only contains 22.70 mg

          http://www.isoflavones.info/isoflavones-content.php

          Soy has a protective effect when consumed because the phytoestrogens not only bind to different estrogen receptors than the ones that are linked to cancers, but also they are weaker than the actual estrogens that the body produces. That protective effect is negated if you eat enough phytoestrogens to basically make up for its ‘weaker effect’.

          Greger himself suggests not to eat more than 3-5 servings daily
          http://nutritionfacts.org/video/how-much-soy-is-too-much/

          stick to 1-3 servings a day and you’re fine.

    1. Excellent question! Soy does indeed have so-called “goitrogenic” compounds (as does broccoli-family vegetables and flax seeds), which can interfere with thyroid function in people with marginal iodine intake. The answer is not to avoid these super healthy foods but to just make sure you get enough iodine. See my video Avoiding Iodine Deficiency.

  1. Dear Michael!

    I love this website and want to congratulate you on the amazing work you do!

    Quick comment – the paper by Chavarro states that there was lower sperm concentration among men who consumed soy, but that the ejaculate volume was the SAME. The paper suggests that those eating soy had lower sperm counts.

    The abstract of the article that you referenced suggests that there was no effect on ejaculate volume. Also, in the video, the table you show does suggest a trend of decreasing sperm counts. I wonder if it is clinically relevant though?

    Cheers and Thanks!

    1. If you look at table II (I love open access articles! :) you can see although they find an significant difference in sperm concentration (middle column down at the bottom), since there’s a trend towards larger ejaculate volume (second column down at the bottom) you can see that the statistically significant correlation between soy and sperm vanishes (P for trend = 0.65; bottom of first column in table). Thanks so much for leaving a comment!

  2. Hi Dr. Greger,

    I have a question along this topic.  Can you summarize any available information on how plant-based diets may affect one’s libido?  Does libido generally increase, decrease, or stay the same on a plant-based diet and do certain foods swing it either way?  Thanks for all the great info here and keep up the good work!

  3. please, (Q. 1)does soy milk or soy products consumption significantly reduces the chances of a wife becoming pregnant? or should a woman expecting to become pregnant avoid soy milk / soy products?
    (Q.2) Does intake of soy milk or its products reduces sperm count?

    1. If anything, it would increase the risk of her getting pregnant due to the higher solider survival via to higher ejaculate fluid for protection.

  4. Please, are there some food / processed food that can promote miscarriage during pregnancy that one has to avoid? If yes please kindly list them. thanks.

  5. Afinal! a soja pode ou não causar algum tipo de dano na fertilidade masculina? Ou ainda pode elevar os níveis de estogênio em homens?

  6. Hi Dr. Greger. A friend of mine recently turned down edamame at a dinner outing because she’s trying to get pregnant. You have several videos on your site about male fertility and diet but none about female fertility (that I could find). What is the effect of soy on female fertility? How does it compare to the effect of dairy? Thanks!

  7. Hi there,

    Thank you for this interesting video. Do you have any information on if flaxseeds and there level of Phytoestrogens (18x times higher than tofu) has a negative hormonal effect on men?

    Level of phytoestrogens:
    ¼ cup flaxseeds = 163,133.6 µg

    ¼ cup tofu = 8,688.0 µg

    1. Hi there Sander, I am a volunteer for Dr. Greger. There is currently no evidence (that I am aware of) suggesting that flaxseeds provide levels of phytoestrogens that would have negative impacts on men (or women). In fact, flaxseeds have been shown to prevent prostate cancer in men, along with other benefits. I encourage you to search “flax” in the search bar on NutritionFacts.org. There are quite a few videos regarding the benefits of flaxseeds, with no known drawbacks to date. Here’s just one of the videos, which is on flaxseeds and prostate cancer:

      http://nutritionfacts.org/video/flaxseed-vs-prostate-cancer/

    1. groovy: Here are some other ideas to try: oat milk, hemp milk, rice milk. You might try various brands and also pay attention to whether sweetener is added if that is a concern of yours. You can get milk alternatives that are unsweetened.

    2. Hi, groovy. I am Christine, a NF volunteer moderator. The study you linked is a single case study in which someone consuming large amounts of soy showed these effects. That does not necessarily mean they would occur with any amount of soy in the diet. I think that reasonable amounts of soymilk are probably safe. However, if you are still concerned about soy for your son, you might try a new product available at most Target stores called Ripple Dairy-Free milk. It is made from peas, and is more nutritious than some other plant-based milks. Hemp milk might also be an option, if your daughter tolerates it. I hope that helps!

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