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    Table 1 - Results
    Test Meal Glycemic Index
    1. Microwaved russet potatoes 76 8.7
    2. Instant mashed potatoes 87.7 8
    3. Oven-roasted white potatoes 73 8.2
    4. Microwaved white potatoes 72 4.5
    5. Boiled red potatoes 89 7.2
    6. Boiled red potatoes, refrigerated, and consumed cold 56 5.2
    7. French fries 63 5.5

    It is clear that both the method of cooking and variety of potato can affect Glycemic index. What was most interesting was when a red potato was boiled, refrigerated, and consumed cold the next day, the Glycemic index plummeted 37% from the upper end of a high Glycemic index food (89) to one point away from a classification of a low Glycemic index food (56)(see Table 2).

    Table 2
    Glycemic Index Glucose Scale
    High 70-100
    Medium 55-69
    Low 54 or less
    When potatoes are cooked, the starch granules absorb water. This is called gelatinization and tends to change the structure of the starch, making it more susceptible to the digestive enzymes. When the cooked potato starch is cooled, the molecules bond in an irregular fashion, making it more difficult to be hydrolyzed by enzymes. The authors mention that repeating the cooking-cooling cycle will continue to result in a more resistant starch. The more resistant a starch is, the longer it will take the body to break it down, digest, and absorb it.

    Please note this was only one small study. But the next time you read a GI chart the published values are far from absolute. In this case of red potatoes, eating them cold the next day makes a huge difference.
    Get on my Level

  • #2
    What about eating with fat like butter or sour cream, the only way I'll eat 'em.
    Wheat is the new tobacco. Spread the word.


    • #3
      I like to steam my potatoes (dont know where that fits into the GI index)
      Also important to note is that the GI of the meal is slowed considerably when we have enough fat and protein with that GI food.


      • #4
        Hey that's really interesting... and makes me hungry for homemade potato salad with red potatoes
        Jen, former Midwesterner, living in the middle of nowhere.


        • #5
          Thanks for posting this, that's very interesting! I'd never have imagined just the temperature (and/or the time they sit in the refrigerator) could make such a big difference for any food. I don't usually pay much attention to GI anyway, and now I think I'll continue that, haha.
          "mayness, you need to have a siggy line that says "Paleo Information Desk" or something!" -FMN <3

          I'm blogging again, at least a little bit.


          • #6
            The glycemic index is not reliable. It doesn't take portion size into consideration. Hence the reason carrots got such a bad rap with the low carb world.

            The glycemic load at least takes portion size into consideration.

            I don't worry about either. Eating protein and or fat with a meal slows digestion. Vinegar at a meal helps too. It can reduce blood sugar.

            The cooled potates are suppose to be better than hot due to resistant starch. Since I haven't done any scientific tests in my lab I can't say whether it is true or not. I don't have issue with either hot or cold potatoes though.