"There is nothing either good or bad but thinking makes it so." William Shakespeare
The fact that not all carbohydrates are equally healthy has become the starting point of many concepts and debates of what carbs are good for us and what should be condemned.
The old school says that foods with a high so-called glycemic index like bread and potatoes should be avoided. The new school suggests that the glycemic index is not very important to those who don't have problems with blood sugar control, and we can simply ignore it.
First of all, what are carbohydrates and what is a glycemic index?
Carbohydrates are macronutrients; organic molecules made up of carbon, hydrogen and oxygen. We have two types of carbs: whole carbs (they look like real foods) and refined carbs (these don’t look like real foods).
The glycemic index was first introduced in 1981 to show how foods containing carbohydrates increase blood sugar levels and subsequent need for insulin. In other words, it’s information about how foods affect blood sugar and insulin - the lower the food’s glycemic index, the lower the spike in blood sugar and insulin levels.
Although the glycemic index shows how quickly a carb raises blood sugar, it doesn’t show how much sugar is in a serving. So, another index, so-called a glycemic load, was invented to include portion sizes. Different foods have a different glycemic index, for example, grapes have twice the glycemic index of grapefruit.
It's important to understand this properly so watch a short video to learn more:
In 2014, a board of scientists from the Harvard School of Public Health suggested that the glycemic values should be included both in the new dietary guideline and on food labels so that the public understands the glycemic response to foods. The evidence from studies regarding the relevance of the glycemic index, however, is inconsistent, and many questions remain unanswered.
The American Dietary Guidelines recommends that we eat whole and natural carbohydrates. Although the guidelines state that there is no relationship between the foods glycemic index and body weight, a large clinical trial published in 2010 showed otherwise.
In a recently published study in JAMA, researchers were looking at how foods with low glycemic index may affect most common risk factors for cardiovascular disease and insulin sensitivity. Scientists concluded that foods with low glycemic index didn’t lower cholesterol levels and other risk factors compared to foods with the highest glycemic index. In fact, the low glycemic foods lowered an insulin sensitivity that is the pancreas’s capacity to produce insulin in response to high blood sugar levels.
Another observational study enrolled 163 people at high risk of heart disease and type 2 diabetes. Researchers were looking at whether diets similar in calories and carbohydrates but composed of either high or low glycemic foods may have different effects on cardiovascular health.
All participants were advised to follow four different diets for five weeks at a time. Each diet included fruit, vegetables, beans, fish, poultry, lean meat and grains. Two diets were slightly higher in carbs than an average diet, and two were slightly lower. The study has shown that the lower overall amount of carb intake was associated with lower blood pressure and decreased cholesterol levels.
However, when two diets had similar amounts of carbs and calories, the low glycemic index didn’t improve insulin sensitivity and didn't decrease blood pressure and cholesterol levels. Other trials carried out for even longer have shown similar results.
Take home message
If you don’t have problems with blood sugar control like diabetes, pre-diabetes or insulin resistance syndrome, ignore the glycemic index and choose any whole grains, and high-fiber foods you want, simply because of the nutrients they contain.
The division between good carbs and bad carbs is artificial. All whole natural carbohydrates like vegetables, fruit, grains, seeds, nuts and legumes are healthy. You don’t need to worry that one type of fruit or grain has a higher or lower glycemic index unless you eat refined foods.
Refined carbs like sugary drinks, ice cream, candies, white bread, chips, crisps, or pastries lose most of their nutritious value through processing and are considered “empty calories.”
Not what the doctor ordered!