Nitrate, nitrite balance, and de novo synthesis of nitrate in humans consuming cured meats

Abstract

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.

Nitric oxide synthesis in patients with advanced HIV infection

“…Nitrate excretion is not affected by age or caloric intake. Nitrite intake analyses were included because nitrite is converted to nitrate before excretion in the urine [18].…”

Effect of Nitrate on Methane Production and Fermentation by Slurries of Human Faecal Bacteria

“…Whilst it is true that quantities of NO, are consumed in the diet (Walker, 1975;Knight et al, 1987) and that considerable levels are produced endogenously by the tissues (Lee et al, 1986), an accurate assessment of the role played by this metabolite requires detailed knowledge of how much actually becomes available to bacteria in the colon. Only then can the significance of NO, in the large gut fermentation be established.…”

“…Although this has been challenged by some workers (Bartholomew & Hill, 1984), 13N studies in rats and human NO, balance studies indicate that a further source of NO, results from endogenous formation in the tissues and that NO, is secreted into the gastrointestinal tract at several locations (Witter et al, 1979;Lee et al, 1986). Furthermore, recent work by Iyengar et al (1987) has shown that stimulated macrophages synthesize and secrete NO, and NO:.…”

Nitrate Analysis in Meats; Comparison of Two Methods

“…Most of those methods demonstrated superior sensitivity and precision over the standard calorimetric procedure (CdGriess). We have demonstrated that HPLC had superior accuracy and precision over classical methods for analyzing nitrate in foods (Schuster and Lee, 1987) and human metabolic samples (Lee et al, 1986).…”