Vitamins & Exercise: Two Viewpoints

[Islander]

First, let's see what the BBC has to report:

Vitamins 'undo exercise efforts'

Taking vitamins after exercise may undo some of the beneficial effects of the workout, research suggests.
Some advocate taking antioxidants like vitamin C and E to help protect the body from harmful chemical by-products it creates in breaking into a sweat.

But German scientists now believe these "free radicals" may actually be good for us and even buffer against diabetes, PNAS reports.
And mopping them up with antioxidants may do more harm than good.

It is thought that antioxidant vitamins may be able to prevent damage to the body's tissues called "oxidative stress" by eliminating the free radicals which are said to cause it.
This damage has been implicated in several major diseases including cancer and heart disease as well as normal ageing.
But Dr Michael Ristow, of the University of Jena, and his team have shown free radicals may have a positive effect on the body by increasing its sensitivity to insulin - something that is lost in type 2 diabetes.
And this effect is blocked by antioxidant vitamins.
Too much of a good thing
Men who took vitamin C and E supplements showed no changes in their free radical levels, whereas those who did not take these antioxidants showed increased levels of free radical oxidative stress.
After four weeks of intensive exercise training, insulin sensitivity was restored only in the group of men who did not take antioxidant supplements.
The men who took the vitamin supplements fared worse, metabolically.
Dr Sarah Aldred, a lecturer in exercise biochemistry at the School of Sport and Exercise Sciences at the University of Birmingham, said: "It doesn't mean that antioxidants like vitamin C and vitamin E are bad for us, it just means that sometimes we need to consider whether taking supplements is actually beneficial.
"As this study shows it is not actually always the case."
Dr Elisabeth Weichselbaum of the British Nutrition Foundation said: "Antioxidants protect the cells in your body from damage and therefore help to reduce the risk of certain diseases such as cancer.
"But you should not consume high doses on a regular basis as this can have negative effects on your body.
"If you stick to a healthy and varied diet, you generally get enough of the nutrients you need and you don't run the risk of consuming large amounts that may be harmful for you."

http://news.bbc.co.uk/2/hi/health/8043456.stm


And now, another viewpoint:

Antioxidants may ‘block’ benefits of exercise: Study

By Stephen Daniells, 12-May-2009

Supplements of antioxidant vitamins after exercise may decrease the benefits of the workout by blocking the positive effects of reactive oxygen, says a new study.

Researchers from Germany and the US report in the Proceedings of the National Academy of Sciences that a combination of 1,000 mg per day of vitamin C and 400 IU per day of vitamin E adversely affected insulin sensitivity, and thereby increase the risk of type 2 diabetes.

Participants, both trained and untrained, underwent 85 minutes of exercise five days per week for four weeks.

“Based on the evidence derived from the current study, we here propose an essential role for exercise-induced reactive oxygen species formation in promoting insulin sensitivity in humans,” wrote the researchers from the University of Jena, German Institute of Human Nutrition, University of Leipzig, and Harvard Medical School.

“Most importantly, […] changes in gene expression and the increase in insulin sensitivity following physical exercise are almost completely abrogated by daily ingestion of the commonly used antioxidants vitamin C and vitamin E.

“Thus, antioxidant supplementation blocks many of the beneficial effects of exercise on metabolism,” they added.

Questions
The study has been questioned by antioxidant expert Alexander Schauss, PhD, from AIBMR Life Sciences, a nutraceutical products consultancy (click here for Dr Schauss’ full reaction).

Dr Schauss told NutraIngredients.com: “I would never put an “untrained” person, no matter what their BMI or age, into a program that requires 85 minutes of exercise 5 days per week for 4-weeks, as required in this study. The body needs to accommodate an increase in physical activity to build up its endogenous antioxidant defences to the anticipated increase in ROS.

“Athletic clubs that sell memberships have long realized that individuals who sign up and begin at an intense level of exercise can feel defeated due to the side effects they experience in the first month and for this reason often stop their exercise program and revert to a more sedentary lifestyle.

“I have to question the design of the study in light of this and many similar known factors related to exercise,” he added.

Useful, useless, or harmful?
Lead author Michael Ristow told NutraIngredients.com that a number of studies have already shown that antioxidant supplements have no benefit, and his new study suggests that “such supplements may be harmful in regards to glucose metabolism and endogenous ROS defense capacity”.

“A significant number of studies have shown that fruits and vegetables promote health, while antioxidant supplements do not. This insinuates that fruits and vegetables are healthy despite their content in antioxidants, and that other compound contained within these are responsible for these health-promoting effects of fruits and vegetables,” he added.

Ristow and his co-workers note that the new study “applied comparably high doses of oral antioxidants, which have been tested in healthy young men only”.

Study details
Ristow and his co-workers recruited 19 untrained and 20 pre-trained healthy young men, and randomly assigned them to receive either a combination of vitamin C and vitamin E, or placebo, during four weeks of physical exercise (85 minutes of exercise five days per week).

At the end of the study, the researchers found that consumption of antioxidant supplements showed no changes in their ROS levels, while the control group experienced increases in the formation of the free radicals.

Insulin sensitivity was only restored in the control group, and not in the antioxidant group, said the researchers.

“If transient increases in oxidative stress are capable of counteracting insulin resistance in humans, it is possible that preventing the formation of ROS by, for example, antioxidants might actually increase, rather than decrease, the risk of type 2 diabetes,” wrote the researchers. “This remains to be determined,” they added.

Reaction
Commenting on the science, Dr Schauss told NutraIngredients.com that he would be surprised to learn that an exercise trainer would advocate such an intense training programme, and limit the supplementation routine to daily intake of 1000 mg of Vitamin C and 400 IU of vitamin E.

“There are far more nutrients and phytochemicals found in the diet and available supplements and antioxidant-rich foods and juices that would be needed to anticipate the degree of oxidative stress an individual would experience with such an exercise program,” he said.

Headlines
“This paper does NOT deserve media attention for many reasons,” said Dr Schauss. “[It certainly does not deserve] headline news that might discourage the use of vitamin C and/or E by individuals engaged in exercise routines, or those contemplating exercise.”

The study has already achieved headlines, however, with the BBC running with “Vitamins 'undo exercise efforts'”, The Daily Telegraph (UK) having the headline, “Vitamin supplements may block benefits of exercise”, and the New York Times running with "Vitamins Found to Curb Exercise Benefits”.

For Dr Schauss’ full reaction, and reaction from others, please click here .

Source: Proceedings of the National Academy of Sciences
Published online ahead of print, doi: 10.1073/pnas.0903485106
“Antioxidants prevent health-promoting effects of physical exercise in humans”
Authors: M. Ristow, K. Zarse, A. Oberbach, N. Kloting, M. Birringer, M. Kiehntopf, M. Stumvoll, C.R. Kahn, M. Blüher

http://tinyurl.com/p7pey8

Just found yet another opinion:

Antioxidants needed by exercising populations: Nutritionist

By Stephen Daniells, 14-May-2009

Related topics: Research, Antioxidants, carotenoids, Vitamins & premixes, Energy & endurance
Conclusions that supplements of vitamins C and E may blunt the positive effects of exercise are a "gross over extrapolation of the experimental findings", says a nutrition expert.

German researchers have reported that antioxidant vitamins C and E may blunt the positive effects of exercise, with respect to insulin sensitivity. Findings were published in the Proceedings of the National Academy of Sciences.

Dr Rob Childs, nutritional biochemist for the Cervelo Pro Cycling Test Team, who are currently competing in the Giro D'Italia, told NutraIngredients.com that the study “forms part of popular trend claiming that antioxidants attenuate the adaptive responses to exercise”.

The German study used a combination of 1,000 mg per day of vitamin C and 400 IU per day of vitamin E, and investigated how insulin sensitivity was affected following 85 minutes of exercise five days per week for four weeks. Participants were both trained and untrained.

Responding to the findings, Dr Childs said: “Studies dating back to the 1980s have shown that antioxidants reduce muscle damage, while more recent investigations demonstrate that they can also improve both ventilatory and exercise performance. Such effects are of particular relevance to exercising populations.”

Commenting on the design of the study, Dr Childs said it was unclear if the subjects encountered the same absolute level of muscle fatigue during exercise in the supplement and control conditions and hence stimulus for antioxidant up-regulation. “Because of this, the reported ‘prevention of the ‘health promoting effects of antioxidants’ may be nothing more than an experimental artefact,” he said.

In addition, Dr Childs said that comments by the authors that antioxidants may block many of the beneficial effects of exercise were a “gross over extrapolation of the experimental findings on two levels”.

“Firstly, the study only investigated the effects of two free radical scavengers in a highly complex system involving hundreds of antioxidant compounds. This makes it inappropriate to extrapolate the study findings to other antioxidants.

“Secondly the potential advantages provided by antioxidant supplementation for attenuating muscle soreness and structural damage, while enhancing muscle recovery and performance were not assessed.

“The benefits provided by antioxidant supplementation on these parameters provide key drivers for their use by exercising populations,” said Dr Childs.

To read NutraIngredients.com’s coverage of the study, please click here .

To read other reaction to the study’s findings, please click here .

http://tinyurl.com/pbn9wc

[mellowsong]

This is all part of the disinformation campaighn to curtail the use of supplements. Unfortunately, the majority of John Q Public buys into this totally and are unable to see the flaws in these studies. I encounter this daily in the Yahoo groups I belong to...these are people fighting to take control of their health, yet they still read this stuff and freak out.