Zinc, and Selenium

After sodium, potassium, and calcium, Mg is the most abundant body cation and the second most prevalent intracellular cation after potassium. Only about 3% of total body Mg is present in the extracellular fluids approximately 57% is in bone 

Although serum Mg levels are probably not age-related per se, Touitou et al. (T8) reported that hypomagnesemia is common in the elderly. They measured both serum and erythrocyte Mg levels in 381 unselected healthy elderly men and women, most of whom were older than 75 years. They found that 10% of these individuals had decreased serum levels however, 20% had low red cell levels. This latter finding is particularly important, since it is a more accurate measure of total body Mg. In this regard, the current minimum recommended daily Mg intake is 350 100 mg. It is estimated that prior to the Industrial Revolution, the average intake was 450-500 mg/day. Currently, however, the average adult intake in the United States is only 175-225 mg (A6). 

Numerous studies have shown that hypo- and hypermagnesemia are common and of considerable importance in various cardiac dysrhythmias, myocardial infarction, increased overall mortality, diabetes mellitus, among others (K13). 

Signs/Symptoms Zinc Deficiency versus Aging 

Plasma zinc levels are commonly decreased in the elderly (Gil). These authors reported mean ( SD) plasma levels in normal young adults at 12.7 ( 1.4) mmol/liter versus 10.5 ( 4.7) mmol/liter in the elderly intracellular levels (neutrophils) were 1.26 ( 0.28) and 0.95 ( 0.26) nmol/mg protein, respectively. This deficiency is most often due to lack of dietary lean meat, poultry, and fish. As a result, zinc intake is frequently less than the minimum recommended intake of 15 mg/day. Moreover, Zn deficiency is particularly common in individuals with diabetes mellitus, liver and renal diseases, malabsorption, alcohol abuse, and those taking diuretic medications (K13). Interestingly, many of the signs and symptoms of Zn deficiency are the same as those often attributed to the aging process (Table 3). 

---

Trace elements Provide standard parenteral trace element preparation (containing zinc, copper, manganese, chromium, and selenium) daily in PN Assess patient for any possible adjustments needed (e.g., delete copper and manganese from PN if the patient has evidence of severe cholestasis, supplemental zinc and selenium for any Gl or fistula losses) or potential deficiencies... 

Polymeric network structures of zinc and selenium with A.A -ethylenediamine have been formed and structurally characterized. The tetrahedral zinc centers are Se3N coordinated with the diamine bridging to give two-dimensional slabs 586... 

FIG. 16. Zinc and selenium coverages, per cycle, after four ECALE cycles, as a function of the potential used to deposit zinc. The Se atomic layers were formed by first depositing a couple of monolayers of Se at —0.9 V and then reducing off the excess at —0.9 V in the corresponding blank electrolyte solution. 

Bettger, W. J. (1993). Zinc and selenium, site-specific versus general antioxidation. Can. J. Phys. Pharmacol. 71, 721-724. 

The 5-deiodinase enzyme activity necessary for liver conversion of T-4 into T-3 requires adequate levels of zinc and selenium. During calorie restricted periods lasting more than 2-3 weeks T-4 conversion to the more active T-3 decreases dramatically greatly reducing fat loss. Adequate zinc intake and absorption prevents the decline in 5-deiodinase that causes this negative by about 67% and adequate selenium levels prevents the decline by about 47%. Obviously both in sufficient amounts are best. 

---