ALLERGY, RESPIRATORY
Asthmatics Who Quit Smoking May Reverse Lung Damage
Combating Myths About Seasonal Allergies
Herbal Remedy Could Halt Peanut Allergy
ALTERNATIVE MEDICINE
Fish Oil's Benefits Remain Elusive
Should Your Child Be Seeing a Chiropractor?
Grapefruit Compound Inhibits Hepatitis C Virus
ANIMAL CARE
Safe Toys for Dogs
Rest Easy. When It Comes to Swine Flu, Your Pet Is Safe
Separation Anxiety, Canine-Style
BONES & JOINTS
A Winning Strategy to Beat Spring Sporting Injuries
'Snowbirds' Beware the Climate Changes
Studies Struggle to Gauge Glucosamine's Worth
CANCER
Omega-3 May Safely Treat Precancerous Bowel Polyps
Minorities Distrust Medical System More
Occaisonal Dieting May Cut Breast Cancer, Study Says
CAREGIVING
Exercise During Pregnancy May Help Baby
Bariatric Surgery Centers Don't Deliver Better Outcomes
Moms Who Breast-Feed Less Likely to Neglect Child
CIRCULATORY SYSTEM
Anemia Rates Down for U.S. Women and Children
An Apple a Day May Help Keep Heart Disease Away
Migraines in Pregnancy Boost Vascular Risks
COSMETIC
Mouse Study Finds Molecule That Tells Hair to Grow
The Acne Drug Accutane More Than Doubles Depression Risk
Health Tip: After Liposuction
DENTAL, ORAL
Acupuncture May Ease Anxiety Over Dental Work
Toothbrushing May Stave Off Heart Woes
Obesity Boosts Gum Disease Risk
DIABETES
Brown Rice Bests White for Diabetes Prevention
Findings Challenge Tight Glucose Control for Critically Ill Patients
Diabetes Linked to Cognitive Problems
DIET, NUTRITION
Coffee Drinking Lowers Women's Stroke Risk
The Best Diet? That Depends on You
Even in 'Last Supper,' Portion Sizes Have Grown
DISABILITIES
Review Finds Marijuana May Help MS Patients
Could Your Cell Phone Help Shield You From Alzheimer's?
ENVIRONMENTAL HEALTH
Radiation Exposure Linked to Aggressive Thyroid Cancers
Lead Exposure in Childhood Linked to Criminal Behavior Later
Clear Skies Have Become Less So Over Time, Data Show
EYE CARE, VISION
When Corks Fly, Watch the Eyes
Contact Lens Cases Often Contaminated
Autistic Children Make Limited Eye Contact
FITNESS
Any Exercise Good After a Heart Attack
Resistance Training Boosts Mobility in Knee Arthritis Patients
Walk Long, Slow and Often to Help the Heart
GASTROINTESTINAL PROBLEMS
Soothing Imagery May Help Rid Some Kids of Stomach Pain
New Guidelines Issued for Management of IBS
New Yogurt May Ease Stomach Ulcers
GENERAL HEALTH
Vitamin D Best Taken With Largest Meal of Day, Study Finds
Want Better Health in the New Year, Add Exercise to Your Day
The Juice From Beetroots May Boost Stamina
HEAD & NECK
Ski Helmets Encouraged for All
Zen May Thicken Brain, Thwart Pain
Many Children Will Outgrow Headaches
HEALTH & TECHNOLOGY
Airport Full Body Scanners Pose No Health Threat: Experts
Using Light Therapy to Silence Harmful Brain Activity
Subway Defibrillators Save Lives
HEARING
Noise Hurts Men's Hearing More, Study Shows
Summer Sounds Can Lead to Hearing Loss
HEART & CARDIOVASCULAR
Psychiatric Drugs Might Raise Cardiac Death Risk
Too Much Red Meat May Shorten Life Span
After a Stroke, Light Exercise Gets Hands, Arms Working Again
INFECTIOUS DISEASE
Viral Infection Might Trigger High Blood Pressure
Poor Restroom Cleaning Causes Cruise-Ship Sickness
Swine Flu Is Now a Pandemic Says W.H.O.
INFERTILITY
Obesity May Affect Fertility in Young Womene
KID'S HEALTH
Plastics Chemical Tied to Aggression in Young Girls
Obesity May Raise Kids' Allergy Risk
Daily Exercise at School Yields Rewards
MEN'S HEALTH
Soy Linked to Low Sperm Count
Noise Hurts Men's Hearing More, Study Shows
Physical Activity May Prolong Survival After Colon Cancer
MENTAL HEALTH
Memory Loss Help from Brain Supplement Prevagen
Estrogen May Help Men's Hearts
Living Alone Increases Odds of Developing Dementia
PAIN
'Cell Phone Elbow' -- A New Ill for the Wired Age
Acupuncture, Real or Fake, Eases Back Pain
Alleviating Rheumatoid Arthritis
PHYSICAL THERAPY
PREGNANCY
Placebo Acupuncture Tied to Higher IVF Pregnancies
Obesity May Affect Fertility in Young Womene
Sleeping Could Help Women Lose The Baby Fat
SENIORS
Friends, Not Grandkids, Key to Happy Retirement
A Little Alcohol May Stave Off Alzheimer's
Common Antioxidant Might Slow Parkinson's
SEXUAL HEALTH
SLEEP DISORDERS
Exercising Throat Muscles May Relieve Sleep Apnea
Meditation May Help Put Primary Insomnia to Bed
Pay Attention to Signs That Say You're Too Fatigued to Drive
WOMEN'S HEALTH
Air Pollution Slows Women's Marathon Times
Women Smokers Lose 14.5 Years Off Life Span
Being Active an Hour a Day Puts Brakes on Weight Gain
Add your Article

Soy Linked to Low Sperm Count

By Steven Reinberg
HealthDay Reporter

WEDNESDAY, July 23 (HealthDay News) -- Eating half a serving of soy food a day lowers sperm concentrations and may play a role in male infertility, particularly in obese men, Harvard University researchers report.

The reason for this relationship between soy and sperm count isn't clear. However, researchers speculate that soy increases estrogen activity, which may have a negative affect on sperm production and also interfere with other hormonal signals.

"There have been a lot of interest in estrogen and isoflavones in particular and a potential relationship to fertility and other reproductive disorders," said lead researcher Dr. Jorge Chavarro, a research fellow in the department of nutrition at the Harvard School of Public Health.

Research in animals has shown that isoflavones and estrogen can have a potentially negative affect on reproduction, including decreased fertility, Chavarro said. However, there is very little evidence of how these findings apply to humans, he said.

The new research, he added, lends support to how results of animal studies apply to humans. But Chavarro considers the findings preliminary and inconclusive. "It's way too early to say stop eating soy foods," he said. "It's not time to worry about whether you're eating too much soy. There's not enough information to conclusively say that. "

His report was published in the July 24 online edition of the journal Human Reproduction.

For the study, Chavarro and colleagues collected data on 99 men who attended a fertility clinic for evaluation. The men were asked about how much of 15 soy-based foods they ate in the past three months.

The foods men were asked about included tofu, tempeh, tofu or soy sausages, bacon, burgers, soy milk, cheese, yogurt, ice cream and other soy products like roasted nuts and energy bars.

Because different foods have different levels of isoflavones, half a serving of soy is equal to about one cup of soy milk or one serving of tofu or soy burgers every other day, Chavarro noted.

Chavarro's team found that men who ate the most soy had 41 million fewer sperm per milliliter of semen compared with men who did not eat soy foods. Normal sperm counts range between 80 million and 120 million per milliliter, according to a press release from the journal, a monthly publication of the European Society for Human Reproduction and Embryology.

In addition, the researchers found that the link between soy and sperm concentration was stronger among overweight and obese men. Overweight and obese men produce more estrogen than thinner men, and soy may increase those estrogen levels even further, they speculated.

Moreover, the link between soy and sperm concentration was strongest in men with higher sperm concentrations. Men who have normal or high sperm counts may be more susceptible to soy foods than men with low sperm counts, Chavarro said.

Infertility expert Dr. Hossein Sadeghi-Nejad, an associate professor of urology at UMDNJ New Jersey Medical School and Hackensack University Medical Center, agreed that soy may be one factor affecting fertility, especially in overweight and obese men.

"When patients are overweight, the fat tissue converts male hormones to more female hormones," Sadeghi-Nejad said. "So, it is possible that the combination of this estrogenic source [soy] and the extra internal estrogen that is caused by the conversion of androgen to estrogen through the fat has a more deleterious effect in that group of patients."

In addition, Sadeghi-Nejad noted that although sperm counts decreased most among men who have the highest counts, that should not affect fertility, since sperm counts were still in the normal range.

"But this is a good reminder that if you have an overweight patient, with abnormal semen parameters, and a very high soy intake, it may be wise for them to decrease this factor," Sadeghi-Nejad said.

More information

For more about obesity and infertility, visit the Obesity Action Coalition.



SOURCES: Jorge Chavarro, M.D., Sc.D., research fellow, department of nutrition, Harvard School of Public Health, Boston; Hossein Sadeghi-Nejad, M.D., associate professor of urology, UMDNJ New Jersey Medical School, Hackensack University Medical Center; July 24, 2008, online edition, Human Reproduction

Last Updated: July 24, 2008

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