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Thread: Are sugar and starch metabolically identical, thus health wise identical?

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  1. #1
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    Are sugar and starch metabolically identical, thus health wise identical?

    I was reading an article in the paper drawing attention to a UK health body's criticism of super market food which the supermarkets claimed was healthy, despite having 'high' levels of sugar. The article mentioned noodles which had ~38g of sugar per ~380g of noodles, which is only 10g of sugar/100g. This didn't seem to be a strong factor to criticise the supermarket food on, as as tangerines (mandarins) have 11g of sugar/100g. Other fruits have even higher proportions of sugar. Clearly I'm not suggesting that fruits are unhealthy because of sugar, or that super market noodles are healthy, but if you are going to criticise a food, picking out one factor in isolation seems pretty stupid to me.

    Additionally carb rich sources like rice, pasta and potatoes have high levels of starches (typically around ~20g/100g). Bread can be up to 50g of carbs/100g.

    As far as I'm aware starch and sugar are processed by the body in the same way, they are broken down into glucose and fructose and then further processed. Thus, ignoring other factors (such as any vitamins, minerals, fibre etc), eating a slice of white bread is just as healthy as eating a bowl of sugar.

    Am I correct about the metabolism of sugar and starches? Or are starches broken down slower, or into different constituent parts?

  2. #2
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    Starch breaks down to only glucose. Sugar to glucose and fructose. Very different
    Four years Primal with influences from Jaminet & Shanahan and a focus on being anti-inflammatory. Using Primal to treat CVD and prevent stents from blocking free of drugs.

    Eat creatures nose-to-tail (animal, fowl, fish, crustacea, molluscs), a large variety of vegetables (raw, cooked and fermented, including safe starches), dairy (cheese & yoghurt), occasional fruit, cocoa, turmeric & red wine

  3. #3
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    The big problem is this:

    Glucose can be easily metabolized by every tissue in your body, and if there is an excess, you just store it as glycogen. It only becomes a major problem if your glycogen stores are full and you have to store it as fat. Of course, most people on a SAD have full glycogen stored most of the time.

    Fructose is a huge problem because your liver is the only organ that can metabolize it, and there is no way to easily store it. This means that it takes more than five times as much glucose as fructose to produce an equivalent metabolic load on the liver. In many ways fructose acts on the liver in the same manner as ethanol. This is is why alcoholic an non-alcoholic liver disease pathology looks so similar, and why fructose consumption is a major risk factor for NAFLD. See this review for more details.
    Last edited by The Scientist; 02-23-2013 at 02:02 PM.

  4. #4
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    Quote Originally Posted by The Scientist View Post
    Fructose is a huge problem because your liver is the only organ that can metabolize it, and there is no way to easily store it. This means that it takes more than five times as much fructose as glucose to produce an equivalent metabolic load on the liver.
    Seems like it would be the other way around?

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    The claim that fruit creates a toxic load on the liver completely negates the entire premise behind the paleo/primal/ancestral way of eating. It's pretty ironic that so many people on this forum are completely blind to that fact.

    Humans evolved eating fruit; geographically we originated near the equator where fruit would have been sweet and plentiful all//most of the year. If fruit was toxic to the liver, our species would have died off tens or hundreds of thousands of years ago.

    Bottom line: starches and sugars aren't digested and metabolized exactly the same, but if you choose good quality sources, they are excellent for providing energy and building muscles, so go ahead and eat both in whatever amount you thrive on.

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    Quote Originally Posted by BestBetter View Post
    The claim that fruit creates a toxic load on the liver completely negates the entire premise behind the paleo/primal/ancestral way of eating. It's pretty ironic that so many people on this forum are completely blind to that fact.

    Humans evolved eating fruit; geographically we originated near the equator where fruit would have been sweet and plentiful all//most of the year. If fruit was toxic to the liver, our species would have died off tens or hundreds of thousands of years ago.

    Bottom line: starches and sugars aren't digested and metabolized exactly the same, but if you choose good quality sources, they are excellent for providing energy and building muscles, so go ahead and eat both in whatever amount you thrive on.
    1. It doesn't negate anything. Your liver is perfectly capable of metabolizing small amounts of fructose. It is just that sodas and fruit juices and processed snack stuffs have incredibly large amounts of it.

    2. Humans did evolve eating fruit, but it was wild fruit. Compare an apple or banana in a supermarket today to their ancestral species, and you will see that we have selectively bred the sugar content up many times over what it originally was. One large grocery store apple probably contains more than 10 times that of a crabapple. I am not saying that you should not eat apples, just that they (and other fruit high in sugar) should be eaten in moderation. No pre-agriculture human could have ever consumed the amount of fructose that we can by eating a big bowl of fruit salad, let alone a pepsi. This is why our liver treats fructose as a (potential) toxin. We evolved a series of enzymes to metabolize it, but only in small amounts because that is what the environment at the time required.

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    Quote Originally Posted by Artbuc View Post
    Seems like it would be the other way around?
    True. Typo corrected.

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    In some ways the bowl of sugar is healthier as fructose does not spike insulin, the GI index is lower.
    Whoever wrote the article either didn't understand what they were writing fully or poorly explained the issues.

  9. #9
    Timthetaco's Avatar
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    Starch, sugar, glycemic index, digestion, health effects...

    Twenty page thread minimum.

  10. #10
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    Quote Originally Posted by Timthetaco View Post
    Starch, sugar, glycemic index, digestion, health effects...

    Twenty page thread minimum.
    exactly!

    p.s.> TheScientist sounds like he's gone to lustig land.

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