Q & A Month: why does yoghurt have a low GI?
Posted by kathryn in Uncategorized
Paul has asked the question – why do yoghurts that contain sugar still have a low GI?
In the pre-GI days of nutrition, carbohydrate foods were separated into two categories: simple and complex. This distinction was solely based on the stucture of the carbohydrate itself. It was believed complex carbohydrates were harder to breakdown and therefore better for you – because they kept you fuller for longer.
What affects the GI of a food?
However, research into the GI has shown it’s more complicated. Carbohydrate breakdown is less about the structure of the carbohydrate itself than the physical state of the carbohydrate in a particular food.
This can be seen when you compare the GI response of jasmine vs basmati rice.
The GI of a food can be affected by a number of factors including:
- the size of the carbohydrate particles
- the type of fibre in a food
- whether the food also contains fat
- how starch is stored in the food
What about yoghurt
Yoghurt contains carbohydrate, so it does impact blood sugar levels. However, it also contains other nutrients and has properties which slow down this glycemic response:
- yoghurt is slightly acidic
- yoghurt contains protein
- most yoghurt contains some fat
All these factors impact yoghurt’s GI, because they alter the rate at which your stomach empties food into the small intestines.
The GI is affected by the rate of digestion
After chewing and swallowing food, it travels down your oesophagus and hits your stomach. Your stomach is primarily concerned with breaking down proteins. Very little happens to carbohydrates in the stomach.
Instead it’s in the small intestines that carbohydrate absorption occurs. So any food which is held up in your stomach and only released slowly into the small intestines, will have a slower glycemic response.
The acidity of yoghurt, combined with it’s protein and fat, ensures a slow release into your small intestines. So yoghurt’s carbohydrate is broken down slowly and it has a low GI.