If you're like most people, you know diet is an important part of staying healthy and keeping your weight under control. Ingredients in foods can appear very similar, and yet be very different in how they affect your body. One example is whole grain wheat and bleached wheat flour. Despite the similar-sounding names, these affect your body in different ways.
Whole Grain
All grains, including wheat, have a few key parts. Two of the most important parts with regard to the grain's effect on the human body are the bran, or outer husk, and the inner starch. Whole grain, like whole wheat flour, is made by grinding the entire kernel of grain -- including the bran. Refined flours, including bleached wheat flour, are made by removing the outer bran and grinding only the inner starch. Bleached flour is then further refined by chemically whitening the resulting starch flour.
Starch Chemistry
Starch in grains, including starch from wheat, is made up of a chemical called amylose. Amylose consists of long chains of glucose molecules, where glucose is a kind of sugar, explain Drs. Reginald Garrett and Charles Grisham in their book "Biochemistry." Your intestine can't absorb amylose, but you can digest amylose into glucose, which you absorb into the bloodstream. From there, your body cells take up the glucose and use it as a source of nutrition.
Fiber Chemistry
Like starch, fiber is made up of long chains of glucose molecules. Unlike starch, however, your body can't digest fiber, meaning you can't take up the glucose and use it for energy. When you eat a combination of fiber and starch, you digest the starch and absorb its glucose, but you don't digest the fiber -- instead, it passes through your intestine and assists with intestinal function.
Eating Flour
When you eat whole grain wheat flour, the fiber interferes with the digestion of starch and absorption of glucose, slowing the rate at which glucose enters your bloodstream. This helps to keep your blood sugar more stable, and reduces the degree to which your cells store excess glucose as fat, note Drs. Mary Campbell and Shawn Farrell in their book "Biochemistry." When you eat refined flours, like bleached wheat flour, you absorb the glucose very quickly, and tend to store more of the sugar as fat.
Other Fiber Effects
Rate of digestion aside, another important difference between whole grain flour and bleached flour is the fiber in whole grain flour serves other significant purposes in the body. For instance, fiber helps keep your digestive system regular, and prevents constipation. Further, fiber absorbs cholesterol and certain toxins from the digestive tract, and helps to keep you from absorbing the chemicals. By choosing whole grain flour over bleached flour, you ensure you're keeping your blood sugar more stable, reducing fat storage and optimizing digestive function.
References
- "Biochemistry"; Reginald Garrett, Ph.D. and Charles Grisham, Ph.D.; 2007
- "Biochemistry"; Mary Campbell, Ph.D. and Shawn Farrell, Ph.D.; 2005
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