Thursday, July 19, 2007

Part 2: Minerals: Bioavailability

The body varies in its capacity to absorb and use the minerals in food. For example, spinach contains considerable calcium, but only about 5% of it becomes absorbed. The same holds true for dietary iron, which the intestines absorbs with an average efficiency of 5 to 10%. Factors that affect the bioavailability of minreals in food include:

Type of food: The small intestine readily absorbs minerals contained in animal products because they do not contain plant binders and dietary fibers that hinder digestion and absorption.

Mineral-mineral interaction: Many minerals have the same molecular weight and hence competes for intestinal absorption. This makes it unwise to consume an excess of any one mineral.

Vitamin-mineral interaction: Various vitamins interact with minerals in a manner that affects mineral bioavailability. From a positive perspective, vitamin D facilitates calcium absorption, while vitamin C improves intestinal absorption of iron.

Fiber-mineral interaction: High fiber intake blunts the absorption of calcium, iron, magnesium, and phosphate by binding them and causing them to pass unabsorbed throught the digestive tract.

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