Zinc
From IKE
to identify zinc as an essential crosslinking or coordinating factor in many proteins and enzymes
to identify phytate as an inhibitory factor for zinc (and other divalent metal) absorption and why
Contents |
Basics
- Plays a structural and coordinating role in >250 proteins, particularly enzymes
- It is convenient to think of zinc as a growth factor, like protein
- Many proteins would be non-functional without zinc
Role
- Because zinc-containing enzymes come from all six classes, there are very major effects in Zinc deficiency
- Tissues that turnover rapidly (marrow, intestines, skin, hair) are easily affected
- Skin eruptions are common (sometimes superinfected by bacteria and yeasts)
- Adequate Zn nutrition is essential for growth and development (sexual development in males)
- Within cells several metals, copper included, are bound to a ubiquitous protein called metallothionein (MT)
Dietary Sources
- Body content: 2-2.5g
- Recommended intake: 5-15mg/day
- Zinc is absorbed easily throughout the small intestine
- like iron, it is affected by some plant food constituents (principally phytate [inositol phosphate] and fiber)
Deficiency
- rare because the metal is ubiquitous
- Zinc excretion plays an important role in keeping balance
- Major route: pancreas and small intestine (not bile)
- Minor route: kidney (increased in alcoholics)
- Poorly available from plant foods
- The phytate (inositol hexaphosphate) and fiber contents of foods bind Zn and prevent its absorption
- Unleavened bread (no yeast) and soy products contain phytate
- Yeast contains an enzyme, phytase, which destroys phytate.
