Glycaemic Index
NUTRITIONAL EDUCATION
What is the glycaemic index?
The glycaemic index (GI) of a food, defined as the area under the curve (AUC) of blood glucose following the consumption of 50 or 75 grams of available carbohydrates from the food itself, compared with the area under the blood glucose curve resulting from 50 or 75 g of glucose = 100, has emerged in the most recent nutritional literature as an interesting indicator of the metabolic effects of individual dietary components.
Indeed, numerous recent data suggest that low-GI foods have a more favourable effect on health, and particularly on the risk of developing metabolic diseases (such as diabetes) or cardiovascular diseases (such as myocardial infarction), compared to foods with a higher GI.
In particular, a high GI (which implies, in fact, a more substantial increase in blood glucose after consuming the food in question) induces a marked insulin response, the preferential metabolic utilisation of sugars at the expense of fats, and often a rapid drop in blood glucose (following the insulin response), with the subsequent reappearance of hunger, which tends to perpetuate this vicious circle.
A diet with a high average GI therefore increases the probability of the onset of overweight or obesity, lipid metabolism alterations, glucose intolerance and, ultimately, cardiovascular diseases.
Certain markers of chronic inflammation, such as C-reactive protein (CRP), the plasma levels of which correlate positively with cardiovascular risk, are also increased in individuals who consume a high-glycaemic-load diet.
What is glycaemic load?
The increase in blood glucose is determined by both the quality, or GI, and the quantity of metabolised carbohydrates. The actual glycaemic response caused by a food can be established by calculating the glycaemic load (GL): the GI is multiplied by the quantity of carbohydrates expressed in grams and divided by 100.
The Glycaemic Load (GL) is higher for foods containing high percentages of carbohydrates, especially if consumed in large quantities.
For example:
Type 00 white bread - in one portion (100g) of type 00 white bread there are 66.9 g of carbohydrates and the GI is 79.
The glycaemic load is (66.9 x 79) : 100 = 52.85, therefore GL = 52.85
Glycaemic index of certain foods, relative to glucose:
Foods
Glycaemic index
White bread
70 - 75
Cornflakes
72 - 87
Pasta (spaghetti)
38
Pasta (macaroni)
49
Boiled rice
46 - 69
Polenta
68 - 77
Pizza
55 - 75
Boiled potatoes
80 - 100
Beans
30 - 45
Apples
38
Cherries
24
Tomatoes
9
Apple juice
40 - 44
Orange juice
46 - 54
Soft drink (non-diet)
50 - 65
Honey
45 - 87
Sucrose
60 - 67
Glucose
100
FREQUENTLY ASKED QUESTIONS
FAQ
Nutrition and health: why food quality matters
Data emerging from nutritional scientific research has clearly demonstrated in recent years that diet and its components are capable of influencing health status, modulating many aspects of our body’s functioning in a favourable or unfavourable way.
For this reason, it is important to know not only the composition of foods, so as to include them correctly in the diet based on age, lifestyle and health status, but also the effects that different nutrients produce in the body.
The attention of experts, initially focused mainly on the caloric content of foods, the presence of carbohydrates, fats and proteins, and the absence of toxic substances or bacterial contamination, has progressively shifted towards the “functional” effects of nutrients.
Simple and complex carbohydrates: a distinction that is no longer sufficient
Regarding carbohydrates, often also known as “sugars”, until a few years ago their nutritional role was evaluated primarily by distinguishing them into “simple” and “complex”.
Fructose and sucrose, i.e. common table sugar, are examples of simple sugars. Starch-rich foods, on the other hand, are considered complex sugars because they consist of many glucose molecules linked together in long chains.
In the past, there was a tendency to prefer foods containing complex carbohydrates, based on the idea that they caused a more moderate increase in blood glucose and were therefore less harmful to health.
The glycaemic response varies from food to food
In reality, blood glucose responds in a very variable way even to the intake of complex carbohydrates.
For example, bread causes a greater increase in blood glucose than pasta, while potatoes cause it to increase even more. Even among simple sugars, there are important differences: fructose, for example, does not induce a significant increase in blood glucose.
This means that the distinction between simple and complex sugars, on its own, is not sufficient to understand the real effect of a food on the body.
The benefits of a low glycaemic index and load diet
Some controlled studies have shown that low-glycaemic-load diets improve, at least in the short term, weight and fat mass loss compared to high-glycaemic-load diets.
The reduction of the overall glycaemic load also represents a useful support in appetite regulation, in maintaining weight loss and therefore in controlling overweight.
Important cardiovascular risk parameters, such as triglycerides and HDL cholesterol, as well as indicators of the body’s inflammatory state, are also favourably influenced by the consumption of foods with a low glycaemic index and load.
Conversely, a diet rich in high-glycaemic-index foods is associated with an increase in circulating triglycerides, a reduction in HDL cholesterol and a higher risk of developing type 2 diabetes, also due to excessive insulin secretion and the resulting functional fatigue of pancreatic cells.
CONSULT THE INDICES
Tables with the G.I. of the most common foods
Consult the glycaemic index tables to guide you in choosing the most common foods and to better understand their impact on daily balance. A simple and immediate tool to compare different food categories and deepen the relationship between nutrition, glycaemic load and well-being.
