A matter of interpretation.

Discussion in 'Food and nutrition' started by Quentin Grady, Nov 3, 2003.

  1. G'day G'day Folks,

    I came across this intriguing research item while looking for something else.

    The interpretation of the decrease in red cell superoxide dismutase and plasma glutathione
    peroxidase as a decreased NEED for oxidative defenses rather than a decrease in oxidative defenses
    had me puzzled.

    Best wishes,

    "Red cell superoxide dismutase decreased by 69% (p<0.01) and plasma glutathione peroxidase dropped
    35% (p<0.01). Colonic function was improved on WUF. These changes indicate that the WUF diet
    decreased the need for oxidative defense mechanisms while inducing salutary effects on lipoproteins
    and colonic function."

    The Benefits of Phytochemicals and Fiber from Plant Foods on Lipid Metabolism, Antioxidant Defenses,
    and Colon Function -- Bonnie Bruce

    http://www.llu.edu/llu/nutrition/program/research2.htm

    Certain whole and unrefined foods such as sun-dried raisins, nuts, sesame seeds, whole grains, and
    green and orange vegetables and fruits contain high levels of antioxidant phenolics, fiber, and
    other phytochemicals recognized as being protective against chronic diseases. High rates of some
    cancers, heart disease, and poor colon function in industrialized countries are related to typical
    western diets high in animal foods, refined grain products and sugars. To study the effects of a
    typical western diet and one based on whole and unrefined foods (WUF) on lipoproteins, antioxidant
    defenses, and intestinal function, 12 hyperlipidemic women for four weeks consumed a diet low in
    fruits, vegetables and whole grains and then for four weeks consumed a diet rich in foods such as
    orange and green fruits and vegetables, whole grains, sun-dried raisins, nuts, sesame seeds, and
    olive oil. Calorie and fat intake were similar for both diets with saturated fat dropping by about
    one-third and fiber increasing by 159% on WUF. Tocopherols, other phenolics and carotenoids
    increased by about 500% and vitamin C by about 130%. WUF induced a drop of 16% (p<0.001) in low
    density lipoprotein and 19% in triglycerides, with no change in high density lipoproteins. Red cell
    superoxide dismutase decreased by 69% (p<0.01) and plasma glutathione peroxidase dropped 35%
    (p<0.01). Colonic function was improved on WUF. These changes indicate that the WUF diet decreased
    the need for oxidative defense mechanisms while inducing salutary effects on lipoproteins and
    colonic function.

    Thank you,

    --
    Quentin Grady ^ ^ / New Zealand, >#,#< [ / \ /\ "... and the blind dog was leading."

    http://homepages.paradise.net.nz/quentin
     
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  2. Mike V

    Mike V Guest

    Hi Quentin: Apparently these enzymes are assessed as markers for (responsive to) oxidative stress,
    rather than regarded as an antioxidant reserve?

    Glutathione Peroxidase (GSH-Px) Glutathione peroxidase is a selenium-dependant enzyme found
    primarily in the cytoplasm (70%) but also in the mitochondria (30%). Requiring four selenium atoms
    per active molecule, GSH-Px scavenges lipid peroxides throughout the membrane surfaces and
    quenches H2O2, converting it to water. Accumulations of oxidized lipids in mitochondrial and cell
    membranes have deleterious effects on function. Adequate levels of GSH-Px prevent this
    accumulation. The enzyme also participates in regeneration of the reduced (active) form of vitamin
    C . Studies indicate that low levels of GSH-Px activity are related to disease states.13-14 High
    levels of this enzyme have also been associated with certain conditions such as Alzheimer's
    dementia and Beta-Thalassemia minor.15-16 This perhaps reflects a response to increased amount of
    oxidative stress.

    By measuring reduced glutathione, glutathione peroxidase, and the lipid peroxides, the clinician can
    evaluate the relationship involved in maintenance of oxidative stress protection. Perhaps most
    importantly, evidence exists that supplementation with selenium is able to increase the levels of
    glutathione peroxidase in patients.17

    Superoxide Dismutase (SOD) This important enzyme is found in both the cell cytosol and the
    mitochondria. The cytosol form is dependant upon zinc and copper co-factors while the mitochondrial
    form requires manganese. As the name denotes, the superoxide radical is the substrate upon which
    the enzyme works, converting it to the less reactive H2O2 four times faster than if the enzyme were
    not present.

    As normal mitochondrial processes result in production of the superoxide radical, sufficient
    activity of Mn/SOD and GSH-Px protect this organelle from these damaging functional by-products.
    During periods of excessive muscular activity, this may be of particular importance. Investigations
    of SOD in clinical medicine include the observation that SOD is a sensitive marker for exposure to
    agricultural pesticides.18 SOD seems to be found at high levels in conditions such as systemic
    sclerosis, myositis, and malignant melanoma.19-21 SOD is decreased in patients with juvenile
    rheumatoid arthritis, affirming correlations of SOD and inflammation.22 SOD levels are also found to
    be low in patients with both early hyperglycemia AND impaired glucose tolerance.23 SOD levels were
    found to be low in experimental zinc deficiency research. This provides physicians with clear
    therapeutic rationale for modifying zinc nutriture.24

    Lipid Peroxides and Hydroxyl Radical Markers Lipid peroxides result from hydroxyl radical-attack on
    polyunsaturated fatty acids (PUFAs). Elevated levels of lipid peroxides are thus strongly suggestive
    of hydroxyl radical activity and reflect oxidative damage. The production of toxic radicals and
    metabolites is thought to be the main cause of much systemic damage. It has been suggested that
    hydroxyl radical attack upon membrane bound essential fatty acids (EFAs), leading to a loss of
    highly unsaturated EFAs, may have a direct relationship to EFA deficiencies, free radical damage and
    the aging process.25

    Catechol and 2,3-DHB are direct products of hydroxyl radical attack upon salicylic acid.26,27 The
    amount of 2,3-DHB appearing in the urine after an aspirin challenge appears to be a direct
    reflection of hydroxyl radical concentrations.27

    It is not surprising that 2,3-DHB has been reported to be a sensitive indicator of oxidative damage
    in diabetics.28 The research by Ghiselli suggests that hydroxyl radicals are involved in the
    pathogenesis of late complications in diabetes.

    Catechol is a minor metabolite of hydroxyl radical attack upon salicylic acid. Its generation
    involves the release of a molecule of carbon dioxide. Catechol is thought to correlate with 2,3-DHB
    as an additional indicator of oxidative stress.29,30

    From http://www.gsdl.com/assessments/oxidativestress/appguide/index.html

    Regards MikeV

    "Quentin Grady" <[email protected]> wrote in message
    news:[email protected]...
    > G'day G'day Folks,
    >
    > I came across this intriguing research item while looking for something else.
    >
    > The interpretation of the decrease in red cell superoxide dismutase and plasma glutathione
    > peroxidase as a decreased NEED for oxidative defenses rather than a decrease in oxidative defenses
    > had me puzzled.
    >
    > Best wishes,
    >
    > "Red cell superoxide dismutase decreased by 69% (p<0.01) and plasma glutathione peroxidase dropped
    > 35% (p<0.01). Colonic function was improved on WUF. These changes indicate that the WUF diet
    > decreased the need for oxidative defense mechanisms while inducing salutary effects on
    > lipoproteins and colonic function."
    >
    >
    > The Benefits of Phytochemicals and Fiber from Plant Foods on Lipid Metabolism, Antioxidant
    > Defenses, and Colon Function -- Bonnie Bruce
    >
    > http://www.llu.edu/llu/nutrition/program/research2.htm
    >
    > Certain whole and unrefined foods such as sun-dried raisins, nuts, sesame seeds, whole grains, and
    > green and orange vegetables and fruits contain high levels of antioxidant phenolics, fiber, and
    > other phytochemicals recognized as being protective against chronic diseases. High rates of some
    > cancers, heart disease, and poor colon function in industrialized countries are related to typical
    > western diets high in animal foods, refined grain products and sugars. To study the effects of a
    > typical western diet and one based on whole and unrefined foods (WUF) on lipoproteins, antioxidant
    > defenses, and intestinal function, 12 hyperlipidemic women for four weeks consumed a diet low in
    > fruits, vegetables and whole grains and then for four weeks consumed a diet rich in foods such as
    > orange and green fruits and vegetables, whole grains, sun-dried raisins, nuts, sesame seeds, and
    > olive oil. Calorie and fat intake were similar for both diets with saturated fat dropping by about
    > one-third and fiber increasing by 159% on WUF. Tocopherols, other phenolics and carotenoids
    > increased by about 500% and vitamin C by about 130%. WUF induced a drop of 16% (p<0.001) in low
    > density lipoprotein and 19% in triglycerides, with no change in high density lipoproteins. Red
    > cell superoxide dismutase decreased by 69% (p<0.01) and plasma glutathione peroxidase dropped 35%
    > (p<0.01). Colonic function was improved on WUF. These changes indicate that the WUF diet decreased
    > the need for oxidative defense mechanisms while inducing salutary effects on lipoproteins and
    > colonic function.
    >
    > Thank you,
    >
    > --
    > Quentin Grady ^ ^ / New Zealand, >#,#< [ / \ /\ "... and the blind dog was leading."
    >
    > http://homepages.paradise.net.nz/quentin
     
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