How does dietary fiber affect on nutrients (carbohydrates, lipids, minerals and vitamins) absorption?

Contents

1. Interaction of dietary fibers with carbohydrates absorption
2. Interaction of dietary fibers with dietary lipids absorption
3. Interaction of dietary fibers with mineral absorption
4. Interaction of dietary fibers with Vitamins absorption
5. Other related topics

Interaction of dietary fibers with carbohydrates absorption

Most, though not all, the results of feeding or administering various preparations of dietary fibers, particularly in the soluble gel forms indicate that dietary fibers modulate the absorption of carbohydrates in the small intestine. Incorporating such preparation into carbohydrate-containing meal has been shown to reduce gastric emptying and post-prandial hyperglycemia and insulinemia in both normal and diabetic subjects.

There is some evidence to suggest that the activity of the pancreatic enzymes, amylase, lipase, trypsin and chymotrypsin can be altered in vitro by incubation with dietary fiber polymers. It is difficult to draw any firm conclusions from these studies.

The mode of action of insoluble dietary fibers is less well understood. It may interfere with enzymes access to carbohydrates substrates. High carbohydrate, high fiber diets have been shown to be effective in diabetes and to improve indices of diabetic control. Diets high in dietary fibers improve diabetic control independent of the amount of carbohydrates in the diet.

Interaction of dietary fibers with dietary lipids absorption

Both soluble and insoluble dietary fibers have been shown to alter fat absorption, with a decrease in apparent digestibility and increase in fecal fat. The increase in fecal fat is, however, nutritionally insignificant, with absorption remaining well over 95%.

There is some evidence that dietary fiber slower cholesterol absorption in the small intestine, demonstrated by both in vitro and in vivo experiments on the rat. It has been suggested that the action of dietary fiber in inhibiting cholesterol uptake in the small intestine is similar to that proposed for absorption of sugars. However, the interaction between soluble fiber and lipid micelles and reduced fluid movement in the presence of viscous fiber may also be important considerations. More studies are needed to elucidate the influence of dietary fibers on cholesterol absorption.

Interaction of dietary fibers with mineral absorption

In all discussion of the potential benefits of increasing the level of dietary fibers, at least one warning is always sounded: fiber interacts with dietary minerals, changing the micronutrients balance, and persons on marginal intakes may be at risk on increasing the dietary fiber intake. Dietary fiber can alter the absorption of calcium, zinc, iron, phosphorus and magnesium.

It is seen that not all fibers behave alike in affecting mineral bioavailability. Wheat bran is the most active. Fiber seems to have little or no nutritional consequences on persons on adequate mineral intake.

Interaction of dietary fibers with Vitamins absorption

Data on the effect of dietary fibers on vitamin in bioavailability is scarce. Vitamin A absorption appears to be increased with a formula diet containing guar, apple pectin, cellulose or bran.

Other related topics

1. What are the Dietary fibers?
2. Dietary fibers and related diseases
3. Bacterial flora and dietary fibers
4. Bile acids absorption and dietary fibers