Different types of breads are made from different types of flours. It is the type of flour that determines the quantity and quality of the carbohydrates in the resulting bread. Both white and whole wheat breads offer nutrients, including essential vitamins and minerals, but wheat bread contains a different combination of carbohydrates than white bread, so it has a different effect on your health.
Composition of Flours
Flour is made from wheat kernels, or berries. These kernels consist of three parts: the bran, the embryo and the endosperm. The bran is the outer covering of the grain. The germ is the embryo contained inside the kernel. The endosperm is the largest part of the kernel.
Wheat bread is made from flour using all three parts of the wheat. It is known as "whole grain" flour. Whole grain flour contains the nutrients found in the bran, the embryo and the endosperm.
White bread, on the other hand, is the finely ground endosperm of the wheat kernel only. Nutrients provided by the bran and embryo are stripped away in the process of making white bread.
Carbohydrates are classified as either simple or complex. The classification is based on their chemical structure. Simple carbohydrates have a relatively simple chemical structure made up of one or two sugar subunits, whereas complex carbs can have chemical structures made up of thousands of subunits. Both white and whole-wheat bread contain the same amount of simple carbohydrates -- 1.4 grams per serving.
Complex carbohydrates are made of simple sugars linked together in long, complex chains. Complex carbohydrates are broken down much more slowly, in order to release the energy stored in them. Examples of foods containing complex carbohydrates are whole grains and vegetables.
Both simple and complex carbohydrates are converted to glucose in the body and are used as energy.
Whole grain breads contain more complex carbohydrates than breads made from white flour alone.
The glycemic index method of classifying carbohydrates according to their effect on blood -- glucose replaces the older method of classifying carbohydrates according to their chemical structure. According to Harvard Health Publications, "the lower a food's glycemic index or glycemic load, the less it affects blood sugar and insulin levels."
White Bread Versus Wheat Bread
According to the Glycemic Index and Glycemic Load list from Harvard Health Publications, a typical serving size of white flour white bread has a glycemic load of 10. In contrast, the same serving size of whole wheat bread has a glycemic load of 9. Pumpernickel bread, on the other hand, has a glycemic load of 6.