Diabetics, and anyone watching the glycemic load from their food knows that potatoes, with their large amount of starch, raise blood sugar levels. The otherwise high nutrient value of a potato, then, must be balanced against the body’s ability to supply the insulin necessary to stabilize the amount of glucose running around.
Look at this chart, from nutrition expert G. Douglas Andersen:
|Test Meal||Glycemic Index|
|1. Microwaved russet potatoes||76 ± 8.7|
|2. Instant mashed potatoes||87.7 ± 8|
|3. Oven-roasted white potatoes||73 ± 8.2|
|4. Microwaved white potatoes||72 ± 4.5|
|5. Boiled red potatoes||89 ± 7.2|
|6. Boiled red potatoes, refrigerated, and consumed cold||56 ± 5.2|
|7. French fries||63 ± 5.5|
The way it was cooked makes a huge difference. The starches in the potato break down and change when cooked and stored cold. The affect on glycemic load is even greater if you mix the potatoes with vinegar.
I’m not saying anything original here — diabetics and others have known this for a long time — but it’s interesting to me because it shows again how limiting it is to look simply at out-of-the-box nutrition labels if you want to know whether something is good for you.