The Wall Street Journal (8/5, Naik, Subscription Publication) reports on a study published in Cell, in which stem cells were used to convert sterile male mice to fertile. Embryonic stem cells were transformed into epiblast-like cells, then primordial germ cells. Those were transplanted into testes of sterile mice, where they became sperm, and then were used to fertilized eggs. Female mice were implanted with the embryos, which grew into viable, fertile offspring. Researchers hailed the finding, but the Journal notes that scientists do not know if this technique will work in humans. Researchers were also able to restore fertility by reprogramming adult mice cells, but the process involved oncogenic viruses, which resulted in some offspring dying of tumors. Currently, the researchers are working towards transforming embryonic stem cells into eggs.
The UK’s Telegraph (8/5, Collins) notes, “The technique may not fall foul of British laws which ban the use of lab-made mature sperm in fertility treatments, because the scientists only created germ cells which produced sperm naturally.” Fertility expert Allan Pacey said, “The philosophy of the law is to stop that kind of thing happening. But in this case you’re not technically creating sperm, so it might be that you can sidestep this regulation. It all depends on definition.”
Also covering the story are Reuters (8/5, Lyn), the UK’s Independent (8/5, Connor), and BBC News (8/5, Parkinson).
The New York Times (7/21, A17, Belluck) reports, “Scientists say they have found a potential cause for a number of otherwise unexplained cases of male infertility: the absence of a protein that coats sperm and allows them to reach an egg more easily.” Researchers say that “many men may be able to ‘overcome the mutation’ because other factors, like the shape, number or mobility of their sperm, help them fertilize the egg.” The study, published in Science Translational Medicine, found that worldwide, about 50% of men are heterozygous for the defective mutation and form normal sperm while 25% are homozygous and form sperm that cannot swim well. The researchers also studied 500 couples in China, finding that birth rates are 30% lower for the homozygous men.
Bloomberg News (7/21, Lopatto) reports, “Infertile men may have a gene defect that takes away a protein that cloaks and protects sperm against a woman’s immune system while traveling to the egg, according to a study that offers a new explanation for some male infertility.” The mutation results in the sperm being less able to move through simulated cervical mucus.
Reuters (7/21, Lyn) reports that researcher Theodore Tollner suggested that if the male partner is found to have this mutation, doctors helping the couple conceive should consider using IFV or intrauterine insemination. Reuters notes that experts have historically blamed low sperm count for infertility in men.
The Time (7/20, Szalavitz) “Healthland” blog reported that the gene is normally coated onto the sperm coat along with other proteins and sugars, during the sperm’s passage in the epididymis. UC Davis professor Charles Bevins noted that the mutation in DEFB126 is common, and that there may be an unknown advantage for men carrying one copy of the mutation. As for treating infertility, “the research also suggests that a technique to add the missing protein to the sperm could be helpful. Researchers have already tried this approach with the sperm of nonhuman primates and it could potentially be applied as a vaginal gel before intercourse.”
WebMD (7/20, Boyles) reported that this discovery was made “during an unsuccessful attempt to develop a contraceptive vaccine using…DEFB126.” When the researchers cloned the gene, they “detected the genetic mutation that keeps DEFB126 from performing this function.” The Vancouver Sun (7/21, Pemberton) and Sacramento Bee (7/21, La) also cover this story.
The AP (3/8/11, Neergaard) reports, “Many of the cancer treatments that can save patients’ lives also may cost their ability to have babies later in life.” Although young adults have options such as sperm banking or freezing embryos or eggs, children “diagnosed before puberty don’t.” And with childhood cancer “survival reaching 80 percent, there’s a growing need to find ways to preserve these youngsters’ fertility.” Dr. Kyle Orwig of the University of Pittsburgh says there are “viable options, and they are on the doorstep.” Dr. Orwig is leading a study to “store the stem cells boys harbor that later on will produce their sperm,” with a goal to eventually, “transplant the cells back.”
HealthDay (3/4/11, Gardner) reported, “New research contends that the distance between the posterior base of the scrotum and the anus can predict the strength of a man’s sperm population.” A study in the journal Environmental Health Perspectives found that men who have a shorter perineal length, or “anogenital distance (AGD), have lower sperm counts, poorer quality sperm, lower sperm concentrations and lower motility.” The researchers took two measures of “AGD, along with sperm count and concentrations, sperm shape and sperm motility, in 126 college students.” The median AGD was “about 52 millimeters so men who had an AGD below this level were more than seven times more likely to have low sperm concentration in the subfertile range.” Reuters (3/7, Zabarenko) also covered the study.
“Vasectomy Reversal May Relieve Pain In Men Who Develop Postvasectomy Pain Syndrome.The Los Angeles Times (1/18/11, Maugh) “Booster Shots” blog reports, “Some poor men are apparently allergic to their own semen, developing a mysterious flu-like illness after they have an ejaculation,” according to research in the Journal of Sexual Medicine. Symptoms of the condition, known as post-orgasmic illness syndrome (POIS) include “feverishness, runny nose, extreme fatigue and burning eyes, which can last for up to a week.” Although some physicians had “suggested that the disorder was psychosomatic,” Marcel Waldinger of the Utrecht University in the Netherlands colleagues “demonstrated in two papers” in the journal that POIS is “allergic in nature and that it might be possible to desensitize men to the problem.
Medscape (6/7/10, Stein) reported, “A vasectomy reversal can relieve pain in most men who develop postvasectomy pain syndrome, according to data presented…at the American Urological Association 2010 Annual Scientific Meeting.” In fact, after reviewing the medical records of 45 patients, University of Southern California researchers found that “75% of reversal patients…experienced complete relief, 10% had greater than a 30% reduction in symptoms, and 10% had no change in symptoms.” Thus, lead investigator explained, “We need to tell our patients that they don’t have to be debilitated by their pain, they don’t have to stop exercising for the rest of their lives, they don’t have to have pain every time they sit down for a half hour, and they don’t have to have it every time they ejaculate.”
HealthDay (4/28/10, Preidt) reported, “Two proteins in a family of proteins called PLA2s play a vital role in sperm function and fertility in mice,” according to two papers in the Journal of Clinical Investigation. “In one study, Japanese researchers found that the protein sPLA2-III is expressed in an area of the testis called the proximal epididymal epithelium,” and “male mice that lacked the protein had low levels of fertility because their sperm did not mature properly, which resulted in decreased motility and decreased ability to fertilize eggs.” Meanwhile, researchers in France noted that “male mice that lacked the protein group X secreted PLA2 (also known as mGX) produced smaller litters than normal, and that sperm from mGX-deficient mice were not efficient at fertilizing eggs.”
BBC News (2/5/10) reported, “Scientists have long known that a sperm’s level of activity is governed by internal pH.” But, “in order to increase its pH and become more alkaline, the sperm needs to jettison protons.” Now, researchers at the University of California-San Francisco “have found pores on its surface which allow it to do precisely that.” In other words, the “tiny little pores that act like ‘gateways’ in the sperm’s tail, allowing acidic protons to seep out and boosting the sperm’s movement,” the UK’s Telegraph (2/4, Alleyne) reported. “These ‘gateways’ are in turn controlled by a molecule known as Hv1.” Investigators also noted that “both a lack of zinc outside the sperm and exposure to a natural cannabis-like chemical called anandamide can cause the pores to open,” the UK’s Press Association (2/4) reported. “The link with anandamide might explain why smoking cannabis has been associated with impaired male fertility,” according to the paper in Cell. “‘Marijuana likely activates sperm prematurely, leaving them burnt out in a matter of hours,’ said study leader Dr Yuriy Kirichok.”
MedWire (1/4/10, Grasmo) reports that, according to a study publis
hed online in the journal Human Reproduction, “systemic oxidative stress resulting in increased lipid peroxidation and an altered fatty acid profile may play a part in the mechanism responsible for male idiopathic infertility.” After measuring “blood and seminal plasma levels of arachidonic acid (AA), docosahexaenoic acid (DHA), and thiobarbituric acid reactive species (TBARS) — a marker of peroxidative damage –in 38 normozoospermic males from infertile couples (NSI-males) and” comparing “them with those seen in 17 fertile males,” researchers found that “only NSI-males showed a positive correlation between TBARS and AA in both blood and seminal plasma, and a negative correlation between TBARS and DHA in blood plasma.”
HealthDay (11/20/09, Dotinga) reported that, according to findings appearing in the Nov. 18 issue of the Journal of the American Medical Association, “testicular stem cells can be cultured and multiplied, potentially creating sperm.” In the study of “six patients during prostate cancer surgery,” researchers succeeded in coaxing stem cells from the patients’ testicles to multiply. For “men made infertile by childhood cancer treatments,” the finding “raises the prospect” that they “could impregnate women by having the cells implanted in their testicles,” the researchers noted. But, they added that “the cells came from adult men, not boys who haven’t reached puberty,” and it remains unclear whether “the cells can create sperm in humans.” Furthermore, “it’s possible that the cells could transmit cancer to the recipients.”
The UK’s Daily Mail (10/26/09) reported that UK and Danish researchers have “discovered why older men are more likely to have children with health problems” — spermocytic seminomas. Although the “testicular tumors” are benign, the “researchers believe they can change germ cells that create sperm. This may cause genetic mutations in their children’s DNA resulting in rare growth disorders,” such as “achondroplasia and Apert, Noonan and Costello syndromes, as well as some conditions causing stillbirth.” The findings, appearing in Nature Genetics, “may also help explain why common diseases, including breast cancer, autism, and schizophrenia, seem to be more frequent in the offspring of older fathers.” Lead investigator Andrew Wilkie says that “similar — but milder — mutations might contribute to these diseases.” The UK’s Telegraph (10/26, Irvine) also covered the breakthrough.
HealthDay (10/26/09, Dotinga) reported that a paper appearing in the Journal of Experimental Medicine indicates that “sperm, not just semen, can transmit the virus that causes AIDS to immune cells in the body.” Researchers at the University of Buenos Aires explained that the “virus attaches to the surface of sperm and can be transmitted to immune cells” by “passing through tiny abrasions in the vagina or anus or perhaps through another method.” What’s more, the “slightly acid environment, which they likened to that in the vagina after sexual intercourse, boosts the likelihood of infection of these cells.”
The UK’s Telegraph (10/7/09, Chivers) reported that Austrian researchers have “found that spermidine, a compound that is found in sperm, slows aging processes and increases longevity in yeast, flies, worms, and mice, as well as human blood cells, by protecting cells from damage.” Because of autophagy, “spermidine concentration has been shown to decline with age.” But, increasing levels “suppressed various processes associated with aging, as well as reducing free radicals and increasing lifespan.” In fact, “treated fruit flies lived 30 percent longer than untreated ones, while worms lived 15 percent longer.”
The Chicago Tribune (9/9/09, Ahern) reports that, according to a study of 133 patients published in the Journal of Reproductive Medicine, many infertile couples may “seek alternative treatments, including acupuncture, herbal remedies, and religious intervention.” Specifically, researchers at the Ohio State University Medical Center found that “62.2 percent [of respondents] said they used alternative methods. Prayer and having people pray on the patients’ behalf was the method for nearly 34 percent of respondents.” The researchers found that “the second-highest response, 29 percent, was changes in sexual practice. Dietary changes, massage, yoga, other stress reducing efforts also were mentioned.” Lead author Jonathan Schaffir, MD, “said that in general, most alternative treatments are harmless, but cautioned that natural vitamins or herbal teas may lead to illness or interfere with fertility efforts.”
HealthDay (8/6/09, Preidt) reported, “Two proteins that play a major role in reverting adult sperm cells back into stem cells have been identified by” a team at Johns Hopkins University who worked with “genetically altered male fruit flies.” During the experiment, detailed online in Cell Stem Cell, investigators “reduced the activity of two proteins called Jak and STAT in the testis.” That is, they “reduced the stem cell population in the flies’ testis to zero and found that only 60 percent of testis in the genetically altered flies regained stem cells, compared with 97 percent of testis in normal flies.” In other words, “interfering with Jak-STAT signaling interferes with the process of dedifferentiation,” explained lead investigator Erika Matunis. The finding “may help in efforts to develop effective stem cell therapies.”
In a fro
nt-page article, the Financial Times (7/8/09, A1, Cookson) reports, “Scientists have created human sperm for the first time from stem cells,” a breakthrough that may one day “enable infertile men to have children, while provoking another ethical debate on the progress of reproductive biology.” The process began with Iran native Karim Nayernia who “started his synthetic sperm research” in Germany, which apparently “led to stories about ‘an end to men,’ enabling lesbian couples to have their own biological children without male involvement.” He said, however, that those opinions “were based on a ‘misunderstanding,’” and so he pressed on.
Three years ago, Prof. Nayernia and his team at the University of Göttingen “became the first to produce viable sperm from mouse embryonic stem cells which were used to produce seven live offspring,” according to the UK’s Independent (7/8, Laurance). “However, the baby mice died shortly after birth.” Sometime soon after, in 2006, he left Germany because embryo experiments there were banned. He landed in England where “under current legislation, researchers are banned from using sperm (or eggs) produced in the laboratory — known as in-vitro derived (IVD) sperm — to treat patients. But it is permitted for research purposes.”
It is at England’s Newcastle University that Prof. Nayernia, alongside researchers at the North East England Stem Cell Institute, made his breakthrough, according to Time (7/7, Park). The “achievement, described in the journal Stem Cells and Development, comes just 11 years after the first human-embryonic-stem-cell line was created — an eyeblink in scientific terms.” Notably, Nayernia’s IVD sperm “are not exactly like naturally occurring sperm, though they do bear four important similarities to the cells created in the testes. They contain half the number of chromosomes of other human cells (somatic cells contain 46 chromosomes, but egg and sperm cells have only 23, since they combine their genetic payloads during fertilization); they possess a head and a tail; they contain proteins essential for activating the egg during fertilization; and they swim, or move as sperm do in seeking out eggs to fertilize.”
As for the science behind the experiment, “Nayernia created a cocktail of chemicals and vitamins” — including retinoic acid — “that turned human stem cells into sperm,” the UK’s Daily Mail (7/8, MacRae) reports. They were then “‘tagged’ with a genetic marker which enabled the scientists to identify and separate so-called ‘germline’ stem cells from which eggs and sperm are developed,” according to BBC News (7/8, Walsh), the AFP (7/8) and the UK’s Press Association (7/8) and the Guardian (7/8, McVeigh) also cover the story.
WebMD (6/30/09, Hitti) reported, “Men with a history of fertility problems may curb DNA-damaged sperm by ejaculating for seven days in a row,” according to a report titled “Keep the River Flowing” written by David Greening, MD, of Sydney IVF in Australia. Dr. Greening developed his theory after studying “118 men with a history of infertility, recurrent miscarriage, or repeated in vitro fertilization failure (IVF) who had DNA damage in more than 15 percent of their sperm from sperm samples.” After having the men “ejaculate daily for seven consecutive days,” their sperm samples “showed that 81 percent of the men had a reduction in DNA sperm damage.” Dr. Greening speculated that such reductions occurred “because the sperm spent less time in the male reproductive system.”
BBC News (6/30/09, Wilkinson) explained that “the warm environment” in the male reproductive system “could also make them more sluggish after a while.” In addition, “sperm come under attack by free radicals — small reactive molecules which can damage DNA and cause cell death — in the tube that stores and carries sperm away from the testes.” Dr. Greening also pointed out that his work may “have implications for couples undergoing IVF, as men are commonly told to abstain from sex for a couple of days to try and boost sperm numbers.”
BBC News (6/29/09) reported, “Professional cyclists should consider freezing their sperm before embarking on their careers,” because researchers in Spain have discovered that “sperm quality drops dramatically with rigorous training.” Specifically, “those who cover more than 186 miles (300km) a week on their bikes have less than four percent normal-looking sperm,” a level where men would certainly “have ‘significant fertility problems.’” The team at the University of Cordoba Medical School explained that “heat from wearing tight clothing, friction of the testes against the saddle, and stresses on the body from the sheer amounts of energy needed to do such rigorous exercise, could all contribute to poor sperm quality.” Notably, “other studies had shown very high levels of exercise affected fertility in both men and women.
MedWire (3/2/09, Grasmo) reported that “men who are infertile appear to have an increased risk for developing testicular germ cell cancer,” according to a study appearing in the Archives of Internal Medicine. For the study, researches “analyzed data from 22,562 male partners of couples seeking fertility treatment during 1967-1998, and linked them to the California Cancer Registry.” They “found that 4,549 of these men had male factor infertility, and a total of 34 postinfertility-diagnosis cases of histologically confirmed testicular cancer were identified.” Upon analysis, “men in couples seeking treatment for infertility were 1.3 times more likely to develop testicular cancer compared with the general population.” Moreover, “men with male factor infertility had 2.8 times the risk for testicular cancer compared with those without this condition.” The researchers concluded that “a plausible explanation is that a common exposure underlies infertility and testicular cancer.
The UK’s Telegraph (1/19/09, Gray) reported, “Anti-androgens, that are found in a number of medicines including cancer treatments and pesticides used in agriculture, were found in 30 rivers across England,” according to a recent study. Other “studies have already shown that the female sex hormone estrogen is causing the feminization of fish, and in some cases, can lead to male fish changing sex.” For this study, British researchers analyzed “more than 1,000 fish in rivers across the UK” over the course of three years. They found that “anti-androgens are also causing male fertility problems in a ‘double whammy’ for the fish.”
The investigators “have yet to find the source of the…anti-androgens, but believe they could come from pesticides, industrial pollution, or pharmaceutical drugs,” the UK’s Daily Mail (1/19, Derbyshire) added. The authors warned that “anti-androgens can induce a lot of conditions we see in humans, such as low fertility and an increase in genital deformities, very readily.
In the Discover (12/22/08) 80beats blog, Eliza Strickland wrote, “To truly assess the risks posed by a ubiquitous group of chemicals,” called phthalates, “found in everything from vinyl shower curtains to bug spray, researchers need to study their cumulative impact on human health,” according to a report from the National Research Council. “In rodent studies exposure to phthalates has been shown to interfere with the development of the male reproductive system, causing infertility, reduced sperm production, undescended testes, penile birth defects, and other reproductive-tract malformations,” Strickland noted. “Traditionally, health agencies have studied the risk of each chemical individually, but experts say such a process doesn’t accurately reflect human exposure.” In fact, “studies from the Centers for Disease Control and Prevention and independent scientists have found phthalates in virtually everyone, including pregnant women and babies.”
UroToday.com (11/21/08) The authors previously reported an effect of antidepressants on semen parameters. The current study was designed to assess/confirm their prior report of the effects of an SSRI, paroxetine (Paxil), on semen parameters. This was a prospective clinical trial involving 35 healthy male volunteers ages 18-65. SA were obtained prior and 2 weeks and 4 weeks after SSRI initiation. Paroxetine was given for 5weeks: 10mg QD week 1, 20mg QD week 2, 30mg QD weeks 3-4, and 20mg QDweek 5. Standard WHO evaluation of semen parameters were assessed. TUNELassays were performed on baseline and week 4 semen samples to evaluate DNA fragmentation. Semen parameters and TUNEL assays for each individual were compared at each time point. As opposed to prior report, semen parameters (volume, concentration, motility, morphology) were not significantly altered during SSRI treatment. However, mean DNA fragmentation TUNEL score was significantly higher on SSRI (30.3%) versus baseline (13.8%). Multivariate logistic regression, correcting for age and body mass index, confirmed that SSRI treatment was significantly correlated with increased DNA fragmentation Up to 35% of men noted significant changes in erectile function and up to 47% of subjects reported ejaculatory difficulties while on paroxetine. Conclusions: In volunteer male subjects with normal semen parameters, paroxetine induced abnormal sperm DNA fragmentation in a significant proportion of patients. This effect occurred without a measurable effect on semen parameters. The fertility potential of a substantial proportion of men on paroxetine may be adversely affected by these changes in sperm DNA integrity. Editorial Comment (Harris Nagler, MD): This is an interesting study. The data refutes prior report by the same group indicating the effect on gross semen parameters and sperm transport mechanisms. None of these parameters were significantly different from baseline. However, this study noted an interesting and potentially significant change in DNA fragmentation. However, the mean DNA sperm fragmentation of 30.3% is at the upper limit of normal. The authors hypothesize that this may reflect delayed transport of sperm. The reported effect on sexual dysfunction is not surprising. Further studies are needed to assess the potential clinical significance of this interesting observation.
MedPage Today (11/20/08, Johnson) reported that “several new studies suggest that exposure to bisphenol A may reduce fertility in both men and women.” For instance, Harvard University researchers led by Shelley Ehrlich, M.D., discovered an “association between men with higher levels of urinary bisphenol A (BPA) and poorer semen quality.” Specifically, “90 percent of the men had urinary evidence of BPA exposure at a mean concentration of 2.4 mg/L,” a finding that “is in line with a much larger study published in Environmental Health Perspectives.” That study found “BPA in 93 percent of urine samples from a reference population of 2,517.” In “Dr. Ehrlich’s study, men with BPA concentrations above the mean of the study group had 3.5 times greater odds of having low sperm concentration, compared with men with exposure levels below the mean.” Likewise, “the men with higher exposure had lower sperm motility and more abnormal sperm morphology.” The “findings did not reach statistical significance, she said, but they are suggestive of what has already been shown in animal studies.”
MedPage Today (11/20/08, Johnson) reported that “in vitro fertilization is associated with an increased risk of ovarian malignancies, particularly borderline tumors (also called tumors of low malignant potential) — but the absolute risk of the uncommon cancers remains small,” according to findings presented at the American Society for Reproductive Medicine’s meeting. This theory, explained researchers in the Netherlands, “hinges on the fact that superovulation, ovarian puncture, and high levels of gonadotropins cause increased damage to the ovary.” In short, “the cumulative risk of ovarian tumors before age 55 is 0.45 percent in the general population,” however, “this risk increases to about 0.71 percent after in vitro fertilization.” These findings are based on a “mail questionnaire [that] was used to collect data on reproductive and lifestyle factors.”
New Scientist (9/24/08, Aldhous) reported, “Antidepressants taken by millions of men could be impairing their fertility by causing damage to the DNA in their sperm,” according to research that will be presented “in November at a meeting of the American Society for Reproductive Medicine in San Francisco.”
According to the U.K.’s Telegraph (9/24, Alleyne), “The findings, published in New Scientist, once again throw the spotlight on the most commonly prescribed anti-depressants known as selective serotonin re-uptake inhibitors (SSRIs) that have also been linked to suicide in the past.” For the study, Professor Peter Schlegel and Dr. Cigdem “Cori” Tanrikut of the Cornell Medical Center in New York City “gave 35 healthy men doses of paroxetine, a popular SSRI sold as Seroxat and Paxil, over five weeks and examined their sperm. Superficially, the men’s sperm seemed healthy — the amounts of sperm and semen, and the shape and motility of sperm, were all normal.”
In continuing coverage from a previous edition of the Daily Scope, HealthDay (7/23/08, Reinberg) reported that according to a study published in the journal Radiology, varicocele embolization can correct a “condition, called varicocele,” which “is a network of tangled blood vessels in the scrotum which prevents the normal circulation of blood through the veins in the testicles,” and can cause male infertility. The study involved “223 infertile men with at least one varicose vein” who “had healthy partners with whom they wanted to have a baby.” The results showed that the procedure improved “sperm motility and sperm count…significantly.” Dr. Hossein Sadeghi-Nejad, of the University of Medicine and Dentistry, New Jersey, “thinks this procedure can be useful.” But, he added that “there are drawbacks to embolization. … These include a steep learning curve to get used to doing the procedure and the danger of prolonged or misdirected radiation, especially if there are varicoceles on both sides of the scrotum.”
The BBC (7/24/08) reports, “A regular diet of even modest amounts of food containing soy may halve sperm concentrations,” according to a study published in the journal Human Reproduction. Investigators examined “the diets of 99 men who had attended a fertility clinic with their partners and provided a semen sample.” Researchers divided the patients “into four groups depending on how much soy they ate, and when the sperm concentration of men eating the most soy was compared with those eating the least, there was a significant difference.” The results indicated that “[t]he ‘normal’ sperm concentration for a man is between 80 and 120 million per milliliter, and the average of men who ate on average a portion of soy-based food every other day was 41 million fewer.”
According to the U.K.’s Guardian (7/24, Sample), “The apparent fall in sperm count is unlikely to make healthy men infertile, but some experts said it could have a significant impact on those already with lower than average sperm counts.” Men must “produce fewer than 20 million sperm per ml” to be “regarded as clinically subfertile.” Currently, “20 percent of young Europeans having a low sperm count, while levels of soya have risen steadily in the western diet since the 1940s because it is a cheap source of protein,” and can be “found in two-thirds of manufactured food including biscuits, sweets, pasta and bread.”
The U.K.’s Daily Mail (7/24/08) notes, “It is thought that soya compounds called isoflavones, which mimic the female sex hormone estrogen, are behind the effect,” as “[a]nimal studies have [also] linked a high consumption of isoflavones with infertility.” The men in this current study were “questioned…about consumption of 15 soya-based foods” such as “tofu, tempeh, soy sausages, bacon, burgers and mince, soy milk, cheese, yoghurt and ice cream, and soya products such as roasted nuts, drinks, powders and energy bars.”
Highlighting details of the survey’s results, WebMD (7/23/08, Hitti) reported, “Almost all of the men — 90 percent — had sperm concentrations that were within the normal range, and 42 percent of the men had normal semen analyses, which include sperm shape and motion in addition to sperm concentration.” Furthermore, “[m]ost of the men — 39 of them — said they hadn’t eaten any soy foods during the previous three months,” while “[a]nother 18 men said they ate soy foods less than twice a month, 22 said they ate soy foods between twice a month and twice a week, and 20 said they ate soy foods at least twice a week.”
HealthDay (7/23/08, Reinberg) added that “the researchers found that the link between soy and sperm concentration was stronger among overweight and obese men,” because they “produce more estrogen than thinner men, and soy may increase those estrogen levels even further.” And, “the link between soy and sperm concentration was strongest in men with higher sperm concentrations,” as those “who have normal or high sperm counts may be more susceptible to soy foods than men with low sperm counts.”