title: Glycemic index of potatoes commonly consumed in North America.
abstract: OBJECTIVE
  To determine the effect of variety and cooking method on glycemic response and glycemic index of common North American potatoes.
  
  
  METHODS
  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.
  
  
  METHODS
  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.
  
  
  METHODS
  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.
authors.affiliation: University of Toronto, Ontario M5S 3E2, Canada.
authors.forename: Glen
authors.initials: G
authors.lastname: Fernandes
authors.forename: Amogh
authors.initials: A
authors.lastname: Velangi
authors.forename: Thomas M S
authors.initials: TM
authors.lastname: Wolever
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D019540:Area Under Curve; D001786:Blood Glucose / Q000032:analysis* / Q000378:metabolism; D001939:Bread / Q000145:classification; D003296:Cooking / Q000379:methods*; D018592:Cross-Over Studies; D005260:Female; D005511:Food Handling / Q000379:methods; D038321:Glycemic Index; D006801:Humans; D008297:Male; D008875:Middle Aged; D009656:North America; D011198:Solanum tuberosum / Q000145:classification* / Q000378:metabolism*; D013997:Time Factors
chemical_list: D001786:Blood Glucose