- ALLERGY, RESPIRATORY
- Traffic, Dust Linked to Asthma in Kids
- New Spray Could Benefit Cystic Fibrosis Patients
- Using Music and Sports to Improve Kids' Asthma
- ALTERNATIVE MEDICINE
- Many Cancer Patients Turn to Complementary Medicine
- Regular Yoga May Improve Eating Habits
- Acupuncture May Trigger Natural Painkiller
- BONES & JOINTS
- Soccer's a Winner for Building Bone Health in Girls
- Bone Density Predicts Chances of Breast Cancer
- Vitamin K Doesn't Slow Bone Loss
- CANCER
- Study Suggests Link Between Cell Phones and Brain Tumors
- Smoking Exposure Now Linked to Colon, Breast Cancers
- Red Meat No No No But Oily Fish Yes Yes Yes
- CAREGIVING
- Most Women Struggle With Rising Health Care Costs
- Omega-3 Fatty Acid May Help 'Preemie' Girls' Brains
- With Age Comes Greater Risk of Hypothermia
- CIRCULATORY SYSTEM
- Obesity Linked to Heart Failure Risk
- Review Confirms Links Between Diet, Heart Health
- Migraines in Pregnancy Boost Vascular Risks
- COSMETIC
- What to Do If You Have Unsightly Veins
- With Psoriasis, the Internet May Offer Hope
- New Genetic Links to Baldness Discovered
- DENTAL, ORAL
- A Sweet Way to Shield Baby's Teeth
- Holistic Dentistry-My View
- An Oral Approach to Heart Disease
- DIABETES
- Treatment for Type 2 Diabetes Updated
- Whole Grains Take a Bite Out of Type 2 Diabetes Risk
- Vitamin K Slows Insulin Resistance in Older Men
- DIET, NUTRITION
- Eating Vegan or Raw-Vegan at Regular Restaurants
- Fruits, Vegetables, Teas May Cut Smokers' Cancer Risk
- Vitamin D May Help Keep Aging at Bay
- DISABILITIES
- Review Finds Marijuana May Help MS Patients
- Could Your Cell Phone Help Shield You From Alzheimer's?
- ENVIRONMENTAL HEALTH
- Global Warming May Bring More Respiratory Woes
- Clear Skies Have Become Less So Over Time, Data Show
- Radiation Exposure Linked to Aggressive Thyroid Cancers
- EYE CARE, VISION
- Cases of Age-Related Farsightedness to Soar
- Don't Lose Sight of Halloween Safety
- Eye Problems, Hearing Loss May Be Linked
- FITNESS
- Be Healthy, Spend Less
- Run for Your Life
- After a Stroke, Light Exercise Gets Hands, Arms Working Again
- GASTROINTESTINAL PROBLEMS
- Japanese Herbals May Ease Gastro Woes
- Olive Oil May Protect Against Bowel Disease
- Peppermint Oil, Fiber Can Fight Irritable Bowel
- GENERAL HEALTH
- Time to Remind Teens About Sun Protection
- Eating More Soy May Be Good For Your Lung Function
- Eating Healthy : You Can Live Longer
- HEAD & NECK
- Ski Helmets Encouraged for All
- Zen May Thicken Brain, Thwart Pain
- Many Children Will Outgrow Headaches
- HEALTH & TECHNOLOGY
- Subway Defibrillators Save Lives
- Airport Full Body Scanners Pose No Health Threat: Experts
- E-Mailing Your Way to Healthier Habits
- HEART & CARDIOVASCULAR
- Vigorous Exercise Cuts Stroke Risk for Men, Not Women
- Fewer Heart Attacks After England Goes Smoke-Free
- Ginkgo Won't Prevent Heart Attack, Stroke in Elderly
- INFECTIOUS DISEASE
- Swine Flu Now Reported in All 50 States
- Older Adults May Have Some Immunity to Swine Flu
- Chinese 'Devil Dung' Plant Could Be a Swine Flu Fighter
- KID'S HEALTH
- Folic Acid Reduces Infant Heart Defects
- Teen Internet Addicts More Likely to Self-Harm: Study
- Meaningful Conversations Boost Kids' Language Skills
- MEN'S HEALTH
- Low Vitamin D Levels May Boost Men's Heart Attack Risk
- Eating Fast Until Full Triples Overweight Risk
- Physical Activity May Prolong Survival After Colon Cancer
- MENTAL HEALTH
- Consciousness Helps the Mind and Body Work Together
- Music Soothes Anxiety as Well as Massage Does
- Drink Away Dementia?
- PREGNANCY
- Breast-Feeding Benefits Moms and Babies
- Calcium Supplements Cut Blood Lead Levels During Pregnancy
- Pregnant Women Exposed To Certain Pollutants Could Lower Childs IQ
- SENIORS
- Vitamin D May Help Keep Aging at Bay
- Older People at Greater Risk of Swine Flu Death
- Memory Loss Help from Brain Supplement Prevagen
Antioxidants Blunt Exercise Benefit, Study Shows
By eHolistic.com Published: 05/11/2009
By Steven Reinberg
HealthDay Reporter
MONDAY, May 11 (HealthDay News) -- Exercise helps increase insulin sensitivity and ward off diabetes, but taking supplemental antioxidants such as vitamins C and E actually blunts that benefit, researchers report.
Exercise helps increase the body's sensitivity to insulin by making reactive oxygen species, or "free radicals," which antioxidants work against. These free radicals are thought to damage cells and speed the aging process, but they are also used by the body to prevent cell damage after exercising, the researchers say.
"When you exercise you do improve your insulin sensitivity, and if you are at risk for diabetes improving insulin sensitivity is good," said researcher Dr. C. Ronald Kahn, the Mary K. Iacocca Professor at the Joslin Diabetes Center and Harvard Medical School.
Part of the reason that exercise improves insulin sensitivity is that it causes oxidative stress on the muscles. The muscles respond to this stress by creating free radicals, Kahn said.
"If you take antioxidants like vitamins C and E, you block the oxidative stress response, but you also block the beneficial effects of exercise on insulin sensitivity," he said.
The report is published in this week's online edition of the Proceedings of the National Academy of Sciences.
For the study, Kahn's team looked at the benefit of exercise in increasing insulin resistance in 39 young men, roughly half of whom were taking supplemental vitamins C and E.
Kahn's group found that men taking vitamin supplements had no change in their insulin resistance, but men not taking vitamins had an increase in free radicals, which increases insulin resistance. A month after stopping the vitamin supplements insulin sensitivity was restored, the researchers noted.
"If you are exercising, in part, to reduce diabetes risk, you shouldn't take vitamin C and E, because you are going to block some of the beneficial effect of the exercise to prevent the diabetes," Kahn said.
Dr. David L. Katz, director of the Prevention Research Center at Yale University School of Medicine, thinks this study raises doubts about the benefits of taking antioxidant supplements, but not about the value of these vitamins in the foods people eat.
"We have long held out hope that antioxidant supplements, among them vitamin C, vitamin E, beta carotene, and more recently lycopene and others, would help prevent diseases from the common cold to cancer, heart disease to diabetes," Katz said. "But to date, virtually all of the best research evidence is contrary to this hope."
This study has a counter-intuitive conclusion, namely that antioxidant supplements may actually interfere with the beneficial effects of exercise on insulin sensitivity, Katz said.
"This is a small and short-term study, and thus cannot tell us definitively that antioxidant supplements are harmful in diabetes or the insulin-resistant state that often precedes it. But that is precisely what the study suggests may be true," Katz said.
For now, there is substantial uncertainty about any health benefits and the potential harms of antioxidants as supplements, Katz said. "But we have no such confusion about the powerful health-promoting effects of wholesome, mostly plant-based diets and regular physical activity."
More information
For more information on antioxidants, visit the U.S. National Library of Medicine.
SOURCES: C. Ronald Kahn, M.D., Mary K. Iacocca Professor, Joslin Diabetes Center and Harvard Medical School, Boston; David L. Katz, M.D., M.P.H., director, Prevention Research Center, Yale University School of Medicine, New Haven, Conn.; May 11-15, 2009, Proceedings of the National Academy of Sciences, online
Last Updated: May 11, 2009
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