Question: I am trying to follow a low glycemic index diet because I have slightly elevated blood glucose. However, I love potatoes. I understand they have a high GI ranking. Can I eat them?
Answer: The glycemic index (GI) ranks carbohydrate-rich foods based on how they raise blood glucose levels. This is important for people with diabetes or pre-diabetes. Lower rankings have less of an effect on blood glucose than higher numbers. Low foods are at 55 or less; medium foods are 56-69; and high foods are 70-100. Potatoes generally rank above 55. But there are differences based on the type of potato and how it is prepared. For example, mashed potatoes have a GI of about 83, but instant mashed with cheese and butter are about 66. The fat and protein content help reduce the index number. In another twist, if you boil potatoes, the GI is in the low to mid 60s. But if you refrigerate the potatoes and eat them the next day, say as potato salad, the ranking is in the low to mid 20s.
The question, of course, is how to incorporate potatoes into a healthy diet that will help keep your blood glucose in control. The first thing to consider is portion size. The above rankings are based on a serving size of about 2/3 cup. So, eating less will have less of an impact on blood glucose. Second, when eating a high GI food, combine it with low GI foods. The two scores will “average out.” Some good examples of low GI foods are green vegetables, chickpeas, and most fruits. Animal proteins, including meats, poultry, and fish, and fats are not ranked on the GI because they have no carbohydrates. As such, these are also good additions to help reduce the overall effect of the carbohydrates. The primary researchers on this subject are at The University of Sydney. Visit their website for a full list of foods that have been tested (http://www.glycemicindex.com/index.php) and for tips on how to use the index to keep your blood glucose under good control.