Vitamins C. E may block exercise benefit

[Susan4]

Hmmmm.....interesting!

http://www.upi.com/Health_News/2009/...4541242247627/

BOSTON, May 13 (UPI) -- Taking antioxidants such as vitamins C and E may nullify the benefit of exercise to reduce the risk of diabetes, U.S. researchers suggest.

Dr. C. Ronald Kahn of the Joslin Diabetes Center and Harvard Medical School in Boston says that part of the reason that exercise improves insulin sensitivity is that it causes oxidative stress on the muscles, HealthDay reported.

Insulin resistance occurs when the cells of the body become resistant to the effects of insulin increasing blood sugar and diabetes risk.

"If you take anti-oxidants like vitamins C and E, you block the oxidative stress response, but you also block the beneficial effects of exercise on insulin sensitivity," Kahn said.

Kahn's team looked at the benefit of exercise in increasing insulin resistance in 39 young men -- roughly half took supplemental vitamins C and E.

The study, published in the online edition of the Proceedings of the National Academy of Sciences, found the men taking the vitamins had no change in their insulin resistance and almost no activation of the body's natural defense mechanism against oxidative damage.

"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 told HealthDay.

[Sonny]

Hi Susan4, came across this article today and I remembered this thread. Thought it was interesting,


http://www.ncbi.nlm.nih.gov/pubmed/16337874
1: Free Radical Biol Med. 2006 Jan 1;40(1):3-12. Links

Exercise training and the antioxidant alpha-lipoic acid in the treatment of insulin resistance and type 2 diabetes.

Henriksen EJ.
Department of Physiology, Muscle Metabolism Laboratory, University of Arizona College of Medicine, P.O. Box 210093, Tucson, AZ 85721-0093, USA. ejhenrik@u.arizona.edu

One hallmark of the insulin-resistant state of prediabetes and overt type 2 diabetes is an impaired ability of insulin to activate glucose transport in skeletal muscle, due to defects in IRS-1-dependent signaling.

An emerging body of evidence indicates that one potential factor in the multifactorial etiology of skeletal muscle insulin resistance is oxidative stress, an imbalance between the cellular exposure to an oxidant stress and the cellular antioxidant defenses.

Exposure of skeletal muscle to an oxidant stress leads to impaired insulin signaling and subsequently to reduced glucose transport activity. Numerous studies have demonstrated that treatment of insulin-resistant animals and type 2 diabetic humans with antioxidants, including alpha-lipoic acid (ALA), is associated with improvements in skeletal muscle glucose transport activity and whole-body glucose tolerance.

An additional intervention that is effective in ameliorating the skeletal muscle insulin resistance of prediabetes and type 2 diabetes is endurance exercise training.

Recent investigations have demonstrated that the combination of exercise training and antioxidant treatment using ALA in an animal model of obesity-associated insulin resistance provides a unique interactive effect resulting in a greater improvement in insulin action on skeletal muscle glucose transport than either intervention individually.

Moreover, this interactive effect of exercise training and ALA is due in part to improvements inIRS-1-dependent insulin signaling.

These studies highlight the effectiveness of combining endurance exercise training and antioxidants in beneficially modulating the molecular defects in insulin action observed in insulin-resistant skeletal muscle.

!
edit to fix bad link.

[Susan4]

So the oxidization stress response is involved in diabetes malfunctions in muscle....but one study says it helps and the other says no it hinders? So one study say no to antiox supps and the other says yes....

Hmm.

Raises another issue of reading too many limited variable studies about all things health, nutrition, food and disease Conflicting answers

[Jishuku]

All I know is, for me, the effect of Vitamin C on exercise results seem to depend on dosage, and possibly synergistic effects with other nutrients..

If I take a supplement, often dosed at 1 gram, I seem to get worse results.... but if I eat 2 oranges (one before, and one after the workout) I seem to get better results than not taking any Vit. C at all.

[Mousehound]

After reading this article, I think I would choose to take the vitamines.
http://thisbluemarble.com/showthread.php?t=15020

[Renegade]

In light of my experience with C and common sicknesses, I'd take the C and deal with the exercise issue...