Nitrate balance was measured in nine men consuming a fixed daily diet with constant nitrate (570 mumol/day), varying nitrite (18 to 150 mumol/day), and varying erythorbate levels. Nitrite and erythorbate were added to meat that was then cured and frozen until consumption. All diets were consumed by each subject for 17 days each. Average daily urinary nitrate excretion ranged from 959 to 2382 mumol/day. Subjects excreted significantly more nitrate in urine when fed nitrite cured meats with or without erythorbate than when fed uncured meat (1617 and 1577 versus 1430 mumol nitrate/day, respectively). The amount of nitrate excreted in urine consistently exceeded intakes of nitrate and nitrite by an average 870 mumol/day. This excess represented endogenous synthesis by subjects and was not due to unmeasured nitrate in the diet. The commonly used Greiss and xylenol procedures were unable to measure all nitrate in urine and in diets when compared to high performance liquid chromatographic analyses. The Greiss and xylenol analyses underestimated nitrate synthesis by 220 and 150 mumol/day, respectively when results were not adjusted by determining recovery of added nitrate.
Nine adult males consumed a constant mixed diet containing 200 g of processed meat for 51 days. The processed meats fed were uncured sausage (uncured), sausage cured with nitrite (156 µg of nitrite/g of meat) (+N), and sausage cured with nitrite (156 µg of nitrite/g of meat) and erythorbate (550 µg of erythorbate/g of meat) (+E+N). Sausage +E+N was typical of commercial formulations. The dietary treatments had no significant effects on apparent absorption of iron, zinc, or copper, serum zinc or copper levels, or plasma ferritin, transferrin, and ceruloplasmin levels. It is unlikely that commercial curing processes adversely affect the bioavailability of minerals in the meat.We studied the effects of nitrite curing of meat on the bioavailability of iron, zinc, and copper to human subjects for several reasons. First, approximately one-third of all meat consumed in the United States is cured with nitrite (Goyan and Foreman, 1980). Second, meat products are a major source of dietary zinc and iron for many Americans. Approximately 34% of the iron consumed by Americans participating in the Nationwide Food Consumption Survey was supplied by meat, fish, and poultry products (Science and Education Administration, 1980). Welsh and
The bioavailability of zinc and copper from meats cured with erythorbate and/or nitrite was evaluated. Iron-depleted rats were fed six test diets that contained as protein sources: uncured meat, meat cured with erythorbate, meat cured with nitrite, meat cured with nitrite and erythorbate, lactalbumin, and lactalbumin supplemented with iron to the levels present in the meat-based diets. All diets contained similar levels of zinc and copper. Treatment of the meat with usual commercial levels of nitrite (156 μg/g meat) and/or erythorbate (550 μg/g meat) had no significant effect on zinc and copper utilization by rats. However, rats fed meat-based diets retained more zinc and copper in their livers than rats fed lactalbumin-based diets.
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