Nutrition

Glycaemic Index in food choices

GI definition according to betterhealth.vic.gov.au:

Carbohydrate-containing foods can be rated on a scale called the glycaemic index (GI). This scale ranks carbohydrate-containing foods based on their effect on blood sugar levels over a period of time – usually two hours.

Carbohydrate-containing foods are compared with glucose or white bread as a reference food, which is given a GI score of 100. The GI compares foods that have the same amount of carbohydrate, gram for gram. Carbohydrates that break down quickly during digestion have a higher glycaemic index (GI more than 70). These high GI carbohydrates, such as a baked potato, release their glucose into the blood quickly.

Carbohydrates that break down slowly, such as oats, release glucose gradually into the bloodstream. They have low glycaemic indexes (GI less than 55). The blood glucose response is slower and flatter. Low GI foods prolong digestion due to their slow break down and may help with satiety (feeling full).

There has been a lot of talk about GI and it’s effect on body, how we should be consuming low and medium GI food to keep us full longer and avoid the huge spike in insulin that comes with high GI food consumption. A lot of health and wellness websites recommend having mostly low GI food. To give you an idea, here is how foods are distributed according to the scale:

  • low GI (less than 55) – soy products, beans, fruit, milk, pasta, grainy bread, porridge and lentils.
  • medium GI (55 to 70) – orange juice, honey, basmati rice and wholemeal bread.
  • high GI (greater than 70) – potatoes, white bread and short-grain rice.

 

The Studies:

According to one study by The American Journal of Clinical Nutrition the GI values are not a good approach to guiding food choices because there is substantial variability in individual responses to GI value determinations. They concluded that even in healthy individuals, glycemic status significantly contributes to the variability in GI value estimates.

http://m.ajcn.nutrition.org/content/early/2016/09/06/ajcn.116.137208.abstract

Another study conducted in Nutrition Journal at BioMed Central concluded that even though cross-sectional studies have showed that higher GI means higher odds of metabolic syndrome, further controlled studies on low-GI diet and metabolic disease are needed. They compared median GI values of 84 and 72.

https://nutritionj.biomedcentral.com/articles/10.1186/1475-2891-8-5

Conclusion

Instead of blindly following the GI, we should concentrate on what is really important in nutrition. It needs to be satisfying, sustainable long term, having a lot of health benefits and working for us regardless of whether it is high, medium or low GI. It would be wrong to conclude that GI shows nothing or alternatively is extremely important. Make sure you have an open mind when reading information online.

 

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