Microminerals/Trace Elements• Minerals that comprise < 0.01% of the body weight

• Needed in concentrations of 1 PPM (part per million) or less; < 100 mg needed per day

• RDAs have been established for 6 of these elements

•Iron, zinc, copper, iodine, selenium, and molybdenum

• Adequate intakes have been estimated for three

•Manganese, fluoride, chromium

• Many are involved as cofactors in enzymes

Table 12-2, p. 419

Iron• Ferric (3+) and ferrous (2+) forms the only oxidation states found in the body and in food.

• Food forms are either heme or non-heme iron

• Heme forms (derived from hemoglobin and myoglobin) are found mostly in animal products

• Non-heme forms are principally found in plants and require more digestion prior to absorption; supplements are generally nonheme iron

• Many foods are fortified with iorn including flour, corn meal, and rice.

Fig. 12-2, p. 421

“Good” chelators:

Acids (ascorbic, citric, tartaric); sugars; meat products; mucin

“Inhibitors”: polyphenols such as those found in coffee and tea; oxalic acid; phytates; EDTA; calcium, zinc, manganese, nickel

p. 422

Storage = liver, bone marrow, spleen

Fig. 12-4, p. 426

Cellular iron influences the synthesis of apoferritin at the translation level.

Release of iron from stores requires mobilization of Fe3+ and the use of reducing substances such as riboflavin, niacin, and/or vitamin C .

Uptake by tissues depends on the transferrin saturation level and the presence of a tranferrin receptor (TfR2) on the cell

Fig. 12-5, p. 428

Functions:

•Energy Production

•In heme proteins - hemoglobin, myoglobin, cytochromes, In iron-sulfur proteins - several in electron transport chain, aconitase and ferrochelatase

•Other Enzymes

•monooxygenases, dioxygenases, and oxidases,

•aconitase (krebs cycle)

•Peroxidases

•oxidoreductases

•Ribonucleotide reductase

•Glycerolphosphate dehydrogenase

Fig. 12-6, p. 432

Daily needs cannot be met by absorbed iron. Therefore, it is highly conserved and recycled.

Losses are from GI tract, skin, kidney

Fig. 12-7, p. 433

Deficiency: Iron Deficiency and Iron Deficiency Anemia

Toxicity: Hemochromatosis or iron overload

Table 12-3, p. 436

Zinc

• Found in all organs and tissues; highest in bone, liver, kidney, muscle and skin

•Can exist in different valence states but in the body is always found in its divalent form (Zn2+)

•Found in many sources, but zinc from plant sources is lower in content and not as easily absorbed as Zn associated with meat.

Fig. 12-8, p. 438

Enhancers of absorption: citric acid, picolinic acid, histidine, cysteine, glutathione, low zinc status

Inhibitors: phytate, oxalate, polyphenols, fibers, folic acid, divalent cations

Fig. 12-10, p. 440

Table 12-4, p. 441

Carbonic anhydrase

Alkaline phosphatase

Alcohol dehydrogenase

Superoxide dismutase

Involved in at least 70 and probably as many as 200 different reactions. Is a part of more enzyme systems than all the other trace elements combined.

Table 12-5, p. 446

Fig. 12-12, p. 447

Fig. 12-13, p. 450

p. 451a

p. 451b

p. 452a

p. 452b

p. 452c

Fig. 12-14, p. 456

Fig. 12-15, p. 457

Fig. 12-16, p. 458

p. 459a

p. 459b

p. 459c

p. 460a

p. 460b

Fig. 12-17, p. 464

Fig. 12-18, p. 464

Fig. 12-19, p. 465

Fig. 12-20, p. 468

Fig. 12-21, p. 469

p. 470

Fig. 12-22, p. 470

Fig. 12-23, p. 471

p. 472

Table 12-6, p. 473

p. 474

Fig. 12-24, p. 478

p. 478

Fig. 12-25, p. 479

Fig. 12-25a, p. 479

Fig. 12-25b, p. 479

Table 12-7, p. 481

Table 12-1a, p. 418

Table 12-1, p. 418

Table 12-1b, p. 418