Featured Research

from universities, journals, and other organizations

Soy Foods Are Associated With Lower Sperm Concentrations

Date:
July 24, 2008
Source:
European Society for Human Reproduction and Embryology
Summary:
Men who eat an average of half a serving of soy food a day have lower concentrations of sperm than men who do not eat soy foods. The association was particularly marked in men who were overweight or obese, the study found.

Men who eat an average of half a serving of soy food a day have lower concentrations of sperm than men who do not eat soy foods, according to new research. The association was particularly marked in men who were overweight or obese, the study found.

Related Articles


In the largest study in humans to examine the relationship between semen quality and phytoestrogens (plant compounds that can behave like the hormone, oestrogen), Dr Jorge Chavarro, a research fellow in the department of nutrition at Harvard School of Public Health, Boston, USA, and his colleagues found that men who ate the most soy food had 41 million sperm per millilitre less than men who did not consume soy products. (The "normal" sperm concentration for men ranges between 80-120 million/ml).

Isoflavones (daidzein, genistein and glycitein) are plant-derived compounds with oestrogenic effects that are found mainly in soy beans and soy-derived products. Animal studies have linked the high consumption of isoflavones with infertility in animals, but so far there has been little evidence of their effect in humans.

Dr Chavarro and his colleagues analysed the intake of 15 soy-based foods in 99 men who had attended a fertility clinic with their partners to be evaluated for sub-fertility between 2000 and 2006. They asked them how often and how much they had eaten in the previous three months; the foods included tofu, tempeh, tofu or soy sausages, bacon, burgers and mince, soy milk, cheese, yoghurt and ice cream, and other soy products such as roasted nuts, drinks, powders and energy bars.

Different foods have different levels of isoflavones in them, and so the researchers related the size of the serving to the particular food. For instance, a standard serving of tofu was 115g and for soy milk it was one cup (240 millilitres).

The men were divided into four groups according to their intake of soy foods and isoflavones. After adjusting for factors such as age, abstinence time, body mass index (BMI), alcohol and caffeine intake and smoking, Dr Chavarro found that men in the highest intake category had, on average, 41 million sperm/ml less than men who did not eat soy foods. "Men in the highest intake group had a mean soy food intake of half a serving per day: in terms of their isoflavone content that is comparable to having one cup of soy milk or one serving of tofu, tempeh or soy burgers every other day," he said.

"It is important to highlight that the figure of half a serving a day is the average intake for men in the highest intake group. Some men in this group had intakes of soy foods as high as nearly four servings per day."

The researchers found evidence that the association between soy food intake and sperm concentrations were stronger in men who were overweight or obese (and 72% of them were). They also found the relationship between soy foods and sperm concentration was strongest in men with the higher sperm concentrations. "The implication is that men who have normal or high sperm counts may be more susceptible to soy foods than men with low sperm counts, but this remains to be evaluated," explained Dr Chavarro.

The study does not reveal why soy foods have this effect on sperm, but Dr Chavarro speculates that increased oestrogenic activity may have an adverse effect on the production of sperm by interfering with other hormonal signals. This effect could be strengthened further in overweight and obese men because men with high levels of body fat produce more oestrogen than slimmer men, leading to high overall levels of oestrogen in the body and reproductive organs.

Soy foods are the most important source of phytoestrogens in people in the Western world, and the researchers say they were able to comprehensively assess the men's soy intake. They did not assess intake of isoflavones from other sources, such as bakery products made with soy flour. "However, the most likely effect of not assessing intake of these foods is that the associations reported in this study are attenuated," said Dr Chavarro.

The researchers say that the clinical significance of their research remains to be determined, and further randomised trials are needed.


Story Source:

The above story is based on materials provided by European Society for Human Reproduction and Embryology. Note: Materials may be edited for content and length.


Journal Reference:

  1. Jorge E. Chavarro , Thomas L. Toth , Sonita M. Sadio , and Russ Hauser. Soy food and isoflavone intake in relation to semen quality parameters among men from an infertility clinic. Human Reproduction, July 24, 2008 DOI: 10.1093/humrep/den243

Cite This Page:

European Society for Human Reproduction and Embryology. "Soy Foods Are Associated With Lower Sperm Concentrations." ScienceDaily. ScienceDaily, 24 July 2008. <www.sciencedaily.com/releases/2008/07/080723201241.htm>.
European Society for Human Reproduction and Embryology. (2008, July 24). Soy Foods Are Associated With Lower Sperm Concentrations. ScienceDaily. Retrieved October 25, 2014 from www.sciencedaily.com/releases/2008/07/080723201241.htm
European Society for Human Reproduction and Embryology. "Soy Foods Are Associated With Lower Sperm Concentrations." ScienceDaily. www.sciencedaily.com/releases/2008/07/080723201241.htm (accessed October 25, 2014).

Share This



More Health & Medicine News

Saturday, October 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

IKEA Desk Converts From Standing to Sitting With One Button

IKEA Desk Converts From Standing to Sitting With One Button

Buzz60 (Oct. 24, 2014) IKEA is out with a new convertible desk that can convert from a sitting desk to a standing one with just the push of a button. Jen Markham explains. Video provided by Buzz60
Powered by NewsLook.com
Ebola Protective Suits Being Made in China

Ebola Protective Suits Being Made in China

AFP (Oct. 24, 2014) A factory in China is busy making Ebola protective suits for healthcare workers and others fighting the spread of the virus. Duration: 00:38 Video provided by AFP
Powered by NewsLook.com
WHO: Millions of Ebola Vaccine Doses by 2015

WHO: Millions of Ebola Vaccine Doses by 2015

AP (Oct. 24, 2014) The World Health Organization said on Friday that millions of doses of two experimental Ebola vaccines could be ready for use in 2015 and five more experimental vaccines would start being tested in March. (Oct. 24) Video provided by AP
Powered by NewsLook.com
Doctor in NYC Quarantined With Ebola

Doctor in NYC Quarantined With Ebola

AP (Oct. 24, 2014) An emergency room doctor who recently returned to the city after treating Ebola patients in West Africa has tested positive for the virus. He's quarantined in a hospital. (Oct. 24) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins