ALLERGY, RESPIRATORY
Climate Change Could Sting Allergy, Asthma Sufferers
Combating Myths About Seasonal Allergies
Using Music and Sports to Improve Kids' Asthma
ALTERNATIVE MEDICINE
Indian Spice May Thwart Liver Damage
Taking the Mystery Out of Hypnotherapy
Green Tea May Help Brain Cope With Sleep Disorders
ANIMAL CARE
'Comfort Dogs' Come to Emotional Rescue
Beware of Dog Bites
Separation Anxiety, Canine-Style
BONES & JOINTS
Fall Sports Peak Time for Lower Leg Damage
High Birth Weight Doubles Risk of Rheumatoid Arthritis
Postmenopausal Women With Breast Cancer Face Joint Issues
CANCER
Tanning Beds Shown To Raise Cancer Risk, Study Says
Study Suggests Link Between Cell Phones and Brain Tumors
Yoga May Bring Calm to Breast Cancer Treatment
CAREGIVING
For Dialysis Patients, More Pills = Lower Quality of Life
Omega-3 Fatty Acid May Help 'Preemie' Girls' Brains
Are Hospital Mobile Phones Dialing Up Superbugs?
CIRCULATORY SYSTEM
Common Antioxidant Might Slow Parkinson's
Exercise Extends Life of Kidney Patients
Tai Chi and Qigong Offer Many Health Benefits: Review
COSMETIC
New Genetic Links to Baldness Discovered
Contact Lenses Boost Kids' Self-Image
With Psoriasis, the Internet May Offer Hope
DENTAL, ORAL
Obesity Boosts Gum Disease Risk
Gum Disease May Reactivate AIDS Virus
Scientists Find Gene for Tooth Enamel
DIABETES
Formula Puts Doctor, Patient Glucose Readings on Same Page
Patients' Photos Help Boost Radiologists' Accuracy
Fructose-Sweetened Drinks Up Metabolic Syndrome Risk
DIET, NUTRITION
Imagine Food Aromas That Prevent Overeating
B Vitamins Might Lower Stroke Risk
Brown Rice Tied to Better Heart Health in Study
DISABILITIES
Review Finds Marijuana May Help MS Patients
Could Your Cell Phone Help Shield You From Alzheimer's?
ENVIRONMENTAL HEALTH
Home Renovations by Affluent Families Can Unleash Lead Threat
Radiation Exposure Linked to Aggressive Thyroid Cancers
Green Areas Lower Health Inequities Between Rich, Poor
EYE CARE, VISION
Eye Disease, Cognitive Decline Linked in Study
Kids Who Spend More Time Outdoors Have Better Vision
Glaucoma Treatment Can Prevent Blindness
FITNESS
Exercise 30 Minutes a Day? Who Knew!
Football Can Shrink Players
Exercise Cuts Lung Cancer Risk in Ex-Smokers by 45%
GASTROINTESTINAL PROBLEMS
Peppermint Oil, Fiber Can Fight Irritable Bowel
Gum Chewing May Speed Colon Surgery Recovery
New Yogurt May Ease Stomach Ulcers
GENERAL HEALTH
Most Women Struggle With Rising Health Care Costs
Maximize Your Run
Eat Light - Live Longer
HEAD & NECK
Zen May Thicken Brain, Thwart Pain
Ski Helmets Encouraged for All
Many Children Will Outgrow Headaches
HEALTH & TECHNOLOGY
'Cell Phone Elbow' -- A New Ill for the Wired Age
'Comfort Dogs' Come to Emotional Rescue
Airport Full Body Scanners Pose No Health Threat: Experts
HEARING
Summer Sounds Can Lead to Hearing Loss
Noise Hurts Men's Hearing More, Study Shows
HEART & CARDIOVASCULAR
Coffee Is Generally Heart-Friendly
Lack of Vitamin D Linked to High Blood Pressure
Omega-3, Some Omega-6 Fatty Acids Boost Cardiovascular Health
INFECTIOUS DISEASE
Chinese 'Devil Dung' Plant Could Be a Swine Flu Fighter
Bacterial Infections May Succumb to Honey
Surgical Masks Could Prevent Flu, Maybe
INFERTILITY
Obesity May Affect Fertility in Young Womene
KID'S HEALTH
Breast-Feeding May Protect a Woman's Heart
Mom's Extra Pregnancy Pounds May Raise Child's Heart Risks
Coconut Oil May Help Fight Childhood Pneumonia
MEN'S HEALTH
Low Vitamin D Levels May Boost Men's Heart Attack Risk
The Dark Side of Vegetarianism
Could Chinese Herb Be a Natural Viagra?
MENTAL HEALTH
Music Soothes Anxiety as Well as Massage Does
Cinnamon Breaks Up Brain Plaques, May Hold Key to Fighting Alzheimer’s
Memory Loss Help from Brain Supplement Prevagen
PAIN
Tai Chi May Help Ease Fibromyalgia
'Cell Phone Elbow' -- A New Ill for the Wired Age
Alleviating Rheumatoid Arthritis
PHYSICAL THERAPY
PREGNANCY
Sleeping Could Help Women Lose The Baby Fat
Heart Defects in Newborns Linked to Antidepressants
Music of Mozart Soothes the Preemie Baby
SENIORS
For Older Walkers, Faster Is Better
Mediterranean Diet Plus Exercise Lowers Alzheimer's Risk
Vitamin D May Help Keep Aging at Bay
SEXUAL HEALTH
SLEEP DISORDERS
Better Sleep, Grades Seem to Go Up
Daylight Savings: Not a Bright Time for All
Moderate Aerobics May Ease Insomnia Symptoms
WOMEN'S HEALTH
Heart Defects in Newborns Linked to Antidepressants
Omega-3 May Reduce Endometriosis Risk
Calcium Helps Ward Off Colon Cancer
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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