ALLERGY, RESPIRATORY
Climate Change Could Sting Allergy, Asthma Sufferers
Keep Asthma, Allergies at Bay for the Holidays
Molecule in Skin May Link Eczema and Asthma
ALTERNATIVE MEDICINE
Hypnosis Cuts Hot Flashes for Breast Cancer Survivors
Regular Yoga May Improve Eating Habits
Uncover Why Turmeric Helps You Heal
ANIMAL CARE
Beware of Dog Bites
Separation Anxiety, Canine-Style
Rest Easy. When It Comes to Swine Flu, Your Pet Is Safe
BONES & JOINTS
Fall Sports Peak Time for Lower Leg Damage
Tips to Ease an Aching Back
Returning to the Road Tricky After Injury
CANCER
Study Cites Gains in Gall Bladder Cancer Treatment
Gene Screen May Predict Colon Cancer's Return
Exercise Cuts Lung Cancer Risk in Ex-Smokers by 45%
CAREGIVING
Rapid Infant Weight Gain Linked to Childhood Obesity
Undoing the 'Big Baby' Trend
Most Women Struggle With Rising Health Care Costs
CIRCULATORY SYSTEM
Bye, Bye Back Fat?
Varicose Veins May Mask Larger Problem
Mercury in Fish Linked to High Blood Pressure
COSMETIC
Contact Lenses Boost Kids' Self-Image
Study Evaluates Laser Therapies for Hair Removal
Science May Banish Bad Hair Days
DENTAL, ORAL
Gum Disease Might Boost Cancer Risk
Study Links Osteoporosis Drugs to Jaw Trouble
Health Tip: At Risk for Gingivitis
DIABETES
Patients' Photos Help Boost Radiologists' Accuracy
Strict Blood Sugar Lowering Won't Ease Diabetes Heart Risk
Laughter May Lower Heart Attack Risk in Diabetics
DIET, NUTRITION
Adding Garlic Might Cut Cancer Risk
For Fitness, Cutting Calories May Not Be Enough
Caffeine May Offer Some Skin Cancer Protection
DISABILITIES
Review Finds Marijuana May Help MS Patients
Could Your Cell Phone Help Shield You From Alzheimer's?
ENVIRONMENTAL HEALTH
Stomach Germ May Protect Against Asthma
Topical Drugs May Pollute Waterways
Hurricane Threats: Time to Batten Down the Hatches
EYE CARE, VISION
Vision Test for Young Children Called Unreliable
Florida Vision Test Law: Fewer Traffic Deaths Among Elderly
Kids' Eye Injuries From Golf Clubs Rare But Severe
FITNESS
Exercise Cuts Lung Cancer Risk in Ex-Smokers by 45%
Exercise Extends Life of Kidney Patients
The Juice From Beetroots May Boost Stamina
GASTROINTESTINAL PROBLEMS
New Guidelines Issued for Management of IBS
HRT Use Raises Risk of Stomach Trouble
Olive Oil May Protect Against Bowel Disease
GENERAL HEALTH
Hidden Salt in Diet Haunts Many With Heart Failure
Sun, Smoke, Extra Weight Add Years to Skin
Keep Fire Safety in Mind as You Celebrate
HEAD & NECK
Many Children Will Outgrow Headaches
Zen May Thicken Brain, Thwart Pain
Ski Helmets Encouraged for All
HEALTH & TECHNOLOGY
Subway Defibrillators Save Lives
'Comfort Dogs' Come to Emotional Rescue
Save Your Aging Brain, Try Surfing The Web
HEARING
Summer Sounds Can Lead to Hearing Loss
Noise Hurts Men's Hearing More, Study Shows
HEART & CARDIOVASCULAR
Man's Best Friend Helps Mend Broken Hearts
Quitting Smoking Doubles Survival in Early Stage Lung Cancer
Brown Rice Tied to Better Heart Health in Study
INFECTIOUS DISEASE
Swine Flu Loves a Crowd
Older Adults May Have Some Immunity to Swine Flu
Surgical Masks Could Prevent Flu, Maybe
INFERTILITY
Obesity May Affect Fertility in Young Womene
KID'S HEALTH
Coconut Oil May Help Fight Childhood Pneumonia
Scorpion Anti-Venom Speeds Children's Recovery
Dangerous Toys Still on Store Shelves, Report Finds
MEN'S HEALTH
Strenuous Daily Workout May Keep Cancer at Bay
Vigorous Exercise Cuts Stroke Risk for Men, Not Women
Countdown to Hair Loss
MENTAL HEALTH
Meaningful Conversations Boost Kids' Language Skills
Cinnamon Breaks Up Brain Plaques, May Hold Key to Fighting Alzheimer’s
The Acne Drug Accutane More Than Doubles Depression Risk
PAIN
Alleviating Rheumatoid Arthritis
Are We Exercising Pain Away? Not So Much.
Acupuncture, Real or Fake, Eases Back Pain
PHYSICAL THERAPY
PREGNANCY
Alternative Treatments May Boost IVF Success
Obesity May Affect Fertility in Young Womene
Before Conceiving, Take Folic Acid for One Full Year
SENIORS
The Healthy Habits of Centenarians
Healthy Diet Could Cut Alzheimer's Disease Risk
Could Your Cell Phone Help Shield You From Alzheimer's?
SEXUAL HEALTH
SLEEP DISORDERS
Lose Weight, Sleep Apnea May Improve
Pay Attention to Signs That Say You're Too Fatigued to Drive
Exercising Throat Muscles May Relieve Sleep Apnea
WOMEN'S HEALTH
Supplements Might Reduce Breast Cancer Risk
Caffeine in Pregnancy Associated With Low Birth Weight Risk
Vitamin D Good for Breast Cancer Patients
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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