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Glycemic index of potatoes commonly consumed in North America

https://doi.org/10.1016/j.jada.2005.01.003Get rights and content

Abstract

Objective

To determine the effect of variety and cooking method on glycemic response and glycemic index of common North American potatoes.

Design

Study 1: subjects consumed 200 g Russet or white potatoes that were either (a) precooked, refrigerated, and reheated (precooked) or (b) cooked and consumed immediately (day-cooked). Incremental area under the curve was determined. Study 2: subjects consumed 50 g carbohydrate portions of white bread or potatoes (six different varieties and two different cooking methods). Glycemic index values were calculated. In both studies meals were consumed after a 10- to 12-hour overnight fast and finger-prick capillary-blood glucose was measured before and at intervals for 2 hours after consumption.

Subjects

The study groups were as follows: Study 1 comprised four men and six women, aged 20 to 44 and Study 2 comprised 11 men and one woman, aged 18 to 50.

Statistical analyses

Repeated measures analysis of variance with Newman-Kuels to protect for multiple comparisons (criterion of significance two-tailed P<.05).

Results

Study 1: Precooked Russet potatoes elicited lower area under the curve than day-cooked (P<.05), while precooking had no effect on boiled white potatoes. Study 2: The glycemic index values of potatoes varied significantly, depending on the variety and cooking method used (P=.003) ranging from intermediate (boiled red potatoes consumed cold: 56) to moderately high (roasted California white potatoes: 72; baked US Russet potatoes: 77) to high (instant mashed potatoes: 88; boiled red potatoes: 89).

Conclusions

The glycemic index of potatoes is influenced by variety and method of cooking and US Russet potatoes have only a moderately high glycemic index. Individuals who wish to minimize dietary glycemic index can be advised to precook potatoes and consume them cold or reheated.

Section snippets

Subjects

Two separate studies were performed using two separate groups of subjects. Study 1 comprised four men and six women (five white, five East Asian) 20 to 44 years of age [mean±standard error of mean (SEM)=24±2] with body mass index (BMI; calculated as kg/m2) 19.8 to 31.7 (mean±SEM=23.3±1.2) studied on six separate occasions. Study 2 comprised 11 men and one woman (three white, two East Asian, and seven South Asian, none of whom participated in Study 1) aged 18 to 50 years (mean±SEM=26±4), with

Study 1

Blood glucose responses for precooked and day-cooked US Russet and California White potatoes are shown in Figure 1. None of the differences in blood glucose concentration at any point in time were statistically significant. The mean AUC elicited by day-cooked Russet Burbank potatoes did not differ significantly whether baked in a microwave or conventional oven (138±11 vs 145±16 mmol×min/L, respectively). Precooked, Russet potatoes tended to elicit lower glycemic responses than day-cooked, but

Discussion

It has been suggested that consumption of North American potatoes should be limited because they have a very high glycemic index (6, 7, 8). Results of this study do not support such a sweeping generalization. In fact, glycemic index values of different types of potatoes commonly consumed in North America varied across a considerable range from a low of 56 to a high of 89. Two of the potatoes tested here had intermediate glycemic index values, and several, most notably baked Russet potato, had

Conclusions

This study demonstrated that glycemic index values of potatoes vary depending on their variety and method of preparation. The glycemic index of baked Russet potatoes was not as high as was commonly believed. Precooking and reheating or consuming potatoes cold (eg, potato salad) may result in a reduced glycemic response. Thus, individuals wishing to minimize dietary glycemic index may be advised to precook potatoes and consume them cold or reheated, while those wanting to maximize glycemic index

G. Fernandes is a dental student at the University of Toronto, Toronto, Ontario, Canada.

References (25)

  • K.J. Joshipura et al.

    Fruit and vegetable intake in relation to risk of ischaemic stroke

    JAMA

    (1999)
  • K.J. Joshipura et al.

    The effect of fruit and vegetable intake on risk for coronary heart disease

    Ann Intern Med

    (2001)
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    G. Fernandes is a dental student at the University of Toronto, Toronto, Ontario, Canada.

    Amogh Velangi is a dental student at New York University, New York.

    Thomas Wolever is a professor, Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, and President of Glycaemic Index Testing, Inc, Toronto, Ontario, Canada.

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