Effect of sodium nitrite on the bioavailability of meat iron for the anemic rat
Mahoney, A.W.; Hendricks, D.G.; Gillett, T.A.; Buck, D.R.; Miller, C.G.
Journal of Nutrition 109(12): 2182-2189
1979
ISSN/ISBN: 0022-3166 PMID: 512706 Document Number: 140338
During the curing of meat, added nitrite is converted to nitric oxide which covalently combines with the porphyrin bound Fe yielding the characteristic pink color of cured meat upon heating. Anemic rats were fed diets containing bologna prepared with different levels of nitrite to determine the effects of nitrite curing on the bioavailability of meat Fe. In experiment 1 the efficiency of converting meat Fe to Hb Fe was decreased from 58 to 39% and water extractable Fe decreased from 8.7 to 2.6 mg/kg bologna as sodium nitrite added to the bologna emulsion was increased from 0 to 50 ppm. The efficiency of converting meat Fe to Hb Fe tended to increase at sodium nitrite levels > 50 ppm. In experiment 2 the apparent absorption values were not decreased in response to adding sodium nitrite to the bologna emulsion but the efficiency of the conversion of absorbed meat Fe to Hb was clearly depressed. In experiment 3 addition of 12 mg nitrite per kg casein or bologna diet (an amount equivalent to the residual nitrite present in the high nitrite bologna) caused increased in the hematinic response. This is discussed in terms of nitrosylmethemoglobinemia and relative tissue hypoxia. The results of experiment 1 were confirmed in experiment 4. A very sensitive animal model showed that even very low levels of nitrite used in curing meat can have measurable physiological effects on the metabolism of meat Fe and very low levels of dietary nitrite from any source may be physiologically significant.