Postdelivery migraine.

Postpartum Migraine.

Friday, May 8th, 2009

What effect does fibre have on the G.I. value?

Dietary fibre is not one chemical constituent like fat and protein. It is composed of many different sorts of molecules. Fibre can be divided into soluble and insoluble types.

Soluble fibre tends to be viscous (thick and jelly-like) and will slow down digestion for this reason. Foods with more soluble fibre, like oats and legumes, therefore have low G.I. factors.

Insoluble fibre is not viscous and doesn’t slow digestion. Wholemeal bread and white bread have similar G.I. factors. Brown pasta and brown rice have similar values to their white counterparts. Sometimes insoluble fibre acts as a physical barrier which prevents the enzymes from attacking the starch. Whole (intact) grains of wheat, rye and barley have lower G.I. factors than cracked grains.

Bread has a G.I. of around 70 and lentils of around 29. Can I eat twice as much of the low G.I. food as the high G.I. food?

Yes, your blood sugar levels should be approximately the same after two serves of lentils or pasta compared with one serve of bread or potatoes. But, you will have eaten twice as many kilojoules (Calories). In practice, you will find that it is very difficult to eat a double serve of foods like lentils and pasta because they are very satiating and fill you up. If you can eat twice as much, it may be a good thing, because you are unlikely to have room for high-fat and less nutritious foods!