Potatoes and glycaemic index – what this really means….
Over the last few years potatoes have got a little bit of a bad reputation as being unhealthy. So you might be thinking how does the humble potato that has been loved and eaten by many generations of kiwis all of a sudden be “bad” for us?
The glycemic index (GI) is a number associated with a particular type of food that indicates the food’s effect on a person’s blood glucose level and potatoes have been reported to have a high GI. However the GI doesn’t take into account the density of the carbohydrate in the food or the amount eaten. This is where Glycemic impact comes in. A recent article in the New Zealand Herald explains how this works below:
“The advantage of this measure is that it behaves like a nutrient – it has gram units and can be expressed as g/100g of food or g/serving of food, just like other nutrients on a food label. Potatoes are in fact an excellent source of low-density energy. This means that the energy we get from potato comes from carbohydrate (17kJ/g) rather than fat (34kJ/g) and is diluted about eight times with water. They are also a good source of vitamin C, a source of potassium and niacin, and if you keep the skin on a source of dietary fibre. The glycaemic impact of potato is easy to manage in a healthy diet. When potato is cooked the starch gelatinises and becomes digestible. But when you cool cooked potato and let it stand for a while the starch chains partially join up, and this slows down the speed they are digested. So starch in cold cooked potato is digested at a lower rate than in the hot potato, and correspondingly has a lower glycaemic impact per weight. In addition, the acid in the vinaigrette you add to your potato salad (lemon juice, lime juice, or vinegar) will slow stomach emptying which means the starch does not reach digestion/absorption sites in the small intestine as quickly and the glycaemic impact is less acute.”
So remember its not the potato, its what you do with it!