Insulin Index

What is the insulin index?

The insulin index (II) is a parameter that expresses the effect of a given food on the blood levels of the hormone insulin (insulinemia) within two hours (120 '). It can be detected in all foods but, to be meaningful, the result must refer to a caloric intake of 250 kcal / 1000 kj (costate element of the evaluation scale).

Features

Insulin index VS glycemic index

The insulin index represents the evolution of the most known glycemic index (GI), which expresses the effect of various foods on blood glucose levels (glycemia). However, the two parameters are also very different from each other; let's see why.

1. The first substantial difference between insulin and glycemic index is the measurement or evaluation of the foods in question. While, as we have seen, the insulin index is measured by keeping the caloric intake of food constant (250 kcal or 1000 kj), the glycemic one requires keeping the available carbohydrate concentration constant (which corresponds to 50 g).
2. Secondly, while the values ​​of the glycemic index are classified in reference to the parameter of pure glucose (50 g), those of the insulin index are scaled with reference to white bread (250 kcal). Note : in the past, even a second version of the glycemic index was classified according to the equivalent portion (50 g) of white bread.
3. Moreover, not necessarily a low glycemic index food has an equally low insulin index. Although not enough space is given to this concept, in fact, proteins - in particular the amino acids of which they are composed - represent a discreet stimulus for insulin secretion. The stimulation of free fatty acids, glycerol and intermediate molecules of the oxidation pathways on insulin secretion is also reduced, but not negligible.

From the few experimental studies conducted so far, it has emerged that for most foods there is a high correlation between the insulin index and the glycemic index (if one is high, the other is also high, and vice versa). Protein-rich foods (meat, fish and low-fat cheeses) and pastry products (rich in fats and refined carbohydrates), which induce an insulin response higher than expected, escape this rule.

Insulin index VS glycemic load

To complicate the situation there is also the glycemic load (GL). This third parameter, which can also be applied to a single portion of food, refers to the glycemic effect of a predominantly carbohydrate meal based on its glycemic index and available carbohydrate content (CHO). The glycemic load is calculated as follows:

GL = (GI x CHO expressed in g) / 100

It can be defined with certainty that, as the glycemic load increases, the glycaemia increases and consequently the insulin index; in the opinion of many, the glycemic load would be more related (compared to the glycemic index) to the insulin index.

High and low insulin index foods

A food, therefore, is defined as having a high insulin index when the concentration of insulin in the blood increases considerably. Conversely, foods with a low insulin index do not significantly affect the secretion of this hormone.

Insulin, glycemic index and satiating capacity of foods

The following table shows the satiety scores referred to the insulin and glycemic increase of various people subjected to an experimental analysis.

In particular, blood glucose and insulin scores were determined after feeding the participants (blindfolded, to avoid the influence of autosuggestion) with food portions having 239 kcal (1000 kj), recording the respective curves (glucose and insulin in the blood) for 120 minutes (2 hours) in relation to the values ​​of white bread.

The satiety index was established based on the amount of food consumed (buffet) by the subjects analyzed AFTER having consumed the food indicated in the table; the value was again compared to that of white bread, to which was attributed the number 100. The score INCREASED as LOWER was the quantity of food consumed at the buffet. In other words, foods that exceed 100 are more satiating than white bread and foods less than 100 less satiating than white bread.

Insulin Index Table

• The order of the list in the table is increasing with respect to the score of the insulin index (4th column from the left).
• The colored lines, written in bold type, show the average values ​​of the categories marked in legend.
• The "±" symbol indicates the uncertainty of the data; for example, 60 ± 12 means that there is a 95% probability that the score is between 60-12 (48) and 60 + 12 (72).

1. Rye bread containing 47% raw rye
2. Bread made from wheat flour
3. The authors of the satiety study stated that the amount of jellies administered tended to make the participants nauseated, which could have resulted in an incorrect satiety score.

Applications

Usefulness of the insulin index

Based on this initial evidence, the insulin index would appear to be a better parameter than the glycemic index in the dietary treatment of type II diabetes and hypertriglyceridemia. In theory, an increased secretion of insulin without a rise in glycemic levels can be positive or negative depending on how it is interpreted.

A food with a low glycemic index and a medium insulin index such as meat, in fact, contributes to decreasing blood glucose levels; this could therefore help in the treatment of type II diabetes. On the other hand, when the disease is not yet over, the increased demand for insulin could contribute to the progressive functional depletion of pancreatic beta cells.