Soy May Lower Sperm Count

A half serving of soy-based foods a day may significantly lower a man’s sperm count, according to new research.

Previous animal studies have linked large amounts of soy isoflavones to infertility. Isoflavones, sometimes called phytoestrogens, are compounds that mimic the effects of estrogen. However, little human research has been performed in this area. This recent study, presented at the 63rd Annual Meeting of the American Society for Reproductive Medicine, is believed to be the largest human trial to examine the relationship between semen quality and isoflavones.

The researchers analyzed the soy intake of 100 men who went to fertility clinics between 2000 and 2006. The men provided semen samples and answered questions about how often they ate soy-rich foods, such as tofu, tempeh, and soy milk, in the last three months.

Because different foods contain different amounts of isoflavones, the researchers set a standard for serving sizes of particular foods. For instance, one serving of soy was equivalent to two cups of soy milk and one soya burger. The subjects were then divided into different groups based on the amount of soy they ate.

On average, the men in the highest intake group ate a half serving of soy per day. These men had an average of 65 million sperm per milliliter of ejaculate, which was about 40 percent less than men who ate no soy foods. A normal sperm count ranges from 80 million to 120 million per milliliter, while 20 million per milliliter or below is considered low.

The association was strongest in overweight men, suggesting that hormones may be involved. This is because overweight men produce higher levels of androgen-produced estrogen than healthy men.

However, it is unclear if soy intake affects aspects of male health, such as fertility. It is possible that other behaviors, besides soy intake, influenced the results because this was an observation trial. Larger studies are needed to determine if soy foods should be avoided in men trying to conceive.

Soy manufacturers caution that these findings contradict earlier studies that found soy has no impact on sperm count.

For more information about soy, please visit Natural Standard’s Foods, Herbs & Supplements database.

Comments

[Ann]

This is very interesting. What is the mechanism of action? There are so many types of soy, such as tofu, soy milk and soy beans. How much does one have to eat to see these effects?

[loli]

It is interesting how one thing can exert so many opposite effects to the body. Soy is known for its hormonal effects on women with menopausal symptoms. However, it is now said to have the completely opposite actions on men. There is actually a new study that I have just read claiming that soy-rich diet along with lifestyle intervention can modulate the gene expression in prostate cancer. I guess we just have to wait for more research before judging the effectiveness of soy. Here is the link to the study if you are interested:

http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=18559852.

[Meg]

Soy has been taking a hard hit lately. It received lots of attention just a few years ago, and now I'm seeing all these reports on how it may not be as good as everyone first thought (although people have been eating soy for hundreds of years in other cultures). I, for one, find that soy doesn't work for me. Other reports have noted that bloating, nausea, diarrhea and migraine headache have occurred. I guess this just goes to show that soy isn't for *everyone.* Ann - I have also read that soy may have estrogen-like effects, which might lead to the reduction in sperm production...

[AJ]

Not only do you have to be cognizant of the foods you eat, but evidently, men should be cautious when biking. It has been noted that bicycling has been linked to male impotence and sperm count reductions due to the pressure from the bike seat, which results in blood vessel and nerve damage. Specifically, mountain biking can result in an increased incidence of lower sperm count in males because of the extreme jolts and vibrations, which makes the scrotum more susceptible to injury.

[mo]

OK, so I guess I’ll cancel my bike tour around soy country. Seriously, this research does raise some interesting questions. Of course, this would depend on whether or not soy actually decreases fertility, but if it does, there may be applications for a male birth control. Perhaps there is a way to manipulate male fertility by providing the active (estrogenic) compound found in soy?

[Meg]

Mo,

You make a good point. Even if this decreased sperm count translates into reduced fertility, that might not be a bad thing for some people. I remember when it came out that Mountain Dew may lower sperm count, many of my guy friends started drinking it regularly - specifically for this reason.

[Roz]

After thinking that soy was the great answer for everything, it appears that is not even nearly true. I learned from one practitioner that when they initially process soybeans (maybe the cleaning process), they use a formula that includes formaldehyde! That is an alarming thought. Formaldehyde is a carcinogen, and if the soybeans are exposed to that early on in their processing, who knows how much is absorbed and retained. Has anyone else heard about this?

[S. Kalish]

It is interesting that the high-intake group in the study ate only half a serving of soy per day, yet showed sperm counts 40 percent less than in the no-soy group. Of course, these men were already going to a fertility clinic, so there may have been a higher percentage with low sperm counts to begin with, and perhaps these men would be more sensitive to the effects of soy than men who weren’t going to clinics. It would be interesting to run a study comparing these groups.

[ATAD]

It is the compound in soy products called geinstein that actually impairs the sperm as it travels towards the egg. Evidently, this compound is present in all soy products (i.e., vegetarian foods, pre-packed pizzas). A UK fertility expert, Professor Lynn Fraser, advised at a fertility conference to avoid soy-containing food around the women’s most fertile days in the month to promote conception.

[lam]

Mo,

That is in fact a great way to look at soy – a cheap and easy birth control. I am sure a lot of guys would fall for it. Like many other contraceptives, soy alone is not absolutely effective (or at least questionably) and should be administered along with other methods to prevent pregnancy.

[AT]

“The results of a 1995 meta-analysis (combining results from separate but related studies) published in the New England Journal of Medicine found that consuming an average of 47 grams of soy protein a day, rather than animal protein, significantly decreased LDL cholesterol in people with moderately elevated or elevated cholesterol levels.” http://www.faqs.org/nutrition/Smi-Z/Soy.html But too much soybean can also lead to risks of pancreatic damage and blood clots in the heart or lungs. http://ezinearticles.com/?Soybeans:--Too-Much-of-a-Good-Thing?&id=128393 I guess too much of anything is not good after all.

[Cindy]

Mo,
That is, in fact, a great way to look at soy – a cheap and easy birth control. I am sure a lot of guys would fall for it. Like many other contraceptives, soy alone is not absolutely effective (or at least questionably) and should be administered along with other methods to prevent pregnancy.

[Jon]

It is suspected that soy contains a chemical called "Touchi" that mimics the effects of a weak alpha-glucosidase inhibitor. Alpha-glucosidase inhibitors are a class of drugs used by diabetics to decrease their blood glucose levels. An example of one that is currently available on the drug market is Acarbose. With this alpha-glucosidase inhibiting effect, soy intake may play a great role in borderline diabetics. Alpha-glucosidase inhibitors’ mechanism of action revolves around the inhibition of enzymes that break down complex polysachrides into monosachrides, so that they can be absorbed in the small intestines. A borderline diabetic that as a slight elevation in hemoglobin A1C, (which is a long term marker for blood glucose levels) but not enough to constitute the use of biguanide such as Metformin (which is generally 1st line therapy for type 2 diabetics) may want to start eating a bit more soy each day.

[JoePBlack]

This is very interesting, but, I'm wondering, where exactly the research took place? Was it in Europe, America or Asia? I'm asking this because I live in an Asian country and because we eat soy daily in different kinds of foods. And as far as I know, we never have problems with fertility. In fact, we have a problem with overpopulation.

http://ezinearticles.com/?The-Benefits-of-a-Sperm-Count-Test&id=1948849
http://ezinearticles.com/?Separating-Facts-From-Myths---First-Step-For-Increasing-Sperm-Count&id=1955486

[RogueTangent]

I agree with JoePBlack. There must be other factors that affected the fertility of these men in the study.

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