In the not-too-distant past it was assumed that a carbohydrate is a carbohydrate is the carbohydrate and it was thought that all types of carbohydrates has the same effect on blood glucose levels and health, so it didn’t matter what type is consumed. As in a case with many untested assumptions this one fell by the wayside. It is now known that some types of simple and complex carbohydrates in foods elevate blood glucose levels more than do others. This is called the glycemic response. Such differences are particularly important to people with disorders such as insulin resistance and type II diabetes.
What affects the glycemic response?
How quickly and how high blood glucose rises after carbohydrate is consumed is called the glycemic response. It is affected by both the amount and type of carbohydrate eaten and the amount of fat and protein in that food or meal. Because carbohydrate must be digested and absorbed to enter the blood, how quickly a food leaves the stomach and how fast it is digested and absorbed in the small intestine all affect how long it takes glucose to get into the blood.
A shortcoming of the glycemic index is that they are determined for individual foods, but we typically eat meals containing mixtures of foods. Knowing the glycemic index of a specific food does not tell us much about what the true glucose levels will be after eating this food as part of a mixed meal. For example, a bowl of white rice has a high glycemic index, but if the rice is part of a meal that contains chicken and broccoli, the rise in blood glucose is much less.
Refined sugars and starches generally cause a greater glycemic response then refined carbohydrates that contain fiber. The presence of fat and protein also slows stomach emptying, and therefore foods high in these macronutrients generally cause the smaller glycemic response than foods containing sugar or starch alone. For example ice cream is high in sugar but also contains fat and sugar, but it also contains fat and some protein, so causes a smaller rise in blood sugar or lower glycemic response than sorbet, which contains sugar but no fat or protein.
Source: Judith E. Brown, Nutrition Now, 7th Edition
Smolin and Grosvenor, Nutrition: Science and Applications, 3rd Edition
The effects of sugar in the body is currently being investigated particularly as to its effects on the brain. Therefore, it becomes important to understand how we handle sugar and what factors determine its effects on the glycemic response in order to more fully understand how it affects our health. The following article presents an interesting relationship of sugar on the brain and begins to elucidate influence in terms of a possible addiction process. This benefits not us, but more the food industry that often uses this alleged addiction to sell more sugary products.
From Marion Nestle, a Paulette Goddard Professor of Nutrition, Food Studies, and Public Health, Emerita, at New York University and author of books about Food Politics, most recently Unsavory Truth.
“It’s too bad for us that the principal sources of salt, sugar, and fat in the American diets are salty snack foods, sugary soft drinks, and fatty fried foods, respectively, all of them ultraprocessed junk foods deliberately formulated to make it hard for us to stop eating them.”
Source: Marion Nestle in Conversation with Kerry Trueman. Let’s Ask Marion: What You Need to Know about the Politics of Food, Nutrition, and Health. University of California Press, Oakland, California, 2020.