Could anybody tell me the in vitro method of determination for Glycemic Index of food material?
since GI is a measure of physiological glycemic response elicited by carbohydrate foods, standardized methods only recommend in vivo testing( > 10 healthy subjects). Any particular reason youbare looking for an in vitro method?
Dear Sajad,
The glycemic index ranks foods on a scale of 0 to 100 based on how quickly they raise blood sugar levels. Foods that raise blood sugar quickly have a higher number, whereas foods that take longer to affect blood sugar levels have a lower number.
To measure the glycemic index of a food, a specific weight of the digestible carbohydrates in the food (usually 50 grams, which is about 4 tablespoons of sugar) is fed to at least ten different people who volunteer for the study. Their blood sugar levels are measured every 15 to 30 minutes over a two-hour period to develop a blood sugar response curve. The blood sugar response of each food is compared to that of a test food, typically table sugar (glucose), which is assigned the number 100. The responses for each test subject are averaged, resulting in the glycemic index number for that food. Every individual person may have a slightly different glycemic (blood sugar) response to foods, which is why the tests use a number of volunteers and average their results together.
Regards,
Paul
Miss Sangeetha Shyam and Aman paul
I have to determine the glycemic index of food material without using the blood of a person, I want to say by using enzymes and chemicals. Is their any procedure, please tell me in full details. That will be your most kindness
Dear Sajad,
The in vitro measurement of glycemic index can be done through many techniques. One of the most popular one is the enzymatic hydrolysis followed my ionic chromatographic assay
Follow the link, for details:
http://www.agrobio-rennes.com/us/glycemic-index-gi-vitro-measurement
Regards,
Paul
The best recognized method for estimating glycemic index using an in vitro method is the Englyst Method
Klaus N. Englyst and Hans N. Englyst (2005). Carbohydrate bioavailability. British Journal of Nutrition, 94, pp 111
doi:10.1079/BJN20051457
But this is just an estimate. It needs to be confirmed using the standardized in vivo method.
Wolever et al., (2008) Measuring the glycemic index of foods: interlaboratory study. Am J Clin Nutr 87(suppl):247S–57S.
Dear Sajad Sir,
Kindly find the attachment attached along with this mail.
Irshaan
In my lab, we use in vitro methods for product development. We can use it to compare the effects of food processing parameters, for instance, how much water was added, how long foods were cooked, starch to fibre ratios. That way we can optimize processes before going to in vivo tests. We also use in vitro methods to investigate mechanisms. We have shown that the viscosity of soluble fibres slows starch digestion rates and glucose absorption rates.
Hi Sajad,
I think the best way to determine GI of foods is that based on in vivo method by using the standard method (Wolever et al, 2008). However, there is a high correlation between in vivo GI and in vitro CHO hydrolysis, the so called rapidly available glucose value (RAG value) by using Englyst method (Englyst KN, Hudson GJ and Englyst HN (2000). Starch analysis in food. In: Encyclopaedia of Analytical Chemistry. Chichester, United Kingdom, Wiley & Sons, 4246-4262)
It is very tricky and most of the methods suggested by fellow researchers may not work practically. It is true that in vivo method is standard and accurate. However, if one want to conduct the assay in vitro for various reasons, a standard protocol is in the published patent and it is available as a ready to use kit.
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