Navigation Links
Antioxidants Blunt Exercise Benefit, Study Shows
Date:5/11/2009

Vitamins C, E block creation of free radicals that promote insulin sensitivity, researchers say,,,,

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


'/>"/>
Copyright©2009 ScoutNews,LLC.
All rights reserved  

Related medicine news :

1. Brooke Shields and the Makers of COPPERTONE(R) Join Together to Launch COPPERTONE(R) NutraShield(TM) - New Sunscreen Contains Antioxidants That Promote Natural Skin Repair
2. Antioxidants offer pain relief in patients with chronic pancreatitis
3. Coromega Unveils New Healthy Heart and CoQ10 Supplements : Revolutionary Omega-3 Supplement Company Introduces Two Fresh Takes on Heart Health and Antioxidants
4. Too Much Sun, Too Few Antioxidants Spell Eye Trouble
5. Cancer Patients Should Steer Clear of Antioxidants
6. Dr. William S. Gruss, M.D., Says That Medical Research Shows You Can Reduce Your Risk of Cancer By Up To 77% and Reverse the Effects of Aging in A CARDIOLOGISTS GUIDE TO ... ANTI-AGING, ANTIOXIDANTS & RESVERATROL
7. Alimera Sciences Signs Second Agreement With Emory University for Potential Treatments Using New Class of Antioxidants
8. Citrus Juice Gives Boost to Green Tea Antioxidants
9. Natural Antioxidants Help Reduce Oxidative Stress in Diabetes Treatment
10. Citrus juice, vitamin C give staying power to green tea antioxidants
11. Antioxidants do not prevent degenerative eye disease
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Antioxidants Blunt Exercise Benefit, Study Shows
(Date:2/5/2016)... ... February 05, 2016 , ... Freed-Hardeman University President Joe A. ... a joint enrollment and degree completion agreement. The agreement, which begins with ... at FHU|Dickson. , The agreement allows students to be jointly admitted to ...
(Date:2/5/2016)... ... February 05, 2016 , ... In the fourth quarter of ... at the La Valencia Hotel in San Diego, California to discuss changes in ... year’s most outstanding franchise, walking away with the coveted David Wright Award of ...
(Date:2/5/2016)... (PRWEB) , ... February 05, 2016 , ... Boar’s Head ... just in time for this weekend’s Big Game. Take the stress out of your ... will keep your guests happy at every stage of the game. , “The key ...
(Date:2/5/2016)... ... 05, 2016 , ... Stuart Bentkover, MD, FACS is thrilled to ... the most effective tattoo removal today, Dr. Bentkover is the only doctor in Central ... the PicoSure has been approved by the Food and Drug Administration (FDA) as a ...
(Date:2/5/2016)... ... February 05, 2016 , ... Health and wellness is a topic that ... the event they are experiencing an illness. Migraines are a severe form of a ... with migraines would not wish the pain on their worst enemy, the feeling can ...
Breaking Medicine News(10 mins):
(Date:2/5/2016)... 5, 2016 --> ... report "Fetal (Labor & Delivery) and Neonatal Care Equipment ... Pulse Oximeter, Phototherapy/Jaundice Management Devices, CPAP, Capnograph, & Resuscitator) ... report studies the global market over the forecast period ... USD 6.28 Billion in 2015 and is poised to ...
(Date:2/4/2016)... For hospitals considering enrollment in the Federal ... the program, the Health Resources and Services Administration,s (HRSA) ... Mega-Guidance , could have significant impact on plans and ... 2016. Essential Insights , Daniel Neal, ... the Mega-Guidance,s key proposed changes, including a new requirement ...
(Date:2/4/2016)... , Feb. 4, 2016  SciClone Pharmaceuticals, Inc. ... it has entered into a settlement agreement with ... fully resolving the SEC,s investigation into possible violations ... the terms of the settlement agreement, SciClone has ... including disgorgement, pre-judgment interest and a penalty.  This ...
Breaking Medicine Technology: