Nancy's Nutrition Corner

"Let food be thy medicine and medicine be thy food," Hippocrates.

Pleasing Potatoes

Whenever I think about potatoes, my mind immediately goes to the Glycemic Index. Maybe that's because I’m a naturopath, but really – everyone should think about the GI when potatoes come to mind! Let me explain...

The Glycemic Index (GI) is a system of measuring the quality of carbohydrates based on their direct effect on blood glucose levels. In general, refined grain products and potatoes have a high GI, meaning these foods quickly raise blood sugar levels. Low GI foods include fruits and vegetables, beans, and whole grains; these foods do not create big spikes in blood sugar levels. The GI values of a food can be affected by factors such as the method of cooking and preparation.

Recently, studies on high GI foods and their affects on health have provided new insights into the relationship between dietary habits and disease. These studies reveal that diets with a high glycemic load play a direct role in the development of certain diseases. Chronic consumption of a diet with a high glycemic load is associated with an increased risk of obesity, type 2 diabetes, heart disease, and colon and breast cancers.

What does all this have to do with delicious potatoes? Well, historically, potatoes have been considered relatively high on the Glycemic Index. Newer studies, however, show that this is not as straightforward as we originally thought. It turns out that it actually depends on the variety of potato and the manner in which it is prepared and served. The serving temperature affects the GI because of the ways that digestive enzymes interact with cool vs. warm starch molecules. In other words--warm starch molecules are digested quickly and therefore raise blood sugar levels rapidly. Here are some examples: boiled red potatoes consumed cold: 56 (this number is considered to be a medium rating on the GI), roasted white potatoes: 72, potato chips: 75, microwaved white potato: 82, baked russet potatoes: 85, instant mashed potatoes: 88, boiled red potatoes consumed warm: 89 (this number ranks as a high rating on the GI).

All that being said, potatoes can be a good and tasty part of a healthy diet. Potatoes are a rich source of vitamin C, vitamin B6, copper, potassium, manganese, and fiber. They also contain a variety of phytonutrients which exhibit antioxidant activity. If you enjoy eating potatoes but are concerned about keeping your GI low, eat them at a meal where you are also consuming some protein or fat. These foods will help slow down the digestion rate, thus moderating your blood sugar level. Meat and potatoes it is!

Nancy Silva, ND is a licensed naturopath with a penchant for good food. Her monthly column discusses the nutritional aspects of some of the foods available through LocalHarvest. You can contact Nancy from her listing on our website.

Back to the September 2008 Newsletter