Autoimmune Thyroid Disease

An Unfortunate and Lengthy Adventure in Misdiagnosis

More problems with antioxidants and carbs

with 3 comments

It looks like all that evidence of increased lifespan due to calorie/carbohydrate restriction goes down the pan when you start taking antioxidants:

A new study in the October issue of Cell Metabolism, a publication of Cell Press, reveals that worms live to an older age when they are unable to process the simple sugar glucose. Glucose is a primary source of energy for the body and can be found in all major dietary carbohydrates as a component of starches and other forms of sugar, including sucrose (table sugar) and lactose.

“In the US and Europe, added sugar accounts for 15 to 20 percent of daily calories, and the breakdown of that sugar always generates glucose,” said Michael Ristow of the University of Jena in Germany and the German Institute of Human Nutrition Potsdam-Rehbrücke. If the findings in worms hold for humans, it “suggests that, in healthy people, glucose may have negative effects on life span.” The findings may also cast some doubt on the prevailing treatments for type 2 diabetes, all of which are aimed at lowering blood levels of glucose by increasing the amount of sugar taken up by body tissues, Ristow said.

What’s more, Ristow’s group further demonstrated in their report that antioxidants and vitamins given to the worms erased the life-extending benefits of sugar deprivation, raising questions about the widespread use of antioxidant supplements, according to the researchers.

In westernized countries, glucose represents a key dietary component since the most commonly ingested sugar, sucrose, contains equal amounts of glucose and fructose, the researchers noted. Nevertheless, it is a matter of debate whether glucose and other carbohydrates have a relevant effect on disease burden and mortality in humans, they said.

To begin to address the issue in the current study, the researchers exposed the nematode Caenorhabditis elegans to a chemical that blocked the worms’ ability to process glucose, producing a metabolic state the researchers said resembles that of dietary glucose restriction. That treatment extended the worms’ life span up to 20 percent, Ristow reported, noting that the observed gain extrapolated to humans would mean an additional 15 years of life.

Unable to depend on glucose for energy, the long-lived worms ramped up the activity of cellular powerhouses known as mitochondria to fuel their bodies, Ristow said. That mitochondrial activity led to the increased production of reactive oxygen species, sometimes referred to as free radicals. In turn, the worms’ defenses against “oxidative stress” increased, the researchers found.

Free radicals are usually considered harmful, Ristow said, and scientists have generally thought that exposure to them would shorten life span. The new findings suggest that, at least in some cases, the opposite may be true.

Indeed, even when the researchers returned the worms to their normal environment, allowing them to again use glucose for energy, the worms’ increased defenses and longevity persisted, Ristow said. In contrast, treatment with antioxidant vitamins prevented the oxidative stress and the defenses against it, eliminating the life-boosting effects. Ristow called the result “scary” because it means that, rather than being protective, antioxidant pills may actually leave the body more vulnerable by thwarting those natural defenses.

Ristow doesn’t recommend that people toss out their multivitamins just yet, however, cautioning that his findings were made in worms. He also noted that antioxidant-rich foods, including fruits and vegetables, contain thousands of substances—many of which have yet to be identified. While scientists don’t yet know what all those ingredients do, it’s clear that such natural foods support “healthy pathways,” Ristow said. Avoiding sweets may spell a longer life, study in worms suggests

After scientists discover – shock horror – that oxidation is as important as reduction, and the body self-regulates its defences against free radicals, note again the concilliatory “well antioxidants must be good in some way” paragraph concluding this article!

Of course, we are not worms. We have exactly the same mitochondria behaving in the same kind of way, but we’re couldn’t possibly be like worms…

Thanks to Chris again for this article too!

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Written by alienrobotgirl

4 October, 2007 at 2:46 pm

3 Responses

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  1. Very interesting, thank you

    Casdok

    5 October, 2007 at 9:29 am

  2. There’s a study going on here in the U.S., last I heard, to figure out once and for all why it is that cancer cells need so much glucose. The hypothesis is that cancer cells use glucose to protect from free radical damage, which–wait for it–may be worse for cancer cells than it is for healthy cells.The implications for antioxidant vitamin supplementation are interesting, to say the least, and this may explain why smokers who supplement vitamin A are more likely to get lung cancer. The cancer cells may in effect be saying, “Hey thanks buddy! Now we don’t have to work so hard to stay alive, so we can have LOTS OF BABIES!” *shudder*

    Dana

    26 November, 2007 at 11:14 am

  3. Great comment Dana. I suspect you are right!

    Alien Robot Girl

    26 November, 2007 at 5:08 pm


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