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Primal diet - Pros and Cons?

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  • Originally posted by Derpamix View Post
    Fructose is not a toxic. It is a metabolite your body will produce on its own.
    Derpamix, don't take this personally, but I still don't think you have a good grasp on how digestion works.

    Comment


    • Originally posted by paleo-bunny View Post
      Fructose is a toxin that causes about 100 times more oxidative damage than glucose. It can only be metabolised by the liver, kidney cells to a much lesser extent and cancer cells. Hence the analogy with alcohol.

      The human body has no means of producing fructose that I'm aware of. There would be no rationale in its doing so.
      There is nothing similar between the two metabolically, or biologically.

      Fructose is the preferred fuel of sperm cells. It does make a certain amount.

      Why do you believe it to be a toxin?
      Make America Great Again

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      • Originally posted by SarahW View Post
        Derpamix, don't take this personally, but I still don't think you have a good grasp on how digestion works.
        Hey, that's okay!

        Make America Great Again

        Comment


        • Originally posted by Derpamix View Post
          There is nothing similar between the two metabolically, or biologically.

          Fructose is the preferred fuel of sperm cells. It does make a certain amount.

          Why do you believe it to be a toxin?
          I know that fructose is treated as a toxin as I'm a biochemistry graduate.

          The metabolic similarity I have already pointed out to you. Both alcohol and fructose have to be detoxed by the liver.

          When you said 'biologically' did you mean 'molecularly'?

          Even if you are correct about sperm cells, they obviously don't have significant capacity to help out the liver in detoxing fructose thus they are equally irrelevant for males as they are for females in terms of this discussion.
          F 5 ft 3. HW: 196 lbs. Primal SW (May 2011): 182 lbs (42% BF)... W June '12: 160 lbs (29% BF) (UK size 12, US size 8). GW: ~24% BF - have ditched the scales til I fit into a pair of UK size 10 bootcut jeans. Currently aligning towards 'The Perfect Health Diet' having swapped some fat for potatoes.

          Comment


          • Originally posted by paleo-bunny View Post
            I know that fructose is treated as a toxin as I'm a biochemistry graduate.

            The metabolic similarity I have already pointed out to you. Both alcohol and fructose have to be detoxed by the liver.

            When you said 'biologically' did you mean 'molecularly'?

            Even if you are correct about sperm cells, they obviously don't have significant capacity to help out the liver in detoxing fructose thus they are equally irrelevant for males as they are for females in terms of this discussion.
            Being a biochemisty graduate isn't proof of anything, no offense. The only tests that have been done on this have shown unrealistically high doses of pure fructose. Effects taper off as dosages are lowered. It's literally impossible to consume toxic amounts of fructose. It's like with anything else.

            What's absent is the metabolic pathway.

            Considering that fructose has been shown to protect the liver:

            http://ajpgi.physiology.org/content/253/3/G390.short

            To say that it's treated like a toxic is a fallacy
            Make America Great Again

            Comment


            • Originally posted by Derpamix View Post
              Being a biochemisty graduate isn't proof of anything, no offense. The only tests that have been done on this have shown unrealistically high doses of pure fructose. Effects taper off as dosages are lowered. It's literally impossible to consume toxic amounts of fructose. It's like with anything else.

              What's absent is the metabolic pathway.

              Considering that fructose has been shown to protect the liver:

              Fructose prevents hypoxic cell death in liver

              To say that it's treated like a toxic is a fallacy
              It seems you don't understand what a toxin is. It's the liver's job to metabolise toxins. Hence, any metabolite processed almost exclusively by the liver is de facto a toxin. No offense, but if you had a biochemistry degree, that would be trivial to you.

              The gut protects the rest of the body from fructose by having a variable limited permeability to fructose. So often the gut takes the hit, rather than the liver.

              As I said before, fructose is 100 times as oxidising as glucose.

              Rat studies (as per your link) are irrelevant to humans.
              F 5 ft 3. HW: 196 lbs. Primal SW (May 2011): 182 lbs (42% BF)... W June '12: 160 lbs (29% BF) (UK size 12, US size 8). GW: ~24% BF - have ditched the scales til I fit into a pair of UK size 10 bootcut jeans. Currently aligning towards 'The Perfect Health Diet' having swapped some fat for potatoes.

              Comment


              • Originally posted by paleo-bunny View Post
                It seems you don't understand what a toxin is. It's the liver's job to metabolise toxins. Hence, any metabolite processed almost exclusively by the liver is de facto a toxin. No offense, but if you had a biochemistry degree, that would be trivial to you.

                The gut protects the rest of the body from fructose by having a variable limited permeability to fructose. So often the gut takes the hit, rather than the liver.

                As I said before, fructose is 100 times as oxidising as glucose.

                Rat studies (as per your link) are irrelevant to humans.
                Liver has the highest capacity, but other organs do metabolize it and skeletal muscles can metabolize fructose via the Glut5 expression.

                There is also this:
                Metabolic effects of fructose and the worldwide ... [Physiol Rev. 2010] - PubMed - NCBI

                They found that 50 percent ends up as glucose, 25 percent goes to lactate and greater than 15 percent goes to glycogen. The remainder is oxidized directly (to CO2 through the TCA cycle) and a small portion – as low as 2-3% – is converted to fat via de novo lipogenesis.
                There is no evidence to suggest that fructose is a toxin, nor does your analogy of toxins hold up.
                Last edited by Derpamix; 12-29-2012, 04:26 PM. Reason: typing errors
                Make America Great Again

                Comment


                • Originally posted by Derpamix View Post
                  Liver has the highest capacity, but other organs do metabolize it and skeletal muscles can metabolize fructose via the Glut5 expression.

                  There is also this:
                  Metabolic effects of fructose and the worldwide ... [Physiol Rev. 2010] - PubMed - NCBI



                  There is no evidence to suggest that fructose is a toxin, nor does your analogy of toxins hold up.
                  It's not an analogy - it's a definition.

                  It does hold up. If fructose was such a great thing then our livers would perform fructoneogenesis. They don't.

                  Glucose is a way superior, healthier energy source, thus most people report much better energy levels and health from consuming safe starch over sugar.
                  F 5 ft 3. HW: 196 lbs. Primal SW (May 2011): 182 lbs (42% BF)... W June '12: 160 lbs (29% BF) (UK size 12, US size 8). GW: ~24% BF - have ditched the scales til I fit into a pair of UK size 10 bootcut jeans. Currently aligning towards 'The Perfect Health Diet' having swapped some fat for potatoes.

                  Comment


                  • When fructose goes to the liver, is it definitely to be metabolised? If 50 percent of metabolised fructose ends up as glucose, is it possible that fructose goes to the liver because the liver stores glucose (in the form of glycogen)?

                    Those are genuine questions. I have no idea! But initially I was so wowed by Lustig's video. I've since watched it probably 8 times, and the more I watch it the less sure of it I am. I don't trust Lustig. Why is he so angry? By and large, where there's anger, there's an agenda. Plus I work in media, and I have an innate distrust of sensationalism. I saw him interviewed in "The Men who made us fat" and he seems like a bit of a media whore.

                    I know that sounds like a stupid reason to discount something that seems well presented, but I'm sure Ancel Key's research looked great at the time too.
                    Last edited by YogaBare; 12-29-2012, 04:56 PM.
                    "I think the basic anti-aging diet is also the best diet for prevention and treatment of diabetes, scleroderma, and the various "connective tissue diseases." This would emphasize high protein, low unsaturated fats, low iron, and high antioxidant consumption, with a moderate or low starch consumption.

                    In practice, this means that a major part of the diet should be milk, cheese, eggs, shellfish, fruits and coconut oil, with vitamin E and salt as the safest supplements."

                    - Ray Peat

                    Comment


                    • Anyway, that whole video is about fructose being a poison. Lustig himself says that "glucose is good carbohydrate. Glucose is the energy of life." Sugar is 50% fructose, 50% glucose. Shouldn't the video be called "Fructose - the bitter Truth"?
                      "I think the basic anti-aging diet is also the best diet for prevention and treatment of diabetes, scleroderma, and the various "connective tissue diseases." This would emphasize high protein, low unsaturated fats, low iron, and high antioxidant consumption, with a moderate or low starch consumption.

                      In practice, this means that a major part of the diet should be milk, cheese, eggs, shellfish, fruits and coconut oil, with vitamin E and salt as the safest supplements."

                      - Ray Peat

                      Comment


                      • Unlike glucose, fructose enters the glycolytic pathway in the liver after the rate-determining step, hence most of it is metabolised down to pyruvate very quickly which can either be used for energy production in mitochondria or converted to fat. Very little is converted to glucose normally.

                        This is why excessive fructose tends to cause build up of fatty acids in the liver, especially in metabolic syndrome. There is nowhere else for it to go, as unlike glucose it is not taken up by muscles for future energy storage in the form of glycogen, nor is it readily converted to glycogen in the liver.

                        I agree YogaBare - the video should be called 'Fructose - the bitter truth'.
                        F 5 ft 3. HW: 196 lbs. Primal SW (May 2011): 182 lbs (42% BF)... W June '12: 160 lbs (29% BF) (UK size 12, US size 8). GW: ~24% BF - have ditched the scales til I fit into a pair of UK size 10 bootcut jeans. Currently aligning towards 'The Perfect Health Diet' having swapped some fat for potatoes.

                        Comment


                        • Originally posted by Derpamix View Post

                          Considering that fructose has been shown to protect the liver:

                          Fructose prevents hypoxic cell death in liver

                          To say that it's treated like a toxic is a fallacy
                          I think this study Long-Term Fructose Consumption Accelerates Glycation and Several Age-Related Variables in Male Rats is far more explanatory about the overall function of fructose than a study seeing what fructose does in the liver in the absence of oxygen.

                          I make sure to avoid hypoxia at all costs, so by also avoiding fructose I will also live longer. Simple.

                          Comment


                          • Originally posted by paleo-bunny View Post
                            Unlike glucose, fructose enters the glycolytic pathway in the liver after the rate-determining step, hence most of it is metabolised down to pyruvate very quickly which can either be used for energy production in mitochondria or converted to fat. Very little is converted to glucose normally.

                            This is why excessive fructose tends to cause build up of fatty acids in the liver, especially in metabolic syndrome. There is nowhere else for it to go, as unlike glucose it is not taken up by muscles for future energy storage in the form of glycogen, nor is it readily converted to glycogen in the liver.

                            I agree YogaBare - the video should be called 'Fructose - the bitter truth'.
                            "It appears that fructose is a better substrate for glycogen synthesis than glucose and that glycogen replenishment takes precedence over triglyceride formation." -wikipedia.

                            PB, do you think that keeping liver glyogen filled is a good thing or do you think all fructose should be avoided?

                            Comment


                            • After a good workout you need muscle glycogen to be refilled, forget about liver stores. And even then, the need is not immediate to restore muscle glycogen unless you plan on going hard for round two right away. Heh.

                              Just make sure you've had a good meal before your next workout, whenever that is.
                              "The cling and a clang is the metal in my head when I walk. I hear a sort of, this tinging noise - cling clang. The cling clang. So many things happen while walking. The metal in my head clangs and clings as I walk - freaks my balance out. So the natural thought is just clogged up. Totally clogged up. So we need to unplug these dams, and make the the natural flow... It sort of freaks me out. We need to unplug the dams. You cannot stop the natural flow of thought with a cling and a clang..."

                              Comment


                              • Originally posted by Zach View Post
                                ...do you think that keeping liver glyogen filled is a good thing or do you think all fructose should be avoided?
                                I'm sure she will answer, but I have a question....why do you believe its an either or question? Are there no other sources for refilling liver glycogen besides fructose?

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