Nutrition Science and Everyday Application - beta v 0.1

444 ALICE CALLAHAN, PHD, HEATHER LEONARD, MED, RDN, AND TAMBERLY POWELL, MS, RDN
Figure 8.3. The classification of minerals as either major minerals or trace minerals.
Minerals are water-soluble and do not require enzymatic digestion. They are absorbed
directly into the bloodstream, although some minerals need the assistance of transport
proteins for absorption and transport in blood.
Minerals are not as efficiently absorbed as most vitamins, and many factors influence their
bioavailability:
• Minerals are generally better absorbed from animal-based foods. Plant-based
foods often contain compounds that can bind to minerals and inhibit their
absorption (e.g., oxalates, phytates).
• In most cases, if dietary intake of a particular mineral is increased, absorption will
decrease.
• Some minerals influence the absorption of others. For instance, excess zinc in the
diet can impair iron and copper absorption. Conversely, certain vitamins enhance
mineral absorption. For example, vitamin C boosts iron absorption, and vitamin D
boosts calcium and magnesium absorption.
• As is the case with vitamins, mineral absorption can be impaired by certain
gastrointestinal disorders and other diseases, such as Crohn’s disease and kidney
disease, as well as the aging process. Thus, people with malabsorption conditions
and the elderly are at higher risk for mineral deficiencies.