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    Rights: The University of Waikato
    Published 1 February 2007 Referencing Hub media

    How can you measure the effect different foods have on blood glucose levels in the person eating the food? And why does this matter?


    Alison Wallace, Plant & Food Research We take normal individuals, aged between 16 and 64 years. We bring them in fasting, and we feed them a food. We then follow the blood glucose response of over the next 2 to 3 hours.

    When they come into the clinic, we take two fasting samples 5 minutes apart. This is actually the most important reading of the morning. Everything is referenced back to this. If you don't get a good baseline, you can end up not getting such a good reading of the effect of the food.

    We feed them a food, and there’s a wide range of foods, anything from an apple, to a breakfast cereal, to even an ‘Up and Go’-type drink - a complete breakfast. We try to feed them this in amounts that they would actually eat. We then take blood samples over the next 2 to 3 hours. We take four blood samples in the first hour, and then another two, half an hour apart after that. So all up we take 8 samples in a morning, four of them in that first two hours.

    Sarah Eady, Plant & Food Research The blood glucose response for each individual is very different, so it depends entirely on that person.

    Alison Wallace, Plant & Food Research A low glycaemic load food will give a very balanced profile so it will give a more slow release over the 2 to 3 hours, and at the end of the three hours your blood glucose still may not be back to normal.

    Sarah Eady, Plant & Food Research A food that’s got a lot of available glucose - so if you took a glucose drink, say Lucozade, or white bread perhaps, because it’s got very, very available glucose - when you take it into your body it’s absorbed very quickly the glucose is in your bloodstream very quickly. Therefore you get that immediate peak that comes up and that’s telling us that that food would probably have a high glycaemic load because it’s got a lot of readily available glucose.

    Alison Wallace, Plant & Food Research You’ll actually see in the participants exactly what is going on in their blood. You will see that they’re dialed, they are up there, and they are really happy, and by the time that they have finished the testing they've actually slumped and they are ready for food.