Glycemic Index

This just in - a potential update on the glycemic index!  We already know that the glycemic index may help predict the blood sugar effects of a food, but when combining is involved things get a little muddied.  If you are not familiar with the glycemic index it is a ranking of how much standardized portions of foods raise your blood sugar.  The problem is though that most of use eat combinations of food rather than a single food on its own.

With that in mind, scientists from Tufts' studied the effects of blood sugar and insulin when adding different amounts of carbohydrate, protein, fat or fiber to a standardized portion of white bread.  They discovered that when they added 7 ounces of tuna (protein) that there was a positive effect - meaning that the glycemic response was 25% less! However, when they added rice cereal to the white bread there was a rise in blood sugar.

The researchers were not surprised that the addition of protein lowered blood sugar because protein slows stomach emptying. That means, that the carbohydrate from the bread would be delayed in entering the bloodstream.  Oddly, adding fat did not show the same results as adding protein.  One theory for that is that perhaps the butter (fat) that was used was not consumed in an amount large enough to slow absorption.

Takeaway:  More studies need to be done on how different combinations of food affect blood sugar and insulin.  For now, it is best to follow a healthy eating pattern with moderate portions.

Reference:  Health & Nutrition Letter, Tufts University, September 2017, VOL. 35, NO.7, New Insights: Glycemic Index (p.3).