ALLERGY, RESPIRATORY
Air Pollution May Raise Blood Pressure
Folic Acid Might Offer Allergy Relief
Using Music and Sports to Improve Kids' Asthma
ALTERNATIVE MEDICINE
Licorice May Block Absorption of Organ Transplant Drug
The Zen Way to Pain Relief
U.S. Spends Billions On Alternative Medicine
ANIMAL CARE
Safe Toys for Dogs
Separation Anxiety, Canine-Style
Animals Respond to Acupuncture's Healing Touch
BONES & JOINTS
Yoga Can Ease Lower Back Pain
More Faces Being Spared in Motor Vehicle Accidents
Chronic Low Back Pain Is on the Rise
CANCER
Study Suggests Link Between Cell Phones and Brain Tumors
Ginger Can Ease Nausea From Chemotherapy Treatments
Steady Weight Gain Boosts Late-Life Breast Cancer Risk
CAREGIVING
Baby's Sleep Position May Not Affect Severity of Head Flattening
Tainted China Formula Caused High Rate of Kidney Stones in Kids
Weekend Admission May Be Riskier for GI Bleeding
CIRCULATORY SYSTEM
Review Confirms Links Between Diet, Heart Health
Obesity Linked to Heart Failure Risk
Smog Tougher on the Obese
COSMETIC
The Acne Drug Accutane More Than Doubles Depression Risk
With Psoriasis, the Internet May Offer Hope
What to Do If You Have Unsightly Veins
DENTAL, ORAL
Periodontal Disease Impacts Whole Health
Mom's Vitamin D Levels Affect Baby's Dental Health
Holistic Dentistry-My View
DIABETES
'Standard' Glucose Test May Be Wrong One for Obese Children
Findings Challenge Tight Glucose Control for Critically Ill Patients
Abnormal Heart Rhythm Boosts Death Risk for Diabetics
DIET, NUTRITION
Want to Stop Cancer? You Can, Experts Say
Mediterranean Diet Enriched With Nuts Cuts Heart Risks
Coffee or Tea Consumption May Lower Stroke Risk
DISABILITIES
Review Finds Marijuana May Help MS Patients
Could Your Cell Phone Help Shield You From Alzheimer's?
ENVIRONMENTAL HEALTH
Lead Exposure in Childhood Linked to Criminal Behavior Later
Gas Cooking Might Up Your Cancer Risk
Meat-Eating Dinosaurs Used Legs and Arms Like Birds
EYE CARE, VISION
Cases of Age-Related Farsightedness to Soar
Don't Lose Sight of Halloween Safety
Certain Diabetes Drugs May Pose Eye Risk
FITNESS
Walking Golf Course Affects Swing, Performance
Fall Cleanup Is a Prime Time for Accidents
As Temperature Plummets, It's Still Safe to Exercise
GASTROINTESTINAL PROBLEMS
Gum Chewing May Speed Colon Surgery Recovery
New Yogurt May Ease Stomach Ulcers
HRT Use Raises Risk of Stomach Trouble
GENERAL HEALTH
The Yearly Flu Shot Debate
Natural Oils Help Lower Body Fat For Some
The Brain Comes Alive With the Sounds of Music
HEAD & NECK
Ski Helmets Encouraged for All
Many Children Will Outgrow Headaches
Zen May Thicken Brain, Thwart Pain
HEALTH & TECHNOLOGY
Magnet Therapy May Ease Hard-to-Treat Depression
The Internet Is Becoming One-Stop Shopping for Health Help
Imaging Sheds Light on How Acupuncture Works
HEARING
Summer Sounds Can Lead to Hearing Loss
Noise Hurts Men's Hearing More, Study Shows
HEART & CARDIOVASCULAR
Vigorous Exercise Cuts Stroke Risk for Men, Not Women
Boosting Vitamin D Can Do a Heart Good
Shedding Light on Why Omega-3 Fatty Acids May Help the Heart
INFECTIOUS DISEASE
Swine Flu Closes Three Schools in NYC
Swine Flu Loves a Crowd
Older Adults May Have Some Immunity to Swine Flu
INFERTILITY
Obesity May Affect Fertility in Young Womene
KID'S HEALTH
Green Tea May Help Brain Cope With Sleep Disorders
Fussy Babys Could Be Out Of Your Control
School Meals Need to Get Healthier
MEN'S HEALTH
Low Iron Levels Cut Cancer Risk in Men With PAD
Physical Activity May Prolong Survival After Colon Cancer
Countdown to Hair Loss
MENTAL HEALTH
Love Hormone May Ease Discussion of Painful Topics
Estrogen May Help Men's Hearts
Optimism May Boost Immune System
PAIN
Alleviating Rheumatoid Arthritis
'Cell Phone Elbow' -- A New Ill for the Wired Age
Tai Chi May Help Ease Fibromyalgia
PHYSICAL THERAPY
PREGNANCY
Expectant Mom's Exercise Keeps Newborn's Birth Weight Down
For Baby and Mom Alike, Breast-Feeding May Be Best
Obesity May Affect Fertility in Young Womene
SENIORS
Vitamin D May Help Keep Aging at Bay
More Whole Grains May Mean Less Fat
High-Impact Activity May Be Good for Old Bones
SEXUAL HEALTH
SLEEP DISORDERS
Sleeping Could Help Women Lose The Baby Fat
Pay Attention to Signs That Say You're Too Fatigued to Drive
Lose Weight, Sleep Apnea May Improve
WOMEN'S HEALTH
Bitter Melon Extract May Slow, Stop Breast Cancer
Spice Compounds May Stem Tumor Growth
Prenatal Stress May Boost Baby's Asthma Risk
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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