Cold Potatoes & Blood Glucose
Cooling a potato before it is eaten reduces its effect on blood sugar levels, according to Nutrition Research (2004;24:993–1004). This finding, which could also theoretically apply to other foods, could potentially help people with insulin disorders, such as diabetes or insulin resistance, to better control their conditions.
Eating food affects blood sugar (blood glucose) in ways that can affect health. Insulin, a hormone that lowers blood glucose levels by stimulating cells to take up glucose from the blood, is normally released when the glucose level in the blood rises after eating.
The glycemic index is a scale that measures foods’ effects by ranking them according to their ability to raise blood glucose levels. The rise in blood glucose that occurs after eating a food is compared with the rise that occurs after consuming either white bread or pure glucose to determine its glycemic index value. Chronic overeating of foods with a high glycemic index is believed to cause the cells to become resistant to insulin and increase the risk of type 2 diabetes (sometimes called adult-onset diabetes). Foods with a low glycemic index are recommended to people with insulin resistance and diabetes. A number of factors influence the glycemic index of a given food, including fiber, protein and fat content; how much it has been processed, and the way it is cooked. Another proposed factor is the temperature of a food at the time it is eaten.
The current study involved nine healthy men, aged 17 to 27, who were tested on three separate mornings after fasting the night before. The test measured blood glucose, insulin, cholesterol, and triglyceride levels before and for three hours after eating one of three test meals. The meals were hot boiled potatoes (83.6 °C, or 182.5 °F), boiled potatoes cooled to 26 degrees C (78.8 °F), or white bread, given to each participant in random order. Average blood glucose levels were significantly higher 30 minutes after the hot potato meal than after the cool potato meal, and remained so for three hours. Triglyceride levels dropped after eating the cool potatoes but increased after eating the hot potatoes; this difference was also significant 30 minutes after the meal and for the rest of the three hours. The glycemic index of hot potatoes relative to white bread, which was assigned a value of 100, was found to be significantly higher than for cool potatoes: 121 vs. 77.
As these results suggest that hot potatoes can raise blood glucose more than cool potatoes, it is possible that cooling cooked foods causes a shift in the structure of their starches that changes the rate at which glucose is absorbed. Whether further cooling would further diminish a food’s glycemic effects remains to be determined. The relationship between the temperature of other foods at the time they are eaten and their effect on blood glucose levels needs further exploration so that more accurate recommendations for diabetics and people with insulin resistance can be made.
Maureen Williams, ND, received her bachelor’s degree from the University of Pennsylvania and her Doctorate of Naturopathic Medicine from Bastyr University in Seattle, WA. She has a private practice in Quechee, VT, and does extensive work with traditional herbal medicine in Guatemala and Honduras. Dr. Williams is a regular contributor to Healthnotes Newswire.
Copyright © 2005 Healthnotes, Inc. All rights reserved. Republication or redistribution of the Healthnotes® content is expressly prohibited without the prior written consent of Healthnotes, Inc. Healthnotes Newswire is for educational or informational purposes only, and is not intended to diagnose or provide treatment for any condition. If you have any concerns about your own health, you should always consult with a healthcare professional. Healthnotes, Inc. shall not be liable for any errors or delays in the content, or for any actions taken in reliance thereon. HEALTHNOTES and the Healthnotes logo are registered trademarks of Healthnotes, Inc.