Effect of Atmospheric Oxidation on Bioavailability of Meat Iron and Liver Weights in Rats

Abstract

Iron bioavailability of diets containing oxidized turkey and oxidized beef meat was investigated in two experiments. Lyophilized, uncooked turkey meat and beef meat were allowed to oxidize at room temperature. In experiment 1, rats were made anemic and fed diets containing uncooked lyophilized turkey meat which had been exposed to air for 0, 48, 96, 144, 216 or 264 hours. In experiment 2, anemic rats were fed diets composed of basal, basal + iron, basal + iron + formaldehyde, 100% fresh beef, 75% fresh-25% oxidized beef, 50% fresh-50% oxidized beef, 25% fresh-75% oxidized beef, 100% oxidized beef and 100% fresh beef + formaldehyde. The diets were prepared so that meat was the only source of iron. Hemoglobin regeneration served as the basis for measuring iron utilization. The length of oxidation time of the turkey meat did not significantly affect the growth of the rats or the bioavailability of the meat iron. Rats fed severely oxidized beef diets had decreased body weight, enlarged livers and depressed hematinic responses. Formaldehyde did not significantly affect iron utilization in rats fed basal diets, but depressed liver iron storage in rats fed fresh beef.

Bioavailability of Iron to rats from nitrite and erythorbate cured processed meats

“…In this study rats utilized total heme and nonheme iron in the meat-based diets (uncured, +E, +N, and +E+N) less efficiently than the nonheme iron in the control diet (L+Fe). This is consistent with other studies, which have shown the absorption of iron from ferrous sulfate by the anemic rat was much greater than the absorption of iron from meats (Cardón et al, 1980;Farmer et al, 1977; Mahoney et al, 1974Mahoney et al, ,1979Rotruck and Luhrsen, 1979). This is in contrast to that observed for humans, who absorb the iron from meat better than from ferrous sulfate iron (Layrisse et al, 1973).…”

“…A TBA of 19.5 mg/kg was reported for the uncured meat in the study of Mahoney et al (1979). In addition, it was later shown that the degree of rancidity must be very high before a significant depression in hematinic response was noted, e.g., 14 days at 21 °C in air (Cardón et al, 1980).…”

Efficiency of Hemoglobin Regeneration as a Method of Assessing Iron Bioavailability in Food Products

“…Residual nitrite was associated with an apparent increase in iron bioavailability, which was explained on the basis of some nitric oxide binding to hemoglobin, rendering a fraction of it unable to carry oxygen and thus stimulating hematopoiesis. Severe atmospheric oxidation of beef results in depressed iron bioavailability and growth in rats while similar oxidation of turkey meat did not (Cardon et al, 1980). Based on the limited data available, the relative biological values of iron sources are similar whether determined by the slope-ratio assay or by efficiency of conversion of dietary iron into hemoglobin (Table 3).…”

Comments on bioavailability of iron to rats from nitrite and erythorbate cured processed meats

“…Variability in this single experiment must have been rather large since a mean difference of 19% efficiency of converting ingested iron to hemoglobin was not statistically significant. Others (Mahoney et al, 1979;Park et aL, 1983; Cardón et al, 1980) find that much smaller mean differences for this parameter are statistically significant. A single experiment using 36 rats divided among six treatments with the experimental variability reported in this paper is not, in our opinions, a rigorous test of the effects of curing with nitrite and erythorbate on the bioavailability of iron in cured meat.…”