Being overweight might take a toll on men's fertility, a new study suggests.


Researchers from the Stanford University School of Medicine and the Eunice Kennedy Shriver National Institute of Child Health and Human Development found an association between being overweight (indicated by body mass index and waist circumference) and having a decreased sperm count[1] , as well as decreased ejaculate volume.


"All aspects of semen quality[2] are important," study researcher Dr. Michael Eisenberg told Reuters, who first reported on the study. "Ejaculate has several chemicals that provide a safer environment for sperm. As such, if the volume is low it may be a problem."


The study, which is published in the journal Human Reproduction[3] , included data from around 500 couples who were part of the Longitudinal Investigation of Fertility and the Environment Study. They were recruited between 2005 and 2009 from Michigan and Texas. Data from 468 men were used for the study; the men had an average age of 31, an average BMI of 29.8 and an average waist circumference of 100.8 centimeters. (Body mass index is a ratio of height to weight; a BMI of 18.5 to 24.9 is considered normal weight, a BMI of 25 to 29.9 is considered overweight and a BMI of 30 and above is considered obese.)


Researchers found associations between higher BMI and waist circumference and declining ejaculate volume, as well as declining sperm count. They did not find associations between BMI and waist circumference and semen motility, vitality and concentration.


However, the "percentage of men with abnormal volume, concentration and total sperm increased with increasing body size," the researchers wrote in the study.


Previously, research presented at a meeting of the European Society of Human Reproduction and Embryology in 2008 showed that overweight and obese men had a higher likelihood of having low semen volume and sperm abnormalities[4] , the Associated Press reported. The researchers of that study, from the University of Aberdeen, noted, though, that they were unsure whether those findings translated into difficulty having children.


Just this October, Harvard researchers found that processed meat intake seems to be associated with decreased semen quality in the form of lower concentration of sperm. It also seemed to affect the way sperm looked and was structured.

[5]



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  • Canned food


    The common household chemical bisphenol A (BPA) can lower sperm counts and motility, according to<a href="http://www.rodale.com/bpa-and-unexplained-infertility"> a study</a> in Reproductive Toxicology. Food packaging is a major source of BPA, which can seep into the food. Most food cans are <a href="http://www.msnbc.msn.com/id/41025571/ns/health-sexual_health/t/shooting-blanks-surprising-sperm-killers/#.ULaH2WmMF9R">coated with BPA resin</a>, and acidic canned foods are especially risky.




  • Sex toys


    Certain plastics, including vinyl used in some sex toys, release phthalates — plastic-softening chemicals that have been <a href="http://news.harvard.edu/gazette/2003/05.22/18-semen.html">tied to lower reduced sperm count and quality</a>. Glass, silicone and green sex toys are a safer bet.




  • The shower


    Phthalates are found in many shampoos, soaps, deodorants and shaving creams. Look for natural, phthlate-free products instead.




  • Marijuana


    It's not surprising that smoking cigarettes is bad for sperm, but smoking weed isn't much better. Heavy marijuana smokers have been found to have <a href="http://news.bbc.co.uk/2/hi/health/3186686.stm">significantly lower sperm counts and sperm with bad swimming strategies</a>.




  • Stress


    Stress can cut sperm count dramatically by <a href="http://scienceblog.com/community/older/1997/B/199701021.html">inhibiting the production of testosterone</a>.




  • Booze


    Women aren't the only ones who should slow down on drinking while trying to conceive. Alcohol can <a href="http://menshealth.about.com/cs/stds/a/healthy_sperm.htm">inhibit sperm production</a> and lower sperm counts.




  • Receipts


    BPA is found on about 40 percent of cash register receipts, according to <a href="http://www.sccma-mcms.org/full+article/bisphenol+a+in+cash+register+receipts/">a 2010 University of Missouri study</a>. The chemical can penetrate skin or be passed from hand to mouth to the digestive track. Skip the receipt or wash your hands after signing.




  • Soy


    Isoflavones found in soy products <a href="http://www.isoflavones.info/">mimic estrogen</a>, and a <a href="http://www.washingtonpost.com/wp-dyn/content/article/2008/07/25/AR2008072502985.html">2008 study</a> linked soy consumption to significantly lower sperm counts. The soy food industry <a href="http://www.foxnews.com/story/0,2933,303160,00.html">disputed the study's findings</a>.




  • Contaminated fish


    Polychlorinated biphenyls (PCBs) are a group of toxic chemicals that have been banned but have accumulated in certain fish — especially predator fish and bottom-feeders. They are associated with <a href="http://www.epa.gov/teach/chem_summ/PCB_summary100809.pdf">decreased sperm counts and integrity</a>. Smaller, younger fish <a href="http://www.dhs.wisconsin.gov/eh/hlthhaz/fs/pcblink.htm#Which fish are safer to eat?">are considered safer</a>.




  • Nonstick pans


    Chemicals called perfluoroalkyl acids are used in the manufacturing of nonstick products such as Teflon, Gore-Tex and wax paper and can significantly lower sperm counts, according to <a href="http://www.rodale.com/male-infertility-and-nonstick-chemicals">a Danish study</a>.




  • Abstinence


    Of course not having sex at all won't help, but some couples abstain for days or weeks in hopes of saving sperm until the woman is ovulating. This doesn't work. Researchers have found that while it does take a day or two for sperm to replenish themselves after ejaculation, waiting any longer than that <a href="http://www.guardian.co.uk/uk/2003/jun/30/highereducation.sciencenews">can cause them to lose motility and change shape</a>.