Glycemic load
Overview
The Glycemic Load (GL) is a ranking system for carbohydrate content in food portions based on their glycemic index (GI) and the portion size. It is a measure that considers the amount of carbohydrate in a portion of food together with how quickly it raises blood glucose levels. It was introduced by scientists from the Harvard School of Public Health in 1997 to provide a more comprehensive dietary tool, which not only considers the quality of carbohydrates, but also the quantity consumed.
Concept
The concept of glycemic load is based on the fact that different carbohydrates have different effects on blood sugar levels. The glycemic index measures how quickly a particular food raises blood sugar levels, but it does not take into account the amount of carbohydrate in a typical serving of that food. The glycemic load, on the other hand, considers both the quality and quantity of carbohydrate in food. It is calculated by multiplying the glycemic index of a food by the amount of carbohydrate in a serving, and then dividing by 100.
Calculation
The glycemic load of a food is calculated using the formula:
- GL = (GI x the amount of available carbohydrate) / 100
The 'available carbohydrate' is the total carbohydrate minus the dietary fiber. This is because dietary fiber is a type of carbohydrate that the body can't digest. As such, it does not raise blood glucose levels and is subtracted from the total carbohydrate content when calculating the glycemic load.
Interpretation
Glycemic load values can be interpreted as follows:
- Low (10 or less): Most fruits and vegetables, many whole grains, pasta, milk.
- Medium (11–19): White rice, white bread, breakfast cereals.
- High (20 or more): Refined sugar, sweets, sugary drinks.
A low GL diet can be beneficial for people with diabetes, as it can help to control blood sugar levels. It may also be beneficial for weight control.
Glycemic Load and Health
Research has shown that the glycemic load of a diet is associated with different health outcomes. High GL diets are associated with an increased risk of developing type 2 diabetes and cardiovascular disease. On the other hand, low GL diets are associated with a reduced risk of developing these diseases. However, more research is needed to fully understand the relationship between GL and health outcomes.