The Glycemic Index of Potatoes
While a whole potato would seem on the surface to be a reasonably healthy choice compared with processed foods, spuds are a dud when it comes to their effect on your blood glucose level. Potatoes fall into the moderately high to high ranges on the glycemic index scale, which measures the effects of foods on blood glucose. Potatoes actually rank closer to table sugar, which consists of glucose and fructose, than to other starchy foods that contain long and complex chains of glucose, according to the Linus Pauling Institute.
Measuring Glycemic Index
Determining the glycemic index of a food requires tests on human volunteers to see how the food affects their blood glucose levels. The Linus Pauling Institute’s website explains that volunteers receive 50 grams of a test food such as a potato, and a control food such as pure glucose that contains exactly the same amount of carbohydrate, on a later day. Volunteers’ blood is drawn before eating and for several hours after eating, and blood glucose is measured at regular intervals.
Glycemic Load Food List
The Linus Pauling Institute reports that a medium-sized baked Russet potato has a glycemic index of 76. This means that the change in blood glucose over time after eating a baked potato is 76 percent of the change in blood glucose that occurs after eating the same amount of carbohydrate as pure glucose. Foods with lower glycemic index values tend to produce lower blood insulin levels, in addition to lower blood sugar levels, according to Harvard Health Publications.
- While a whole potato would seem on the surface to be a reasonably healthy choice compared with processed foods, spuds are a dud when it comes to their effect on your blood glucose level.
- Potatoes actually rank closer to table sugar, which consists of glucose and fructose, than to other starchy foods that contain long and complex chains of glucose, according to the Linus Pauling Institute.
The glycemic index varies depending on the type of potato -- Harvard Health Publications reports in its listing of the glycemic index of more than 100 foods. Using glucose to represent 100 on the glycemic index scale, boiled white potatoes have a glycemic index of 82, instant mashed potatoes have a value of 85, and sweet potatoes a value of 70. Potato chips, often criticized for processing that adds fats and sodium, actually have a lower glycemic index than other forms of potatoes -- at a value of 51.
Japanese Sweet Potato Nutrition
Researchers at the University of Toronto looked at the glycemic index of potatoes as it is affected by cooking method. In a 2005 study reported in the "Journal of the American Dietetic Association," they found that boiled red potatoes consumed cold fell in the intermediate range at 56, while roasted California white potatoes at 72 and baked Russet potatoes at 77 fell in the moderately high range. The high range included instant mashed potatoes at 88 and boiled red potatoes at 89.
If you want to lower the glycemic index of the potatoes in your diet, precook the potatoes and consume them cold or reheated, recommends nutritionists at Oxford Brookes University in England who tested eight varieties of potatoes commonly eaten in the United Kingdom. They found that potatoes with a waxy texture had medium glycemic index values, while those with a floury consistency had higher glycemic index values.
- The glycemic index varies depending on the type of potato -- Harvard Health Publications reports in its listing of the glycemic index of more than 100 foods.
- Using glucose to represent 100 on the glycemic index scale, boiled white potatoes have a glycemic index of 82, instant mashed potatoes have a value of 85, and sweet potatoes a value of 70.
Glycemic Load Food List
Japanese Sweet Potato Nutrition
Nutritional Difference Between Red Potatoes & Brown Potatoes
How to Calibrate a Freestyle Glucometer
What Is Glycemic Index of Plantains?
About the Chemical Makeup of a Potato
Glycemic Index for Grains
Low-Glycemic Foods List
Vitamins & Minerals in Potatoes
List of Good Carbs for Diabetics
- Linus Pauling Institute: Glycemic Index and Glycemic Load
- Harvard Health Publications: Glycemic Index and Glycemic Load for 100+ Foods
- Journal of the American Dietetic Association: Glycemic Index of Potatoes Commonly Consumed in North America
- The British Journal of Nutrition: Glycaemic Index Values for Commercially Available Potatoes in Great Britain
- Ek KL, Wang S, Copeland L, Brand-Miller JC. Discovery of a low-glycaemic index potato and relationship with starch digestion in vitro. Br J Nutr. 2014;111(4):699-705. doi:10.1017/S0007114513003048
- Fernandes G, Velangi A, Wolever TM. Glycemic index of potatoes commonly consumed in North America. J Am Diet Assoc. 2005;105(4):557-62. doi:10.1016/j.jada.2005.01.003
- Vega-López S, Venn BJ, Slavin JL. Relevance of the glycemic index and glycemic load for body weight, diabetes, and cardiovascular disease. Nutrients. 2018;10(10). doi:10.3390/nu10101361
- Bhupathiraju SN, Tobias DK, Malik VS, et al. Glycemic index, glycemic load, and risk of type 2 diabetes: Results from 3 large US cohorts and an updated meta-analysis. Am J Clin Nutr. 2014;100(1):218-32. doi:10.3945/ajcn.113.079533
- Jacobs S, Harmon BE, Boushey CJ, et al. A priori-defined diet quality indexes and risk of type 2 diabetes: The Multiethnic Cohort. Diabetologia. 2015;58(1):98-112. doi:10.1007/s00125-014-3404-8
- University of Sydney, Australia. Glycemic Index Database. 2017.
- American Diabetes Association. Grains and Starchy Vegetables. 2017.
An award-winning writer and editor, Rogue Parrish has worked at the Washington Post, the Baltimore Sun and at newspapers from England to Alaska. This world adventurer and travel book author, who graduates summa cum laude in journalism from the University of Maryland, specializes in travel and food -- as well as sports and fitness. She's also a property manager and writes on DIY projects.