Researchers from the Sleep Heart Health Study (SHHS) report that the risk of stroke appears in men with mild sleep apnea and rises with the severity of sleep apnea. Men with moderate to severe sleep apnea were nearly three times more likely to have a stroke than men without sleep apnea or with mild sleep apnea. The risk from sleep apnea is independent of other risk factors such as weight, high blood pressure, race, smoking, and diabetes.

They also report for the first time a link between sleep apnea and increased risk of stroke in women. Obstructive Sleep Apnea Hypopnea and Incident Stroke: The Sleep Heart Health Study, was published online March 25 ahead of print in the American Journal of Respiratory and Critical Care Medicine.

Stroke is the second leading cause of death worldwide. “Although scientists have uncovered several risk factors for stroke — such as age, high blood pressure and atrial fibrillation, and diabetes — there are still many cases in which the cause or contributing factors are unknown, ” noted NHLBI Acting Director Susan B. Shurin, M.D. “This is the largest study to date to link sleep apnea with an increased risk of stroke. The time is right for researchers to study whether treating sleep apnea could prevent or delay stroke in some individuals. ”

Conducted in nine medical centers across the United States, the SHHS is the largest and most comprehensive prospective, multi-center study on the risk of cardiovascular disease and other conditions related to sleep apnea. In the latest report, researchers studied stroke risk in 5,422 participants aged 40 years and older without a history of stroke. At the start of the study, participants performed a standard at-home sleep test, which determined whether they had sleep apnea and, if so, the severity of the sleep apnea.

Researchers followed the participants for an average of about nine years. They report that during the study, 193 participants had a stroke — 85 men (of 2,462 men enrolled) and 108 women (out of 2,960 enrolled).

After adjusting for several cardiovascular risk factors, the researchers found that the effect of sleep apnea on stroke risk was stronger in men than in women. In men, a progressive increase in stroke risk was observed as sleep apnea severity increased from mild levels to moderate to severe levels. In women, however, the increased risk of stroke was significant only with severe levels of sleep apnea.

The researchers suggest that the differences between men and women might be because men are more likely to develop sleep apnea at younger ages. Therefore, they tend to have untreated sleep apnea for longer periods of time than women. “It’s possible that the stroke risk is related to cumulative effects of sleep apnea adversely influencing health over many years, ” said Susan Redline, M.D., MPH, professor of medicine, pediatrics, and epidemiology and biostatistics, at Case Western Reserve University in Cleveland and lead author of the paper.

“Our findings provide compelling evidence that obstructive sleep apnea is a risk factor for stroke, especially in men, ” noted Redline. “Overall, the increased risk of stroke in men with sleep apnea is comparable to adding 10 years to a man’s age. Importantly, we found that increased stroke risk in men occurs even with relatively mild levels of sleep apnea. ”

“Research on the effects of sleep apnea not only increases our understanding of how lapses of breathing during sleep affects our health and well being, but it can also provide important insight into how cardiovascular problems such as stroke and high blood pressure develop,” noted Michael J. Twery, Ph.D., director of the NIH National Center on Sleep Disorders Research, an office administered by the NHLBI.

The new results support earlier findings that have linked sleep apnea to stroke risk. SHHS researchers have also reported that untreated sleep apnea is associated with an increased risk of high blood pressure, heart attack, irregular heartbeats, heart failure, and death from any cause. Other studies have also linked untreated sleep apnea with overweight and obesity and diabetes. It is also linked to excessive daytime sleepiness, which lowers performance in the workplace and at school, and increases the risk of injuries and death from drowsy driving and other accidents.

More than 12 million American adults are believed to have sleep apnea, and most are not diagnosed or treated. Treatments to restore regular breathing during sleep include mouthpieces, surgery, and breathing devices, such as continuous positive airway pressure, or CPAP. In people who are overweight or obese, weight loss can also help.

These treatments can help improve breathing and reduce the severity of symptoms such as loud snoring and excessive daytime sleepiness, thereby improving sleep-related quality of life and performance at work or in school. Randomized clinical trials to test whether treating sleep apnea lowers the risk of stroke, other cardiovascular diseases, or death are needed.

“We now have abundant evidence that sleep apnea is associated with cardiovascular risk factors and diseases. The next logical step is to determine if treating sleep apnea can lower a person’s risk of these leading killers, ” said Redline. “With stimulus funds, our research group is now developing the additional research and resources to begin answering this important question. ”

Through funding from the American Recovery and Reinvestment Act, the NHLBI is awarding approximately $4.4 million to Redline to conduct the first NIH-funded comparative effectiveness study of treatments for sleep apnea. In the two-year multi-center pilot study, SHHS researchers and others will compare the cardiovascular effects of adding either CPAP or supplemental oxygen during sleep to standard care in patients with moderate to severe sleep apnea who are at high risk for cardiovascular disease events such as heart attack or stroke.

The SHHS draws on a resource of existing, well-characterized and established cohort studies of cardiovascular and lung diseases supported by the NHLBI. A cohort is a well-defined group of participants who share a common background or characteristic and are being followed for an extended length of time. For this study, SHHS researchers add assessment of sleep to data collection in ongoing studies including the Atherosclerosis Risk in Communities (ARIC) Study sites in Washington County, Md., and Minneapolis; the Cardiovascular Health Study (CHS) sites in Sacramento, Calif., Washington County, Md., and Pittsburgh; the Framingham Offspring and Omni cohorts in Framingham, Mass.; the Health and Environment and Tucson Epidemiologic Study cohorts in Tucson, Ariz.; the Strong Heart Study sites in Arizona, Oklahoma, and South Dakota; a Reading Center at Case Western Reserve University in Cleveland, Ohio; and the University of Washington in Seattle (Coordinating Center 1994-1999). The Johns Hopkins University Bloomberg School of Public Health serves as the Coordinating Center.

“The body has built-in mechanisms that try to counter disease progression, and we now have a mechanism that can be [used] to selectively blunt an immune response without causing a systemic response,” said the study’s senior author, Dr. Pere Santamaria, a professor at the Julia McFarlane Diabetes Research Centre at the University of Calgary in Alberta.

What’s more, Santamaria said, the technique developed for the diabetes vaccine may be applicable to other autoimmune diseases, such as multiple sclerosis and rheumatoid arthritis.

So far, the research has only been conducted in mice. “We don’t yet know if it will work in humans, but we’re very excited and think this offers hope,” said Santamaria.

Type 1 diabetes is an autoimmune disease. That means that the body’s immune system, which usually targets invading unwanted cells, such as bacteria, mistakenly destroys healthy cells. In the case of type 1 diabetes, the immune system destroys the insulin-producing beta cells in the pancreas. This knocks out the body’s ability to produce insulin, the hormone that helps convert blood sugar to energy for cells in the body. So, people with type 1 diabetes must inject insulin multiple times a day, every day, to stay alive.

“Autoimmune diseases, like type 1 diabetes, multiple sclerosis and rheumatoid arthritis, are caused by an overactive immune system. Normally, the immune system helps us fend off cancer and infection, but in some people, it becomes overaggressive,” Santamaria explained.

Although there are medications available that can dampen the entire immune response, these medications can create additional problems, such as an increased risk of cancer and serious infection.

However, the Canadian researchers discovered that the body doesn’t just allow the autoimmune aggression to go unchecked. There is a counter-mechanism that produces immune system cells to try to fight the rogue immune cells that are creating the damage in type 1 diabetes.

But these cells — know as memory-like autoregulatory T cells — aren’t as strong as the rogue cells and so they quickly become overwhelmed.

Using a “nanotechnology-based” vaccine, the researchers were able to boost the effects of the weaker immune cells, which allowed them to stop the damaging immune cells from attacking. The vaccine consists of nanoparticles — spheres thousands of times smaller than a single cell of the body — “coated” with antigens that bind to molecules used to stimulate certain T cells.

“With this nanovaccine, we engage the weak immune cells and make them multiply and divide, and then they can counter the autoimmune response without impairing systemic immunity,” said Santamaria.

Instead of directly attacking the stronger cells, the autoregulatory T cells turn off the signal that tells the stronger immune cells to attack, effectively stopping the destruction of the beta cells.

Santamaria said it’s not clear yet if this vaccine would be a one-time treatment, or would need to be administered periodically. He said it’s likely additional treatment might be necessary.

Santamaria said the next step in his work is to produce the drug in a version that can be used in clinical trials on humans.

Teodora Staeva, director of Immune Therapies for the Juvenile Diabetes Research Foundation International, called the new research “a very novel therapeutic approach that seems to have great potential.”

“A lot of work remains to be done. This therapy has the promise of being safer — although that has to be proven in toxicology studies — because it specifically targets the cells that are causing the problems,” Staeva said.

Staeva said that if this vaccine proves itself in human studies, it has the potential to help both newly diagnosed type 1 diabetics and those who’ve had the disease for years. But, she said, in people who’ve had type 1 for a long time, beta cell transplantation might be necessary.

Results of the study were published online April 8 and are to appear in the April 23 print version of the journal Immunity.

“Phosphine fumigants are poisons and must be kept away from where our children live,” said Steve Owens, assistant administrator of EPA’s Office of Prevention, Pesticides and Toxic Substances. “These new safeguards prohibit the use of these toxic pesticides near homes and impose restrictions to protect our families from exposure to them.”

Aluminum and magnesium phosphide fumigants are used primarily to control insects in stored grain and other agricultural commodities. They also are used to control burrowing rodents in outdoor agricultural and other non-domestic areas. The fumigants are restricted to use by specially trained pesticide applicators and in only narrow circumstances.

EPA is expediting approval of the new labels to reduce the potential for accidental poisonings. The primary manufacturer is voluntarily implementing the changes. EPA will apply these changes to all aluminum and magnesium phosphide products.

More information about aluminum and magnesium phosphide: http://www.epa.gov/oppsrrd1/reregistration/alphosphide/.

This coming fall, the U.S. National Institutes of Health will start enrolling participants in the largest trial thus far to see if lowering blood pressure even below current recommendations can reduce not only the risk of age-related cognitive decline, but also the risk of cardiovascular and kidney diseases.

The Systolic Blood Pressure Intervention Trial (SPRINT) will involve 7,500 people aged 55 and over who will be followed for a minimum of four years. The NIH is investing $114 million in the endeavor.

“We have a number of effective and safe medications to lower blood pressure,” said Dr. Lawrence Fine, chief of the clinical applications and prevention branch in the division of cardiovascular sciences at the National Heart, Lung, and Blood Institute. “For the average person right now, the recommendation is a blood pressure of 140/90 or lower. SPRINT will compare that with a goal of 120 as the top number. Will the rate of dementia for people in the lower-goal arm be lower than standard?”

Current clinical guidelines recommend systolic pressure (the top number in a blood pressure reading) of less than 140 millimeters of mercury (mm Hg) for healthy adults, and 130 mm Hg for adults with kidney disease or diabetes.

“Hypertension is very easy to medicate and very easy to measure, so they want to see if just by modifying that simple thing they could reduce the incidence of dementia,” said Ian Murray, an assistant professor of neuroscience and experimental therapeutics at the Texas A&M Health Science Center College of Medicine in College Station.

The timing is critical, as over the next several decades huge numbers of aging Baby Boomers will develop Alzheimer’s disease and other forms of dementia.

Besides sparing thousands of Americans needless suffering, “if you could reduce that number by 10 percent, your cost savings would be immense,” said William Thies, chief medical and scientific officer for the Alzheimer’s Association in Chicago.

Although experts have long suspected a link between high blood pressure and dementia, without trial data those suspicions inevitably remain hypotheses.

“What we do know is that there’s an association between high blood pressure and a higher rate of dementia — it’s not a large increased risk but there is some increase,” Fine said.

“A whole bunch of epidemiologic data says there’s a link, and one trial actually showed that if you lowered people’s blood pressure it decreased the amount of dementia,” added Thies.

That particular trial used blood pressure drugs known as calcium-channel blockers, one in an extensive armamentarium of medications for the condition. Still, no one really knows why treating high blood pressure would lower the odds of dementia if, in fact, it really does.

“We’d really like to know the answer because it would give us our first confirmed pathway to modifying the amount of dementia by treating people with known agents,” Thies said. “That would be very important.”

The SPRINT trial will randomize participants — all of whom have systolic blood pressure of 130 mm Hg or higher — either to a group taking more intensive drug therapy (three or four medications) to try to get their blood pressure under 120, or a control group taking about two medications to maintain blood pressure at the currently recommended 140.

“We may discover lower blood pressure will not reduce the rate of dementia, but if the lower goal did reduce the rate of dementia by 10 or 20 or 30 percent, that would be an important observation because we don’t have other good treatments for dementia,” Fine said. “SPRINT should provide some additional science to inform us whether lowering blood pressure to the lower goal will, in fact, reduce the rate of developing dementia.”

“There are a lot of reasons why we ought to control blood pressure anyway, but this gives us another very important reason,” Thies added.

SOURCES: Ian Murray, Ph.D., assistant professor, neuroscience and experimental therapeutics, Texas A&M Health Science Center College of Medicine, College Station; Lawrence Fine, M.D., DrPH, chief, clinical applications and prevention branch, division of cardiovascular sciences, U.S. National Heart, Lung, and Blood Institute; William Thies, Ph.D., chief medical and scientific officer, Alzheimer’s Association, Chicago

Soy contains estrogen-like compounds, and researchers have proposed that the amount of soy a woman consumes may influence her risk of having hot flashes and night sweats during menopause. These symptoms are related to the sharp drop in estrogen levels that occurs as women stop menstruating, making it possible that high consumption of estrogen-like compounds could reduce their severity — or eliminate them.

To investigate, Dr. Rafael Bolaños of San Marcos University in Lima, Peru, and colleagues searched the medical literature for clinical trials lasting at least 12 weeks in which soy products were compared with inactive placebo in menopausal women.

The researchers divided the studies into three groups based on the type of supplement used: concentrate of soy isoflavones, the estrogen-like compounds found in soy (3 studies); soy extract (6 studies), or soy dietary supplement (10 studies).

Within each group, women using soy products showed significant improvement of their hot flashes compared to the women on placebo. The extract seemed to have the strongest effects, while soy isoflavones came in second place, and soy dietary supplements came in last.

But because the various studies were so different from one another in terms of dosages used, outcomes measured, and other factors, the researchers say, firm conclusions can’t be drawn from the current analysis.

They call for more studies in which these factors are standardized to better establish whether or not soy is helpful to women with menopausal symptoms.

SOURCE: Menopause.

“Our study indicates that it’s more prevalent than one might have guessed.” said Roland Dunbrack, Jr., co-author of the report, which appears in the March 18 issue of the New England Journal of Medicine.

“It’s an exclusion that in many cases, maybe in most cases, doesn’t need to be used,” said Dunbrack, an associate professor at Fox Chase Cancer Center in Philadelphia.

Review boards, which approve studies at both the local and federal level, already keep a close eye on research that excludes minority groups or either gender, Dunbrack noted. He and his colleagues launched their research because they were curious about study restrictions involving gays and lesbians.

“If you want to exclude a particular group, you usually have to have a rationale for it,” he said, but there aren’t such restrictions for gays and lesbians.

The researchers suspected that the issue of inclusion — or exclusion — of gays and lesbians doesn’t come up very much outside of research into sexuality. And they found that to be the case, at least in asthma research. Of more than a thousand studies on asthma that the researchers located, none had restrictions based on sexual orientation.

However, out of 243 studies that included the words “couple,” “erectile dysfunction” or “hypoactive” (referring to low sex drive), 37 excluded non-heterosexuals in some way.

“It’s not that every study we looked at should be rewritten,” Dunbrack said, but there should be reasons given for the exclusions, and “we don’t know for these studies what these rationales would be.”

Those most likely to restrict people in same-sex relationships were industry sponsored trials, multi-regional studies and phase 3 clinical trials (the phase before drugs are typically submitted for FDA approval), the team found.

James Beaudreau, education and policy director of the Gay and Lesbian Medical Association, said it’s important to include lesbians, gays, bisexuals and transgendered people in medical research because they experience certain medical conditions at different rates.

For example, studies suggest that lesbians may be more likely to develop breast cancer than other women. Also, he said, “the health effects of stress related to living with a stigmatized identity include higher rates of depression, anxiety disorders, suicide attempts, and substance abuse.”

“The real danger is that gay and transgender people may respond differently to medical interventions, but we will never know if we don’t collect the information,” said Beaudreau, whose organization represents medical professionals.

“We don’t believe that it places an undue burden on researchers to ask questions about sexual orientation and gender identity,” he said.

SOURCES: Roland Dunbrack, Jr., Ph.D., associate professor, Program in Molecular and Translational Medicine, Fox Chase Cancer Center, Philadelphia; James Beaudreau, education and policy director, Gay and Lesbian Medical Association, San Francisco; New England Journal of Medicine

“We’ve studied men’s sexual health for many years, and we have not studied women’s sexual health, concerns, issues and problems in the past, and there’s a gender information gap,” said Dr. Irwin Goldstein, editor-in-chief of The Journal of Sexual Medicine, in which this new study was recently published. “This kind of study helps narrow that gap and provide information on the real behavior of real women, and gives us a sense of what to expect.”

Goldstein is director of sexual medicine at Alvarado Hospital in San Diego.

The authors of this new study, out of Lisbon, Portugal, asked 188 women aged 17 to 40 to fill out a questionnaire the day they were discharged from the hospital after the birth of a child.

Almost half (44.7 percent) of women said that their most frequent sexual intercourse took place during the first trimester of the pregnancy. A little more than one third (35.6 percent) said sex was most frequent in the second trimester.

Only 10 percent said that the most frequent sexual activity occurred in the third trimester, while 55 percent said that sex decreased at this point.

But the majority of women — 80.1 percent — said they did have intercourse at this later stage of the pregnancy. And almost 40 percent of women said they had sex during the birth week.

Roughly half of all women said there had been no change in their sex life during the first or second trimesters.

Almost one-quarter (23.4 percent) of women admitted they were afraid that sex would hurt the baby.

In the course of researching her book, The Working Woman’s Pregnancy Book, Dr. Marjorie Greenfield said that this fear sometimes came from the male partner.

“One woman said that she felt like having sex, but her husband was uncomfortable about the idea,” said Greenfield, who is division chief of general obstetrics & gynecology at University Hospitals Case Medical Center in Cleveland. “Some men say they feel the baby is watching them or that they are going to hurt the baby.”

About half of the women in the survey said their sexual satisfaction remained the same throughout the pregnancy while a lesser proportion — 27.7 percent — said it declined. Sexual desire was the same in 38.8 percent and down in 32.5 percent of the participants.

The most common type of sexual activity was vaginal (performed by 98.3 percent), followed by oral sex (38.1 percent) and anal sex (6.6 percent). About one-fifth of women said they masturbated during pregnancy.

More than 40 percent of women said they felt less attractive while they were expecting, but three-quarters said they sensed no decrease in sexual interest from their husband or partner.

In general, the authors and other experts stated, sex during pregnancy is not dangerous.

“A lot of people think it causes abortions in the third trimester or damage to the child, but regular penal-vaginal intercourse is not an issue,” Goldstein said, adding that there can be issues with air embolisms during oral sex and infections during anal sex.

And there are some people for whom sex during pregnancy can be unsafe, said Greenfield, including women with placenta previa, when the placenta lies lower in the uterus.

“Bumping into the placenta under those circumstances can cause the mom to hemorrhage,” she said.

“But for your average person, there’s only one sex act that has an increased risk for women who are pregnant,” she added. “There have been fatalities if air is blown into vagina. Anything that forces air into the vagina is not safe.”

“It’s important to recognize that desire and self-image and variables such as hormonal changes and tiredness and concern for children really affect women’s sexual drives and functions, especially as they go to the third trimester,” Goldstein said. “It’s OK to expect changes in sexual function during the pregnancy.”

SOURCES: Marjorie Greenfield, M.D., division chief, general obstetrics & gynecology, University Hospitals Case Medical Center, Cleveland, and author, The Working Woman’s Pregnancy Book; Irwin Goldstein, M.D., director, sexual medicine, Alvarado Hospital, San Diego, and editor-in-chief, Journal of Sexual Medicine, Journal of Sexual Medicine

This germline mutation of the androgen receptor (AR) may prove to be a genetic biomarker for familial prostate cancer in the black American male population, according to the team at Louisiana State University in New Orleans.

Black American men have a higher incidence of prostate cancer than any other racial group. The small amount of research that’s been done on the role that AR mutations play in prostate cancer has been limited to white men.

This study found a germline AR-A1675T substitution mutation in the DNA-binding domain in three black American men with a family history of early-onset prostate cancer. This mutation may contribute to prostate cancer by “altering the AR DNA-binding affinity and its response to androgens, non-androgenic steroids or anti-androgens,” according to a news release about the study.

The study was published online this week in the Asian Journal of Andrology.

Further research is needed to learn more about the role this mutation plays in prostate cancer in black Americans, the researchers said.

SOURCE: Asian Journal of Andrology

The ability to track MRSA (methicillin-resistant Staphylococcus aureus) can help scientists figure out how the bacteria mutates and spreads so fast. It also could lead to better ways to control the infection as well as other emerging “superbugs,” researchers say.

“This is the first demonstration of a new approach to genome sequencing,” Stephen Bentley, from the Wellcome Trust Sanger Institute in England and senior author of the study, said during a Wednesday teleconference.

“This is set to revolutionize genetic sequencing in general, and, I believe, a particular impact will be seen with bacteria, and more particularly, those bacteria which cause infectious disease,” he said.

The aspect of MRSA that makes it so concerning is that it is resistant to many antibiotics. One theory holds that the bacteria developed in response to the overuse of antibiotics. The current treatment is with an antibiotic called vancomycin, but the fear is that the bacteria could become resistant to this drug, too.

Although MRSA is usually not serious in healthy people, it can cause serious complications, including organ failure and death, if it enters the bloodstream. The presence of MRSA in hospitals is a particularly worrisome occurrence.

The new findings are published in the Jan. 22 issue of Science.

To make their discovery, the researchers used a new method of sequencing DNA, which enabled them to quickly see single mutations in the genetic code of the bacteria and identify differences between closely related strains of MRSA in 62 samples.

“We showed that mutations in MRSA occurred far faster than previously thought,” the study’s co-lead author, Dr. Simon Harris, also from the Sanger Institute, said during the teleconference.

Using the new technology, the researchers were able to see how fast MRSA mutated. In the strain of the bacteria they studied, mutations happened about every six weeks.

To understand how MRSA spreads around the world, the researchers looked at bacteria samples from hospitals in North and South America, Europe, Asia and Australia over a period of more than 20 years.

By tracking changes in the genetics of the bacteria, they were able to develop an “evolutionary tree of MRSA.”

Using this method, they found that one strain of MRSA first developed in Europe in the 1960s about the time antibiotics were starting to be widely used — a finding the researchers said adds credence to the theory that MRSA is a product of the overuse of antibiotics.

In addition, 20 MRSA samples came from one hospital in Thailand. Using those samples, the researchers were able to show how the same MRSA infection was transmitted within the hospital, Harris said.

MRSA is a common infection in hospitals, study co-author Sharon Peacock, a professor of clinical microbiology at the University of Cambridge and Faculty of Tropical Medicine at Mahidol University in Bangkok, said during the teleconference.

“In the U.S., MRSA infections doubled from 127,000 cases in 1999 to 278,000 cases in 2005,” she said. “Also in the U.S., annual deaths increased from 11,000 to 17,000 from MRSA problems in the same time frame.”

Peacock said that the new technology will enable doctors to study MRSA in such fine detail that “it will become possible to determine routes of MRSA transmission in a localized setting, such as a ward or a hospital.”

This could identify “hot spots” of MRSA transmission, which could lead to better infection control, she said.

Dr. Pascal James Imperato, dean of the School of Public Health at the Downstate Medical Center in New York City, said he agreed with the contention that MRSA developed because of the widespread use of antibiotics.

“This research describes the use of a newer technique to characterize the genetics of MRSA strains, to elucidate their evolution and to track their epidemiology worldwide,” Imperato said. “Although it is a useful research tool at present, there are possibilities for its greater use in the future in the contexts of clinical medicine and public health.”

“The results of this study also confirm that the evolution of resistant strains and their spread are primarily driven by antibiotic use,” Imperato said.

SOURCES: Pascal James Imperato, M.D., MPH&TM, dean and distinguished service professor, School of Public Health, Downstate Medical Center, New York City; Jan. 21, 2010, teleconference with Simon Harris, Wellcome Trust Sanger Institute, Cambridge, United Kingdom, Stephen Bentley, Ph.D., Wellcome Trust Sanger Institute; Sharon Peacock, Ph.D., professor of clinical microbiology, University of Cambridge, United Kingdom and Faculty of Tropical Medicine, Mahidol University, Bangkok

In a large study of some 25,000 British adults, researchers failed to find any “significant” differences in cancer risk related to dietary intake of these compounds.

Phytoestrogens are found in a wide range of foods including dairy products, soy foods, cereals, fruits, vegetables, nuts, seeds, coffee and tea. Previous studies have suggested dietary phytoestrogen intake is associated with increased breast cancer risk and reduced colorectal cancer risk in women. The results from earlier studies were hampered, however, by limited data about phytoestrogen content in food.

No previous research has examined the association between phytoestrogen intake and prostate cancer risk.

In the current study, reported in the American Journal of Clinical Nutrition, researchers assigned phytoestrogen values to nearly 11,000 foods following chemical analyses. For the first time, phytoestrogen values were assigned to animal products.

Unlike plants, which themselves contain phytoestrogens, phytoestrogens are generated by the digestion of animal products like meat and dairy products by microbes in the gut, the researchers explain.

Phytoestrogen consumption was estimated for cancer-free adult participants in the European Prospective Investigation into Cancer and Nutrition – Norfolk (EPIC-Norfolk). EPIC-Norfolk participants, recruited between 1993 and 1997, filled out a diet diary for a week and provided information about age, height, weight, smoking, aspirin use, menopausal status, and family history of cancer among other things.

Cancers that developed within 12 months of study recruitment were identified from a cancer registry totaling 244 breast cancers, 221 colorectal cancers, and 204 prostate cancers. The diets and other relevant information from those who developed cancer were compared to information from other participants (controls) who did not develop cancer.

While acknowledging more study is needed, the authors concluded that there is “little evidence” that phytoestrogen intake is “associated with subsequent risk of breast or prostate cancer.”

However, phytoestrogens found in eggs and dairy products “may influence the risk of prostate cancer and colon cancer in women,” they report.

The associations are weak and without further study do not warrant changes in diet, lead investigator Heather Ward, of the MRC Center for Nutrition and Cancer in the Department of Public Health and Primary Care at Strangeways Research Laboratory in Cambridge, England, told Reuters Health.

“The results of the present study do not suggest that anyone should alter their phytoestrogen intake, in part because the majority of the associations between phytoestrogen intake and cancer risk were not significant,” the doctoral candidate wrote in an email.

“It is worth noting that phytoestrogen intake within an Asian-style diet is more than ten-fold greater than in Western diets, without evidence of an increase in cancer risk,” she added.

Because phytoestrogen consumption is on the rise in Britain, the authors urge further monitoring because “the relation between phytoestrogen and cancer may change over time.”