Glycemic Index and Polyphenol Bioavailability of Potatoes (GI)

A Trial to Measure the Glycemic Index and Polyphenol Bioavailability of Four Different Varieties of Potato.

The purpose of this study is to determine the glycemic index of four varieties of potatoes and to determine the bioavailability of polyphenols contained in these potatoes.

Ten healthy persons will have a fasting blood sample drawn and asked to randomly consume a 50g glucose drink (2 occasions), or 50g carbohydrate equivalent of cooked purple, red, yellow and white potatoes. Further blood samples will be obtained at 15,30, 45, 60, 90, 120, 180, 240 mins. Bloods from the first 2 hours will be analyzed for glucose and insulin to determine the glycemic response. Hourly blood samples will be analyzed for polyphenol to determine the bioavailability of polyphenols from the different potato variety. Urine samples will be collected before ingestion of the food items and again at 4 hours, and will be used to determine polyphenol bioavailability.

the glycemic response top 50g available carbohydrates from 4 potato varieties will be compared to a 50g glucose standard

Inclusion Criteria: healthy, non-smoker on no medication normal glucose tolerance willing to have a catheter inserted in forearm Exclusion Criteria: abnormal glucose tolerance abnormal BMI on medication for a chronic disorder

Wolever TM, Brand-Miller JC, Abernethy J, Astrup A, Atkinson F, Axelsen M, Bjorck I, Brighenti F, Brown R, Brynes A, Casiraghi MC, Cazaubiel M, Dahlqvist L, Delport E, Denyer GS, Erba D, Frost G, Granfeldt Y, Hampton S, Hart VA, Hatonen KA, Henry CJ, Hertzler S, Hull S, Jerling J, Johnston KL, Lightowler H, Mann N, Morgan L, Panlasigui LN, Pelkman C, Perry T, Pfeiffer AF, Pieters M, Ramdath DD, Ramsingh RT, Robert SD, Robinson C, Sarkkinen E, Scazzina F, Sison DC, Sloth B, Staniforth J, Tapola N, Valsta LM, Verkooijen I, Weickert MO, Weseler AR, Wilkie P, Zhang J. Measuring the glycemic index of foods: interlaboratory study. Am J Clin Nutr. 2008 Jan;87(1):247S-257S. doi: 10.1093/ajcn/87.1.247S.

Ramdath DD, Isaacs RL, Teelucksingh S, Wolever TM. Glycaemic index of selected staples commonly eaten in the Caribbean and the effects of boiling v. crushing. Br J Nutr. 2004 Jun;91(6):971-7. doi: 10.1079/bjn20041125.

Wolever TM, Vorster HH, Bjorck I, Brand-Miller J, Brighenti F, Mann JI, Ramdath DD, Granfeldt Y, Holt S, Perry TL, Venter C, Xiaomei Wu. Determination of the glycaemic index of foods: interlaboratory study. Eur J Clin Nutr. 2003 Mar;57(3):475-82. doi: 10.1038/sj.ejcn.1601551.

Wolever TM, Isaacs RL, Ramdath DD. Lower diet glycaemic index in African than South Asian men in Trinidad and Tobago. Int J Food Sci Nutr. 2002 Jul;53(4):297-303. doi: 10.1080/09637480220138142.