Nitrates, nitrites and N-nitrosocompounds: a review of the occurrence in food and diet and the toxicological implications

Volatile N-nitrosamines in processed meat products: An approach for monitoring dietary exposure, assessing human risk, and evaluating variable correlations by principal component analysis and heat map

Several epidemiological studies have reported a positive association between the consumption of processed meats containing N-nitrosamines (NAs) and the incidence of hepatocellular and colon cancer. The health risk assessment in this investigation was based on the concentration of six volatile N-nitrosamines (VNAs) (N-nitrosodimethylamine, N-nitrosodiethylamine, N-nitrosomethylethylamine, N-nitrosopiperidine, N-nitrosodibutylamine, and N-nitrosodi-n-propylamine) found in processed meat products (sausage and kielbasa) in the Iranian market. Direct supported liquid membrane two-phase hollow fiber electromembrane extraction coupled to gas chromatography/mass spectrometry was used to analyse six VNAs. The mean concentration of the six VNAs in sausages and kielbasa was 38.677 ± 27.56 and 48.383 ± 35.76 μg/kg, respectively. The 95th percentile for the chronic daily intake of total VNAs for children (3-14 years) and adults (15-70 years) were calculated to be 5.06 × 10-4 and 1.09 × 10-4 mg/kg bw/day, respectively. The cancer risk assessment showed that the risk associated with NDEA was the highest among the other VNAs studied in Iranian processed meat, with a 95th percentile for the child and adult groups. Based on an incremental lifetime cancer risk (ILCR) value of ≤10-4 for the carcinogenic effects of exposure to a total of six VNAs, it indicates low concern for all age groups.

Effective removal of Allura red food dye from water using cross-linked chitosan-diatomite composite beads

Chitosan (Ch)-diatomite (D) composite beads (Ch-D) were synthesized using epichlorohydrin and tripolyphosphate crosslinkers and then moulded into uniform beads in tripolyphosphate solution. FT-IR and SEM-EDX analyses showed that Ch-D composite adsorbent was successfully synthesized by functionalization of chitosan to Ch-D by hydrogen bonding and electrostatic interactions and improved adsorption capacity for removal of Allura red AC (AR) food dye. The removal rate of AR food dye was found to be 98 % at 25 °C, natural AR dye pH value, 24 h, and at the initial AR dye concentration of 200 mg L-1. The maximum adsorption capacity was found to be 34.7 mg g-1. It was observed that π-π interactions, hydrogen bonds, and electrostatic interactions between the functional groups containing oxygen and amine on the surface of the Ch-D composite and the functional groups of the anionic AR dye, and AR dye adsorption via complexation took place. In light of all this information, the Ch-D composite adsorbent is a promising potential material for the effective treatment of colored pollutants from wastewater.

New insights into the biology and development of lung cancer in never smokers-implications for early detection and treatment

Lung cancer is the leading cause of cancer deaths worldwide. Despite never smokers comprising between 10 and 25% of all cases, lung cancer in never smokers (LCNS) is relatively under characterized from an etiological and biological perspective. The application of multi-omics techniques on large patient cohorts has significantly advanced the current understanding of LCNS tumor biology. By synthesizing the findings of multi-omics studies on LCNS from a clinical perspective, we can directly translate knowledge regarding tumor biology into implications for patient care. Primarily focused on never smokers with lung adenocarcinoma, this review details the predominance of driver mutations, particularly in East Asian patients, as well as the frequency and importance of germline variants in LCNS. The mutational patterns present in LCNS tumors are thoroughly explored, highlighting the high abundance of the APOBEC signature. Moreover, this review recognizes the spectrum of immune profiles present in LCNS tumors and posits how it can be translated to treatment selection. The recurring and novel insights from multi-omics studies on LCNS tumor biology have a wide range of clinical implications. Risk factors such as exposure to outdoor air pollution, second hand smoke, and potentially diet have a genomic imprint in LCNS at varying degrees, and although they do not encompass all LCNS cases, they can be leveraged to stratify risk. Germline variants similarly contribute to a notable proportion of LCNS, which warrants detailed documentation of family history of lung cancer among never smokers and demonstrates value in developing testing for pathogenic variants in never smokers for early detection in the future. Molecular driver subtypes and specific co-mutations and mutational signatures have prognostic value in LCNS and can guide treatment selection. LCNS tumors with no known driver alterations tend to be stem-like and genes contributing to this state may serve as potential therapeutic targets. Overall, the comprehensive findings of multi-omics studies exert a wide influence on clinical management and future research directions in the realm of LCNS.

Sodium nitrite poisoning: A series of 20 fatalities in which post-mortem blood nitrite and nitrate concentrations are reported

Sodium nitrite has several industrial applications however its accidental or intentional ingestion has been associated with severe toxicity and death. We present a series of 20 cases over 2 years in which evidence of sodium nitrite ingestion was found at the scene and supported by biochemical analysis of post-mortem blood nitrite and nitrate levels. Routine toxicological screening was performed on post-mortem blood samples received at University Hospitals of Leicester (UHL) NHS Trust, including ethanol analysis by headspace gas chromatography-flame ionisation detection (HS GC-FID), drug screening by high resolution accurate mass-mass spectrometry (HRAM-MS) and confirmatory drug quantitation by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Cases in which the history indicated the possibility of nitrite salts present at the scene, purchase of a suicide kit or a dusky-ash appearance of skin on post-mortem were referred to a specialist laboratory for nitrite and nitrate analysis. Analysis was based upon the gas-phase chemiluminescent reaction between nitric oxide (NO) and ozone; NO levels were determined using an NOA 280A, Sievers NO analyser. Twenty post-mortem cases in which sodium nitrite ingestion was the most probable cause of death were reported between January 2020 and February 2022; mean age was 31 years (range 14-49) with 9/20 (45%) female. 16/20 (80%) of cases had a history of depression and / or mental health issues. In half of the cases, anti-depressant / anti-psychotic drugs were prescribed; these drugs were detected in 8/20 (40%) cases. Ethanol was detected in 4/20 (20%) cases and anti-emetic drugs in 7/20 (35%) cases; anti-emetic drugs may be used to aid retention of sodium nitrite. Illicit drugs (amphetamine, cannabis and cocaine) were present in 3/20 cases (15%). Nitrite was found to be elevated in all but one case (95%), and nitrate was elevated in 17/20 (85%) cases. This paper highlights a surge in numbers of deaths across England and Wales due to sodium nitrite toxicity. Although, nitrite poisoning remains a rare cause of death, it is worthwhile considering its use in individuals with suicidal ideation given its unregulated availability online. The detection and quantitation of nitrite and nitrate requires specialised, highly reliable methodology currently only available in research laboratories. Implication of sodium nitrite ingestion also relies heavily upon circumstantial evidence combined with quantification. The provision of a quantitative nitrite / nitrate analytical service greatly assists in determining the cause of death in these cases.

Estimating nitrate intake in the Australian diet: Design and validation of a food frequency questionnaire

BACKGROUND

Dietary nitrates may play a role in mediating several key physiological processes impacting health and/or exercise performance. However, current methods for assessing dietary nitrate (NO3 - ) consumption are inadequate. The present study aimed to examine the dietary nitrate intake in a sample of 50 healthy adults, as well as test the validity of a purposefully developed food frequency questionnaire (FFQ).

METHODS

Dietary nitrate intake was estimated over a week using (i) three 24-h dietary recalls; (ii) a short-term (7-day) FFQ; and (iii) a biomarker (urinary nitrate), in conjunction with a nitrate reference database.

RESULTS

Daily dietary nitrate intake estimates were 130.94 mg (average of three 24-h recalls) and 180.62 mg (FFQ). The mean urinary NO3 - excretion was 1974.79 µmol day-1 (or 917.9 µmol L-1 ). Despite the difference between the two dietary assessment methods, there was a moderate positive correlation (r = 0.736, ρ < 0.001) between the two tools. There was also a positive correlation between urinary NO3 - and 24-h recall data (r = 0.632, ρ < 0.001), as well as between urinary NO3 - and FFQ (r = 0.579, ρ < 0.001).

CONCLUSIONS

The ability to accurately estimate nitrate intakes depends on having suitable reference methods to estimate the concentrations of nitrate in the food supply, coupled with valid and reliable dietary assessment tools. Based on the findings from the present study, at an individual level, dietary recalls or records may be more accurate in estimating intakes of NO3 - . However, given the lower cost and time needed for administration relative to recalls, the FFQ has merit for estimating NO3 - intakes in health interventions, dietary surveys and surveillance programs.

Patterning Wettability for Open-Surface Fluidic Manipulation: Fundamentals and Applications

Effective manipulation of liquids on open surfaces without external energy input is indispensable for the advancement of point-of-care diagnostic devices. Open-surface microfluidics has the potential to benefit health care, especially in the developing world. This review highlights the prospects for harnessing capillary forces on surface-microfluidic platforms, chiefly by inducing smooth gradients or sharp steps of wettability on substrates, to elicit passive liquid transport and higher-order fluidic manipulations without off-the-chip energy sources. A broad spectrum of the recent progress in the emerging field of passive surface microfluidics is highlighted, and its promise for developing facile, low-cost, easy-to-operate microfluidic devices is discussed in light of recent applications, not only in the domain of biomedical microfluidics but also in the general areas of energy and water conservation.

Nitrate, nitrite and nitrosamines in the global food supply

Inorganic nitrate provided by either nitrate salts or food supplements may improve cardiometabolic health. However, current methods to assess dietary nitrate, nitrite and nitrosamine consumption are inadequate. The purpose of this study was to develop a reference database to estimate the levels of nitrate, nitrite and nitrosamines in the global food supply. A systematic literature search was undertaken; of the 5,747 articles screened, 448 met the inclusion criteria. The final database included data for 1,980 food and beverages from 65 different countries. There were 5,105 unique records for nitrate, 2,707 for nitrite, and 954 for nitrosamine. For ease of use, data were sorted into 12 categories; regarding nitrate and nitrite concentrations in food and beverages, 'vegetables and herbs' were most reported in the literature (n = 3,268 and n = 1,200, respectively). For nitrosamines, 'protein foods of animal origin' were most reported (n = 398 records). This database will allow researchers and practitioners to confidently estimate dietary intake of nitrate, nitrite and nitrosamines. When paired with health data, our database can be used to investigate associations between nitrate intake and health outcomes, and/or exercise performance and could support the development of key dietary nitrate intake guidelines.

Real-Time High-Sensitivity Reaction Monitoring of Important Nitrogen-Cycle Synthons by 15N Hyperpolarized Nuclear Magnetic Resonance

Here, we show how signal amplification by reversible exchange hyperpolarization of a range of ¹⁵N-containing synthons can be used to enable studies of their reactivity by ¹⁵N nuclear magnetic resonance (NO₂^– (28% polarization), ND₃ (3%), PhCH₂NH₂ (5%), NaN₃ (3%), and NO₃^– (0.1%)). A range of iridium-based spin-polarization transfer catalysts are used, which for NO₂^– work optimally as an amino-derived carbene-containing complex with a DMAP-d₂ coligand. We harness long ¹⁵N spin-order lifetimes to probe in situ reactivity out to 3 × T₁. In the case of NO₂^– (T₁ 17.7 s at 9.4 T), we monitor PhNH₂ diazotization in acidic solution. The resulting diazonium salt (¹⁵N-T₁ 38 s) forms within 30 s, and its subsequent reaction with NaN₃ leads to the detection of hyperpolarized PhN₃ (T₁ 192 s) in a second step via the formation of an identified cyclic pentazole intermediate. The role of PhN₃ and NaN₃ in copper-free click chemistry is exemplified for hyperpolarized triazole (T₁ < 10 s) formation when they react with a strained alkyne. We also demonstrate simple routes to hyperpolarized N₂ in addition to showing how utilization of ¹⁵N-polarized PhCH₂NH₂ enables the probing of amidation, sulfonamidation, and imine formation. Hyperpolarized ND₃ is used to probe imine and ND₄⁺ (T₁ 33.6 s) formation. Furthermore, for NO₂^–, we also demonstrate how the ¹⁵N-magnetic resonance imaging monitoring of biphasic catalysis confirms the successful preparation of an aqueous bolus of hyperpolarized ¹⁵NO₂^– in seconds with 8% polarization. Hence, we create a versatile tool to probe organic transformations that has significant relevance for the synthesis of future hyperpolarized pharmaceuticals.

Nutrient and Nitrate Composition of Greenhouse-Grown Leafy Greens: A Trial Comparison Between Conventional and Organic Fertility Treatments

Arugula (Eruca sativa), mizuna (Brassica rapa var. nipponsinca), red giant mustard (Brassica juncea), and spinach (Spinaciaoleracea “Tyee”) are fresh produce crops high in nutritive value that provide shortfall and high interest nutrients addressed in the U.S. Dietary Guidelines. The primary objective of this project was to evaluate fertility treatments unique to these crops that optimize their nutritional capacity. Measurements discussed include: vitamin C, dietary fiber, calcium, iron, potassium, sodium, and nitrate. Plants were grown at the University of Minnesota St. Paul Campus (St. Paul, MN) in a greenhouse from November to April under an 18 h photoperiod and a 24/13°C day/night temperature. Plants were grown using five different fertility treatments, including four organic treatments and one conventional control. The plant treatment combinations were replicated three times and the entire experiment was duplicated. Fertility treatments had a high impact on vitamin C (with over a 3-fold difference in treatments in the first experiment), nitrate (over 10-fold difference among fertility treatments in some species) and potassium concentrations (over 5-fold difference among fertility treatments in some species) in analyzed plant tissue. No consistent differences were found for fiber, calcium, iron and sodium concentrations in tissue analyzed. This is the first study to analyze the impact that different organic treatments can have on multiple nutrients and compounds addressed by the U.S. Dietary Guidelines for high-impact, highly-consumed produce crops.

Nutritional and functional compounds in dahlia flowers and roots

Abstract The use of unconventional edible plants in human food has grown more widespread in recent years, driven mainly by gourmet dishes. Evidence of the food properties of these species is still scarce. Aiming to obtain more in-depth knowledge of dahlia plants, this study aimed to evaluate the nutritional, bioactive, and antinutritional properties of the edible parts of purple dahlia (tuberous root and flower) to elucidate their value and safety as foods. The percent composition, caloric value, pH, Total Soluble Solids (TSS), Total Titratable Acidity (TTA), ratio of TSS to TTA, anthocyanins, carotenoids, vitamin C, total phenolics, tannins, nitrates, and minerals of the roots and flowers were analyzed. The inulin content in the root and the color of the flower were also evaluated. The results were reported as mean and standard deviation, and exploratory factor analysis was performed. Both parts of the dahlia had constituents that contribute to a good diet at concentrations like those in conventional vegetables, whereas the antinutritional components were also compatible with those of commonly consumed foods, with acceptable dietary values. Thus, it is evident that purple dahlia flowers and roots have potential for use in human food and can be considered good options to improve and diversify a healthy diet.

Potential health risks of toxic heavy metals and nitrate via commonly consumed bivalve and vegetable species in Ho Chi Minh City, Vietnam

This study aimed to evaluate the health risks of cadmium (Cd), lead (Pb), inorganic arsenic (As), and nitrate exposure through the consumption of bivalves and vegetables collected from local markets in Ho Chi Minh City. The present study analyzed four favorite bivalve species (Meretrix lyrate; Perna viridis; Anadara subcrenata; Anadara granosa) for concentrations of Cd, Pb, and inorganic As and 9 vegetable species (Brassica juncea; Brassica integrifolia; Brassica rapa chinensis; Nasturtium officinale; Lactuca sativa; Ipomoea aquatica; Amaranthus gangeticus; Ipomoea batatas; Spinacia oleracea) for concentrations of Pb and nitrate. The target hazard quotient (THQ) and target cancer risk (TR) were calculated to estimate non-carcinogenic and carcinogenic health risks, respectively. For bivalves, Cd and inorganic As were present at relatively lower concentrations, whereas a relatively higher accumulation of Pb was recorded. The THQ for Cd, Pb, or inorganic As was below the threshold of 1, suggesting no potential health risks. In the case of vegetables, Pb was present at relatively low concentrations, while nitrate accumulation was at relatively high concentrations. The THQ for nitrate was higher than the threshold of 1, suggesting a potential health risk. The combined effects are estimated according to the hazard index (HI), which shows the health risks associated with the consumption of these bivalves and vegetable species. Therefore, continuous and excess consumption for a lifetime of more than 70 years has a probability of target cancer risk.

Ultrasound intensification of Ferrochelatase extraction from pork liver as a strategy to improve ZINC-protoporphyrin formation

The enzyme Ferrochelatase (FeCH), which is naturally present in pork liver, catalyses the formation of Zinc-protoporphyrin (ZnPP), a natural pigment responsible for the typical color of dry-cured Italian Parma ham. The aim of this study was to evaluate the feasibility of using high power ultrasound in continuous and pulsed modes to intensify the extraction of the enzyme FeCH from pork liver. US application during FeCH extraction led to an improved enzymatic activity and further increase in the formation of ZnPP. The optimal condition tested was that of 1 min in continuous US application, in which time the enzymatic activity increased by 33.3 % compared to conventional extraction (30 min). Pulsed US application required 5 min treatments to observe a significant intensification effect. Therefore, ultrasound is a potentially feasible technique as it increases the catalytic activity of FeCH and saves time compared to the conventional extraction method.

Review of potential risks associated with supplemental dietary exposure to nitrate-containing compounds in swine-a paradox in light of emerging benefits

Calcium nitrate has been reported to benefit reproductive outcomes in sows and their offspring when administered via the feed (15 to 19 mg/kg-body weight [bw]/day) during the periparturient period. Traditionally, dietary nitrate had been considered a methemoglobinemia (MetHb) risk in swine. Similar hazard concerns have existed in humans, but a recent benefit/risk analysis established that nitrate levels associated with well-recognized health benefits outweigh potential risks. A similar benefit/risk perspective in swine was lacking and challenged by sparse published hazard data, often referenced within larger reviews related to all livestock. The objective of this review was to better characterize the potential for adverse health and performance effects reported in the literature for swine consuming nitrate and to provide metrics for evaluating the reliability of the studies reviewed. Supplemental exposure via feed or drinking water was considered for any life stage, dose, and exposure duration. More than 30 relevant studies, including case reports and reviews, examined calcium, potassium, sodium, or unspecified nitrate salts at doses up to 1,800 mg nitrate/kg-bw/day for exposures ranging from 1 to 105 d. The studies primarily evaluated weight gain, blood methemoglobin levels, or vitamin A homeostasis in sows or growing swine. An extensive review of the literature showed reports of adverse effects at low nitrate doses to be of low reliability. Conversely, reliable studies corroborate nitrate intake from feed or drinking water at levels equal to or greater than the European Food Safety Authority's no-observed-adverse-effect level (NOAEL) for swine of 410 mg nitrate/kg-bw/day, with no MetHb or other adverse effects on reproduction, growth, or vitamin A levels. Using a weight-of-evidence evaluation, we have moderate-to-high confidence that the NOAEL for nitrate supplementation in swine is likely between 600 and 800 mg/kg-bw/day. These levels are several-fold higher than dietary nitrate concentrations (19 mg/kg-bw/day) that are known to benefit birth outcomes in sows. This review elucidates the quality and reliability of the information sources historically used to characterize nitrate in swine feed as a contaminant of concern. Results from this evaluation can assist risk managers (e.g., regulatory officials and veterinarians) in consideration of proposed benefits as well as reassuring swine producers that low-level nitrate supplementation is not anticipated to be a concern.

Drinking water nitrosamines in a large metropolitan region in Brazil

Nitrosamines are a concerning group of carcinogens, which have gained increasing attention over the last years, frequently found in drinking and recycled water systems. In this work, an analytical method was developed for the detection and quantification of seven nitrosamines (NDMA, NMEA, NPYR, NDEA, NPIP, NDPA, and NDBA) in drinking water. The method is based on gas chromatography coupled with a single quadrupole mass spectrometer (GC-MS) with electron ionization (EI) mode. Sample enrichment and matrix cleanup by solid-phase extraction (SPE) were performed using the US EPA Method 521 cartridge packed with coconut-based charcoal. The simple method allowed reliable identification and quantification of nitrosamines in the water at nanogram per liter levels. The optimized method was validated at three concentration levels (20, 100, and 200 ng L-1) in ultrapure and drinking water samples. Average recoveries were 63-87% for ultrapure water and 38-79% for drinking water with relative standard deviations (RSD) below 10% for both matrices. Method detection limits were 1.23-3.14 ng L-1. The described method was applied to eighteen drinking water samples collected from 13 cities of the Metropolitan Region of Campinas (São Paulo, Brazil). NDMA was the most frequent nitrosamine detected (89% of samples) and had the highest concentration level found (67 ng L-1). The levels of nitrosamines found in drinking water samples are of considerable relevance since the selected area is a major urban center that has amply expanded industrial and agricultural activities over the last few decades. To the best of our knowledge, this is the first evaluation of nitrosamines in drinking water conducted in Brazil to date.

Use of real-time sensors for compliance monitoring of nitrate in finished drinking water

Across the Midwestern United States, Public Water Systems (PWSs) struggle with high levels of nitrate in source waters from intense agricultural activity. Leveraging a sensor network deployed across Iowa surface waters, we evaluated the potential of the Hach Nitratax SC Plus, which uses UV-light absorption to quantify dissolved nitrate-nitrite (NO_x-N) down to 0.1 mg-N L^-1, for real-time monitoring of NO_x-N in drinking water. For six different PWSs over multiple years, we compare NO_x-N levels in source waters (surface and groundwater under surface influence) to those measured via traditional methods (e.g., ion chromatography (IC)) for US EPA compliance monitoring. At one large PWS, we also evaluated sensor performance when applied to near-finished drinking water (filter effluent). We find good agreement between traditional analytical methods and in situ sensors. For example, for 771 filter effluent samples from 2006-2011, IC analysis averaged NO_x-N of 5.8 mg L^-1 while corresponding sensor measurements averaged 5.7 mg L^-1 with a mean absolute error of 0.23 (5.6%). We identify several benefits of using real-time sensors in PWSs, including improved frequency to capture elevated NO_x-N levels and as decision-support tools for NO_x-N management.

Vitamin C and nitrates contents in fruit and vegetables from farmers' markets and supermarkets

Fruits and vegetables are the best food sources of vitamin C. However, fruits and vegetables can be also sources of potentially harmful substances to the human body, nitrates being one of these. The aim of this study was to compare vitamin C and nitrates contents in selected fruits and vegetables from supermarkets and local farmers' markets. Samples of plums, strawberries, apples, spinach, red peppers and tomatoes were chosen for analysis. Content of vitamin C and nitrates was analyzed by HPLC/DAD. The hypothesis was that local market fruits and vegetables contain more vitamin C and fewer nitrates than samples bought in supermarkets. Laboratory analyses showed that there were differences in vitamin C in the case of strawberries, tomatoes and red peppers. The highest level of ascorbic acid was in red pepper samples (141 mg.100g-1). In the case of fruit, the highest content was in strawberries (70 mg.100g-1). As far as nitrates content is concerned, in three cases out of six, the fruit and vegetables we tested from farmers' markets contained lower concentrations of nitrates than those purchased at supermarkets and the hypothesis was accepted in these cases. There was no significant difference between the nitrate content of the local market and supermarket strawberries and red peppers. Tomatoes had significantly higher nitrate content when purchased at farmers' markets than at supermarkets. Leafy vegetables are considered to be the major source of nitrates, and this was confirmed by this study. The highest content of nitrates was in the spinach sample (2969 mg.kg-1). Among all fruit samples, strawberries had the highest nitrates levels (maximum 131 mg.kg-1). The results of this work showed that the content of ascorbic acid and nitrates differs significantly depending on the type of fruit or vegetables.

Water Quality for Grazing Livestock I

Water is the most important nutrient for rangeland livestock. However, competition with municipalities, industry, and other water users often results in grazing livestock being forced to use water supplies that are less than perfect. Surface water in western rangleands are often contaminated by mineral extraction, irrigation runoff and other human activities. Mineral contaminants in drinking water are additive with similar contaminants in feedstuffs. The goal of this and the subsequent article is to provide producers and veterinarians with the basic background to make informed decisions about whether a given water supply is "safe" for livestock.

Nitrated meat products are associated with mania in humans and altered behavior and brain gene expression in rats

Mania is a serious neuropsychiatric condition associated with significant morbidity and mortality. Previous studies have suggested that environmental exposures can contribute to mania pathogenesis. We measured dietary exposures in a cohort of individuals with mania and other psychiatric disorders as well as in control individuals without a psychiatric disorder. We found that a history of eating nitrated dry cured meat but not other meat or fish products was strongly and independently associated with current mania (adjusted odds ratio 3.49, 95% confidence interval (CI) 2.24-5.45, p < 8.97 × 10^-8). Lower odds of association were found between eating nitrated dry cured meat and other psychiatric disorders. We further found that the feeding of meat preparations with added nitrate to rats resulted in hyperactivity reminiscent of human mania, alterations in brain pathways that have been implicated in human bipolar disorder, and changes in intestinal microbiota. These findings may lead to new methods for preventing mania and for developing novel therapeutic interventions.

Modulation of N-Methyl-N-nitrosourea Mutagenesis in Mouse Embryo Fibroblasts Derived from the gpt Delta Mouse by an Inhibitor of the O6-Methylguanine Methyltransferase, MGMT

DNA methylating agents are abundant in the environment and are sometimes used in cancer chemotherapy. They react with DNA to form methyl-DNA adducts and byproduct lesions that can be both toxic and mutagenic. Foremost among the mutagenic lesions is O6-methylguanine (m6G), which base pairs with thymine during replication to cause GC → AT mutations. The gpt delta C57BL/6J mouse strain of Nohmi et al. (Mol. Mutagen 1996, 28, 465-70) reliably produces mutational spectra of many DNA damaging agents. In this work, mouse embryo fibroblasts (MEFs) were made from gpt delta C57BL/6J mice and evaluated as a screening tool to determine the qualitative and quantitative features of mutagenesis by N-methyl-N-nitrosourea (MNU), a direct-acting DNA alkylator that serves as a model for environmental N-nitrosamines, such as N-nitrosodimethylamine and therapeutic agents such as Temozolomide. The DNA repair protein MGMT (O6-methylguanine DNA methyltransferase) protects against environmental mutagenesis by DNA methylating agents and, by removing m6G, limits the therapeutic potential of Temozolomide in cancer therapy. The gpt delta MEFs were treated with MNU to establish dose-dependent toxicity. In parallel, MNU mutagenicity was determined in the presence and absence of the MGMT inhibitor AA-CW236 (4-(2-(5-(chloromethyl)-4-(4-(trifluoromethoxy)phenyl)-1H-1,2,3-triazol-1-yl)ethyl)-3,5-dimethylisoxazole). With and without the inhibitor, the principal mutagenic event of MNU was GC → AT, but more mutations were observed when the inhibitor was present. Evidence that the mutagenic lesion was m6G was based on mass spectral data collected using O6-methyl-d3-guanine as an internal standard; m6G levels were higher in AA-CW236 treated MEFs by an amount proportional to the higher mutation frequency seen in the same cells. This work establishes gpt delta MEFs as a versatile tool for probing mutagenesis by environmental and therapeutic agents and as a cell culture model in which chemical genetics can be used to determine the impact of DNA repair on biological responses to DNA damaging agents.

The relationship between consumption of nitrite or nitrate and risk of non-Hodgkin lymphoma

Epidemiologic studies of the relationship between nitrite or nitrate consumption and risk of non-Hodgkin lymphoma (NHL) remain controversial. The current meta-analysis aimed to reexamine the evidence and quantitatively evaluate that relationship. Manuscripts were retrieved from the Web of Science, Chinese National Knowledge Infrastructure and PubMed databases up to May 2019. From the studies included in the review, results were combined and presented as odds ratios (OR). To conduct a dose-response (DR) analysis, studies presenting risk estimates over a series of categories of exposure were selected. Our data indicate that the consumption of nitrite was linked to a significantly increased hazard of NHL (OR: 1.37; 95% CI: 1.14–1.65), rather than nitrate (OR: 1.02; 95% CI: 0.94–1.10). According to Egger’s and Begg’s tests (P > 0.05), there was no evidence of significant publication bias. Moreover, our DR analysis indicated that the risk of NHL grew by 26% for each additional microgram of nitrite consumed in the diet per day (OR: 1.26; 95% CI: 1.09–1.42). Through subset analysis of the nitrite studies, data from the high-quality studies indicated that consumption was positively associated with carcinogenicity, leading to NHL (OR: 1.44; 95% CI: 1.17–1.77) and positively correlated with the development of diffuse large B-cell lymphoma (OR: 1.55; 95% CI: 1.07–2.26), but not other NHL subtypes. In addition, the data suggested that females (OR: 1.50; 95% CI: 1.15–1.95) and high levels of nitrite intake (OR: 1.64; 95% CI: 1.28–2.09) had a higher risk of NHL. Our meta-analysis supports the hypothesis that nitrite intake, but not that of nitrate, raises the risk of developing NHL. In the future, better designed prospective research studies should be conducted to confirm our findings, clarify potential biological mechanisms and instruct clinicians about NHL prophylaxis.

Plant-Based Biostimulants Influence the Agronomical, Physiological, and Qualitative Responses of Baby Rocket Leaves under Diverse Nitrogen Conditions

Nitrogen is the primary technical means responsible for food production increase, but on the other hand, wise management is needed because its excessive use can have a negative impact on the environment and on green leafy vegetable quality, such as that rocket. Rocket has the characteristics of accumulating nitrate in leaves with possible impacts on human health. In order to overcome this issue, researchers are focusing their attention on the use of alternative means, such as plant biostimulant application. The scope of this study was to assess the effect of legume-derived protein hydrolysate(LDPH) and tropical plant extract(TPE), combined with various doses of nitrogen (0 kg ha⁻¹ non-fertilized; N0); 60 kg ha⁻¹ (sub-optimal; N1); 80 kg ha⁻¹ (optimal; N2); and 100 kg ha⁻¹ (supra-optimal; N3)), in order to reduce nitrogen use, boost yield, and enhance the chemical and nutritional value of leaves without significantly accumulating nitrate. Both vegetal-based plant biostimulants enhanced plant growth, boosted the marketable yield (especially at N0 and N1 levels, by 38.2% and 28.2%, respectively, compared to the non-treated control), and increased the SPAD (Soil Plant Analysis Development) index and leaf pigments content, such as chlorophyll and carotenoids, especially in treated-LDPH rocket. The plant-based biostimulants also produced a major amplification in lipophilic antioxidant activity (+ 48%) and total ascorbic acid content (average + 95.6%), especially at low nitrogen fertilization levels, and maintained nitrate content under the legal European Comission limits.

Quality of Sliced Cured Pork Loin with Spinach: Effect of Incubation Period with Starter Culture

An increasing concern about the usage of chemical additives in meat products has resulted in the use of natural ingredients instead of chemical additives in meat products. Therefore, this study aimed to investigate the effect of incubation period on the physicochemical characteristics of meat products cured with spinach and starter culture containing Staphylococcus carnosus. The pH, color, TBARS lipid oxidation, volatile basic nitrogen, residual nitrite content, and microbial number in cured pork loin were determined by incubating it with spinach and starter culture for the following durations: 3, 6, 9, 12, 24, and 48 h. The pH and TBARS values of cured pork loin incubated with spinach and starter culture decreased in a time-dependent manner. An increase in the incubation time from 3 to 48 h resulted in a significant increase in the redness and volatile basic nitrogen content. The residual nitrite content was observed to be maximum in samples from the I48 group followed by the control (+), preconverted nitrite group, and I24 groups. Thus, we found that incubation with spinach and starter culture for 24 h yields a good-quality cooked sliced cured pork loin.

The Effects of Beetroot Juice on Blood Pressure, Microvascular Function and Large-Vessel Endothelial Function: A Randomized, Double-Blind, Placebo-Controlled Pilot Study in Healthy Older Adults

Dietary nitrate (NO₃⁻) has been reported to improve endothelial function (EF) and blood pressure (BP). However, most studies only assess large-vessel EF with little research on the microvasculature. Thus, the aim of the present pilot study is to examine NO₃⁻ supplementation on microvascular and large-vessel EF and BP. Twenty older adults (63 ± 6 years) were randomized to a beetroot juice (BRJ) or placebo (PLA) group for 28 (±7) days and attended three laboratory visitations. Across visitations, blood pressure, microvascular function and large-vessel EF were assessed by laser Doppler imaging (LDI) with iontophoresis of vasoactive substances and flow-mediated dilatation (FMD), respectively. Plasma NO₃⁻concentrations, BP and the presence of NO₃⁻ reducing bacteria were also assessed. Plasma NO₃⁻ increased following two weeks of BRJ supplementation (p = 0.04) along with a concomitant decrease in systolic and diastolic BP of approximately −6 mmHg and −4 mmHg, respectively (p = 0.04; p = 0.01, respectively). BP remained unchanged in the PLA group. There were no significant differences in endothelium-dependent or endothelium-independent microvascular responses between groups. FMD increased by 1.5% following two weeks of BRJ (p = 0.04), with only a minimal (0.1%) change for the PLA group. In conclusion, this pilot study demonstrated that medium-term BRJ ingestion potentially improves SBP, DBP and large-vessel EF in healthy older adults. The improvements observed in the present study are likely to be greater in populations presenting with endothelial dysfunction. Thus, further prospective studies are warranted in individuals at greater risk for cardiovascular disease.

Uncured-Labeled Meat Products Produced Using Plant-Derived Nitrates and Nitrites: Chemistry, Safety, and Regulatory Considerations

Consumers often malign conventional curing agents while concomitantly accepting the natural forms of the same constituents in numerous food products. This paradox ostensibly exceeds all other food-related controversies to date and likely contributes to the rapid expansion of meat products that utilize natural nitrate derivatives. While there is high demand for these products, a fundamental lack of understanding regarding the safety and chemical implications of curing agents, whether derived from synthetic or natural sources, continues to persist. This manuscript elucidates the variations among curing preparations with particular emphasis pertaining to the associated safety, chemical, and regulatory ramifications encompassing these product categories.

Long-term consumption of fruits and vegetables and risk of chronic obstructive pulmonary disease: a prospective cohort study of women

Background

Fruits and vegetables, due to high antioxidant capacity, may protect the lung from oxidative damage caused by tobacco smoke and potentially prevent chronic obstructive pulmonary disease (COPD). Only one study based on baseline diet has examined fruit and vegetable consumption in relation to risk of COPD, and no previous studies have examined long-term diet.

Methods

We investigated whether long-term fruit and vegetable consumption was associated with COPD incidence among 34 739 women (age 48-83 years) in the population-based prospective Swedish Mammography Cohort. Fruit and vegetable consumption was assessed twice (1987, 1997) with a self-administered questionnaire. Cases of COPD were identified by linkage to the Swedish health register. Cox proportional hazard regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs).

Results

During follow-up from 2002 to 2014, 1512 women were diagnosed with COPD. Long-term fruit was associated with lower risk of COPD; women in the highest vs lowest quintile of consumption (≥2.5 vs <0.8 servings/day) had a 37% lower risk of COPD (95% CI: 25-48%; P-trend < 0.0001). No association was observed with long-term vegetable intake. Current and ex-smokers with low long-term consumption of fruits (<1 serving/day) in comparison to never smokers with high consumption (≥3 servings/day) had a 38-fold (HR: 38.1; 95% CI: 20.2-71.7) and 13-fold (HR: 12.5, 95% CI: 6.5-24.1) higher risk of COPD, respectively. However, no significant interaction between smoking status and fruit intake in relation to COPD incidence was observed (P-interaction = 0.95).

Conclusions

In this prospective cohort of middle-age and older women, long-term consumption of fruits but not vegetables was inversely associated with COPD incidence.

Performance of surfactant-modified *BEA-type zeolite nanosponges for the removal of nitrate in contaminated water: Effect of the external surface

Hierarchical *BEA-type nanosponges zeolite with a high external surface area (116 m².g^-1) and small crystal size, synthesized in the presence of a dual-porogenic organic compound, were modified with a cationic surfactant (HDTMA⁺Br^-: hexadecyltrimethyl ammonium bromide) in order to create a new anion exchanger system: the surfactant-modified zeolite nanosponges (SMZ_NS). For comparison, two other surfactant-modified *BEA-type zeolite materials, SMZ_MC and SMZ_NC, were obtained by modifying the synthesized conventional micron-size microcrytals and nanocrystals *BEA-type zeolite with HDTMA⁺Br^-, respectively. Textural and structural properties were determined for the three prepared materials using N₂ adsorption/desorption analysis, XRD, SEM, and TEM. Nitrate adsorption isotherms were drawn in a large concentration range [0.8-24.2 mmol.L^-1] and fitted with Langmuir isotherm model. The maximum nitrate removal capacity (1338 mmol.Kg^-1/83 mg.g^-1) was obtained for SMZ_NS material. This value is the highest ever observed for nitrate removal using surfactant-modified zeolite. The nitrate removal kinetics were fitted with the pseudo second-order model for both materials SMZ_NS and SMZ_NC.

Nitrate Accumulation and Expression Patterns of Genes Involved in Nitrate Transport and Assimilation in Spinach

Excessive accumulation of nitrate in spinach is not only harmful to human beings, but also limits the efficiency of nitrogen usage. However, the underlying mechanism of nitrate accumulation in plants remains unclear. This study analyzed the physiological and molecular characteristics of nitrate uptake and assimilation in the spinach varieties with high or low nitrate accumulation. Our results showed that the variety of spinach with a high nitrate content (So18) had higher nitrate uptake compared to the variety with a low nitrate content (So10). However, the nitrate reductase activities of both varieties were similar, which suggests that the differential capacity to uptake and transport nitrate may account for the differences in nitrate accumulation. The quantitative PCR analysis showed that there was a higher level of expression of spinach nitrate transporter (SoNRT) genes in So18 compared to those in So10. Based on the function of Arabidopsis homologs AtNRTs, the role of spinach SoNRTs in nitrate accumulation is discussed. It is concluded that further work focusing on the expression of SoNRTs (especially for SoNRT1.4, SoNRT1.5 and SoNRT1.3) may help us to elucidate the molecular mechanism of nitrate accumulation in spinach.

Potential health impacts from different vegetable nitrate intake scenarios and providing strategies to manage the risks for Iranian population

Health risk from nitrate was predicted for different scenarios of vegetable consumption and nitrate contents in Iran. Finally, certain management scenarios were presented for nitrate risk mitigation under worst-case scenario considering each vegetable contribution in nitrate intake. Two fruit (bell pepper and tomato) and two leafy vegetables (lettuce and mint) were sampled in a combined randomized method from fields, greenhouses, and markets of Isfahan province, Iran during October to December 2015. To assess the potential health impacts of nitrate from the vegetable ingestion, the present status and three different scenarios of increasing vegetable consumption and/or increasing plant nitrate concentrations were considered. Two management scenarios for reducing the total nitrate intake below the allowable values were predicted. By increasing vegetable consumption under scenario 1 and nitrate concentration under scenario 3, the total hazard quotient (THQs) was increased, although the highest increase (12-fold) in the THQs was provided by lettuce. Health risk from nitrate for sensitive groups was effectively reduced by a 70% decrease in lettuce nitrate concentration. In the second management scenario, decreasing upper nitrate concentrations in the other sources (except lettuce) by 30% declined nitrate intake in children (< 6 years old) and boys (7-14 years old) below acceptable daily intake (ADI). By taking into account the increases in the amounts of consumption and nitrate in vegetables at different scenarios, it was revealed that the critical factor for a high dietary exposure to nitrate is not the absolute amount of vegetables consumed but the type of vegetable (lettuce) and the concentration of nitrate related to the conditions of production. Therefore, to manage any risks to human health from dietary nitrate exposure resulting from vegetable consumption, focus on lettuce instead of taking other vegetables equally into account is needed.

Benefit-risk analysis for foods (BRAFO): Evaluation of exposure to dietary nitrates

Dietary nitrate has been associated with health benefits as well as potential risks, thus presenting a paradox for consumers and health professionals. To address the issue, we applied the Benefit-Risk Analysis for Foods (BRAFO) framework to evaluate dietary exposure to nitrate by considering how the risks and benefits might vary under the reference scenario of the acceptable daily intake (ADI) set forth by JECFA (3.7 mg/kg-day), or under an alternative scenario of a higher ADI (independently developed herein). Results demonstrated that risk, as conservatively characterized by various toxicological benchmarks, was present at levels ranging from the current ADI value of 3.7 mg/kg-day (lowest end of the range) to >15 mg/kg-day. When these ADI values, both established by regulatory bodies as well as independently herein were compared to intakes associated with benefits (decreased blood pressure observed following repeated exposure to nitrates ∼4-18 mg/kg-day), along with considerations of current dietary exposures associated with healthy diets, the alternative scenario allowed for benefits without incurring additional risk. For consumers aged 12 weeks and older, ADI values ∼12-17 mg/kg-day-based on more reliable data than used to derive the current ADI-allow benefits to be realized while still protecting public health. The assessment serves as a case study in how benefits can be considered in a risk assessment paradigm for foods, thus providing useful information to decision makers.

Impact of nitrogen source and supply level on growth, yield and nutritional value of two contrasting ecotypes of Cichorium spinosum L. grown hydroponically

BACKGROUND

In the present study, two contrasting stamnagathi (Cichorium spinosum L.) ecotypes originating either from a mountainous or from a seaside habitat were grown hydroponically and supplied with a nutrient solution differing in the total-N level (4 or 16 mmol L^-1 ) and the N source (NH₄⁺ -N/total-N: 0.05, 0.25 or 0.50). The aim was to search for genotypic differences in nitrogen nutrition.

RESULTS

At commercial maturity, the dry weight of mountainous plants was higher than that of seaside plants. The shoot mineral concentrations were higher in seaside plants than in mountainous plants in both harvests. The leaf nitrate concentration was influenced by the levels of both total-N and NH₄⁺ -N/total-N at both harvests, whereas plants with a seaside origin exhibited higher nitrate concentrations than those originating from a mountainous site in all total-N and NH₄⁺ -N/total-N treatments.

CONCLUSION

The two stamnagathi ecotypes differed considerably in their responses to nitrogen nutrition and tissue nitrate content. The mountainous ecotype was superior in terms of growth, tissue nitrate concentration and antioxidant capacity, whereas the seaside ecotype accumulated more nutrient microcations in leaves. A low total-N concentration (up to 4 mmol L^-1 ) combined with a high NH₄⁺ -N/total-N ratio (up to 0.05) could minimize tissue NO₃^- concentrations without compromising yield. © 2017 Society of Chemical Industry.

Effect of natural pre-converted nitrite sources on color development in raw and cooked pork sausage

Objective

The effect of pre-converted nitrites from natural sources (spinach, lettuce, celery, and red beet) on color development in raw and cooked pork sausage was investigated in this study.

Methods

The pork sausage was manufactured with six treatments: NC (negative control, nitrite free), PC (positive control, 150 ppm sodium nitrite), FS (3.0% fermented spinach extracts), FL (3.0% fermented lettuce extracts), FC (3.0% fermented celery extracts), and FR (3.0% fermented red beet extracts).

Results

The pH value of the pre-converted nitrites groups was lower than those treated with 150 ppm sodium nitrite (p<0.05). The color values of raw and cooked pork sausage added with pre-converted nitrite showed slightly lower and/or similar lightness, lower redness, and higher yellowness values than PC. Color development (redness values) of cooked samples added with FS was higher than those of the NC and other treatments (FL, FC, and FR). Additionally, treatments with FS and FL were most effective for reducing thiobarbituric acid reactive substances and volatile basic nitrogen than the NC.

Conclusion

Effects of natural nitrites from fermented vegetables on shelf stability of raw and cooked pork sausages were investigated. Fermented spinach extract was much more useful for maintaining the color development, but also inhibiting lipid and protein oxidation of cooked pork sausage. Therefore, pre-converted nitrite from spinach as a natural nitrite could be used as another natural nitrite source for making processed meat products.

Exposure estimates of nitrite and nitrate from consumption of cured meat products by the U.S. population

The dietary exposures of nitrite and nitrate from consumption of cured meat products were estimated for the U.S. population aged 2 years and older, and children aged 2 to 5 years, using both 2-day food consumption data from the publicly available combined 2009-2012 National Health and Nutrition Examination Survey (NHANES) and 10-14-day food consumption data from the 2009 and 2012 NPD Group, Inc. National Eating Trends-Nutrient Intake database (NPD NET-NID), and residual nitrite and nitrate levels in cured meat products available from the recent American Meat Institute Foundation/National Pork Board (AMIF/NPB) national market survey of the nitrite and nitrate levels in cured meat products in the U.S.A. The dietary exposure for consumers of cured meat products (eaters-only) was estimated at the mean and 90th percentile for three exposure scenarios: low exposure, average exposure, and high exposure, to account for the range in the amount of nitrite and nitrate in a given cured meat product category. In addition, a cumulative exposure that takes into account all cured meat product categories containing nitrite and nitrate was determined, and the relative percent contribution of each cured meat product category to the cumulative exposure was estimated. Cured, cooked sausages and whole-muscle brine-cured products were the two major contributing categories to dietary exposure of nitrite and nitrate for both U.S. population aged 2 years and older and children aged 2-5 years.

Improvement of yield and quality of two Spinacia oleracea L. varieties by using different fertilizing approaches

The effects of different fertilizers [the control with no fertilizer (C), inorganic fertilization (I), combined inorganic and organic fertilizer (IOHumax1) and (IOHumax2)] on yield and nutrients contents of two spinach varieties ("Balady and Virofly") were investigated. Significant effects of variety were observed on vegetative growth and nutrients contents. While Virofly had significantly higher leaf area (236.96 cm²), stem diameter (7.43 mm) and fresh weight of vegetative and radical parts (15.05 and 0.96 g, respectively), Balady had significantly higher chlorophyll and carotene contents (0.0023 and 0.0018 g/g fw, respectively). No significant impacts of variety on vitamin C, nitrite, nitrate and oxalates contents were observed. IOHumax2 treatment (4 g/l of Humax + 100 mg/l of NH₄NO₃ per plant fertigation^-1) enhanced stem diameter and root growth and significantly improved the yield by produced plants with higher stem length, leaf number and surface area. This treatment improved the quality of plant by increasing vitamin C content and reducing nitrite and oxalates contents. No significant effects of different fertilizers were observed on NO₃^- content. A fairly balanced yield/NO₃^- and oxalates content can be achieved with combined inorganic and organic fertilizer (IOHumax1) and (IOHumax2).

The role of inorganic nitrate and nitrite in CVD

CVD is the leading cause of death worldwide, a consequence of mostly poor lifestyle and dietary behaviours. Although whole fruit and vegetable consumption has been consistently shown to reduce CVD risk, the exact protective constituents of these foods are yet to be clearly identified. A recent and biologically plausible hypothesis supporting the cardioprotective effects of vegetables has been linked to their inorganic nitrate content. Approximately 60–80 % inorganic nitrate exposure in the human diet is contributed by vegetable consumption. Although inorganic nitrate is a relatively stable molecule, under specific conditions it can be metabolised in the body to produce NO via the newly discovered nitrate–nitrite–NO pathway. NO is a major signalling molecule in the human body, and has a key role in maintaining vascular tone, smooth muscle cell proliferation, platelet activity and inflammation. Currently, there is accumulating evidence demonstrating that inorganic nitrate can lead to lower blood pressure and improved vascular compliance in humans. The aim of this review is to present an informative, balanced and critical review of the current evidence investigating the role of inorganic nitrate and nitrite in the development, prevention and/or treatment of CVD. Although there is evidence supporting short-term inorganic nitrate intakes for reduced blood pressure, there is a severe lack of research examining the role of long-term nitrate intakes in the treatment and/or prevention of hard CVD outcomes, such as myocardial infarction and cardiovascular mortality. Epidemiological evidence is needed in this field to justify continued research efforts.

Re-evaluation of potassium nitrite (E 249) and sodium nitrite (E 250) as food additives

The Panel on Food Additives and Nutrient Sources added to Food (ANS) provided a scientific opinion re-evaluating the safety of potassium nitrite (E 249) and sodium nitrite (E 250) when used as food additives. The ADIs established by the SCF (1997) and by JECFA (2002) for nitrite were 0-0.06 and 0-0.07 mg/kg bw per day, respectively. The available information did not indicate in vivo genotoxic potential for sodium and potassium nitrite. Overall, an ADI for nitrite per se could be derived from the available repeated dose toxicity studies in animals, also considering the negative carcinogenicity results. The Panel concluded that an increased methaemoglobin level, observed in human and animals, was a relevant effect for the derivation of the ADI. The Panel, using a BMD approach, derived an ADI of 0.07 mg nitrite ion/kg bw per day. The exposure to nitrite resulting from its use as food additive did not exceed this ADI for the general population, except for a slight exceedance in children at the highest percentile. The Panel assessed the endogenous formation of nitrosamines from nitrites based on the theoretical calculation of the NDMA produced upon ingestion of nitrites at the ADI and estimated a MoE > 10,000. The Panel estimated the MoE to exogenous nitrosamines in meat products to be < 10,000 in all age groups at high level exposure. Based on the results of a systematic review, it was not possible to clearly discern nitrosamines produced from the nitrite added at the authorised levels, from those found in the food matrix without addition of external nitrite. In epidemiological studies there was some evidence to link (i) dietary nitrite and gastric cancers and (ii) the combination of nitrite plus nitrate from processed meat and colorectal cancers. There was evidence to link preformed NDMA and colorectal cancers.

Dietary nitrate and blood pressure: evolution of a new nutrient?

Dietary nitrate is mainly obtained from vegetables, especially green leafy vegetables and beetroot. As a result of early research, dietary nitrate is currently viewed as a contaminant linked to increased risks of stomach cancer and methaemoglobinaemia. Consequently, nitrate levels are restricted in certain vegetables and in water supplies to ensure exposure levels remain below an acceptable daily intake of 3·7 mg/kg per d. The average nitrate intake in the UK is approximately 70 mg/d, although some population groups, such as vegetarians, may consume three times that amount. However, recent studies in the last decade suggest that dietary nitrate can significantly reduce systolic blood pressure via the nitrate-nitrite-NO pathway. A small, downward shift in systolic blood pressure across the population could significantly reduce the incidence of hypertension and mortality from CVD such as stroke. Interestingly, vegetarians tend to have lower levels of blood pressure than omnivores and epidemiological studies suggest that vegetarians have lower risks of CVD. Recent evidence is mainly focused on the acute effects of dietary nitrate supplementation and there is a lack of data looking at the chronic effects of high nitrate consumption in humans. Nevertheless, due to potential health benefits, some authors are recommending that nitrate should be considered as a nutrient necessary for health, rather than as a contaminant which needs to be restricted. This review will discuss the emerging role of dietary nitrate in the control of blood pressure and whether there is sufficient evidence to state that nitrate is a 'new' nutrient.

Effects of Pre-Converted Nitrite from Red Beet and Ascorbic Acid on Quality Characteristics in Meat Emulsions

We investigated the effects of fermented red beet extract and ascorbic acid on color development in meat emulsions. The pH of meat emulsions containing red beet extract decreased with an increase in the amount of extract added. The redness of the treated meat emulsions was higher than that of the control with no added nitrite or fermented red beet extract (p<0.05), though the redness of the meat emulsions treated with fermented red beet extract only was lower than in that treated with both fermented red beet extract and ascorbic acid (p<0.05). The highest VBN, TBARS, and total viable count values were observed in the control, and these values in the meat emulsions treated with fermented red beet extract were higher than in that treated with both fermented red beet extract and ascorbic acid (p<0.05). E. coli and coliform bacteria were not found in any of the meat emulsions tested. Treatment T2, containing nitrite and ascorbic acid, had the highest overall acceptability score (p<0.05); however, there was no significant difference between the T2 treatment and the T6 treatment, which contained 10% pre-converted nitrite from red beet extract and 0.05% ascorbic acid (p>0.05). The residual nitrite content of the meat emulsions treated with ascorbic acid was lower than in those treated without ascorbic acid (p<0.05). Thus, the combination of fermented red beet extract and ascorbic acid could be a viable alternative to synthetic nitrite for the stability of color development in meat emulsions.

NITRATE IN LEAFY GREEN VEGETABLES AND ESTIMATED INTAKE

BACKGROUND

Vegetarian diets are rich in vegetables. Green leafy vegetables are foods that contain considerable amounts of nitrate, which can have both positive and negative effects on the human body. Their potential carcinogenicity and toxicity have been proven, particularly after the reduction of nitrate to nitrite itself or just serving as a reactant with amines and/or amides in the formation of N-nitroso compounds -N-nitrosamines and other nitrogen compounds which may have high levels of nitrate. The aim of this study was to determine whether there is a significant difference, considering the location and seasonal sampling period, in the level of nitrate in certain types of green vegetables, all in order to be able to assess their intake, and possible impact on human health, especially knowing that exposure to nitrate can be potentially higher for vegetarian population group.

MATERIALS AND METHODS

For this purpose, the sampling of 200 different leafy green vegetables was conducted, all of which could be found in free sale in the Republic of Croatia. The sampling was conducted during two seasonal periods - the spring and autumn period. In the springtime, lettuce (sem), spinach (pinacho), kale (kale), chard (mangel) and cabbage (brassica) were sampled, and in autumn lettuce, spinach, kale, chard and arugula. Samples were analyzed using high performance liquid chromatography (HPLC) with UV detection.

RESULTS

The results from the spring sampling phase were in the range of 603 mg/kg for cabbage - 972 mg/kg for chard, and for autumn phase of 1.024 mg/kg for chard to 4.354 mg/kg for the arugula. The results showed that there were significant differences (p <0.05) for most of the samples analyzed, considering the sampling locations and time period.

CONCLUSION

The results indicate that the analyzed vegetables contain significant amounts of nitrate in their composition, which represents relatively significant, but still acceptable intake into the human body.

Effect of Fermented Spinach as Sources of Pre-Converted Nitrite on Color Development of Cured Pork Loin

The effect of fermented spinach extracts on color development in cured meats was investigated in this study. The pH values of raw cured meats without addition of fermented spinach extract or nitrite (negative control) were higher (p<0.05) than those added with fermented spinach extract. The pH values of raw and cooked cured meats in treatment groups were decreased with increasing addition levels of fermented spinach extract. The lightness and yellowness values of raw cured meats formulated with fermented spinach extract were higher (p<0.05) than those of the control groups (both positive and negative controls). The redness values of cooked cured meats were increased with increasing fermented spinach extract levels, whereas the yellowness values of cooked cured meats were decreased with increasing levels of fermented spinach extract. The lowest volatile basic nitrogen (VBN) and thiobarbituric acid reactive substances (TBARS) values were observed in the positive control group with addition of nitrite. TBARS values of cured meats added with fermented spinach extract were decreased with increasing levels of fermented spinach extract and VBN values of curing meat with 30% fermented spinach extract was lower than the other treatments. Total viable bacterial counts in cured meats added with fermented spinach extract ranged from 0.34-1.01 Log CFU/g. E. coli and coliform bacteria were not observed in any of the cured meats treated with fermented spinach extracts or nitrite. Residual nitrite contents in treatment groups were increased with increasing levels of fermented spinach extract added. These results demonstrated that fermented spinach could be added to meat products to improve own curing characteristics.

Analysis of Nitrite and Nitrate in Foods: Overview of Chemical, Regulatory and Analytical Aspects

In this chapter, several factors that should be considered for selecting and developing suitable analytical methods for determining nitrite/nitrate are presented. Nitrite and nitrate occurrence and suitability are a controversial issue. Nitrite is an approved additive considered a foremost curing ingredient for the preservation of meat products. Nitrate is a natural constituent of the human diet that, however, raises fears for its suggested potential harmfulness related to carcinogenesis and environmental contamination. Chemical, regulatory, and analytical aspects are discussed in the light of the need to obtain reliable data of nitrite and nitrate for law enforcement purposes, exposure estimates, and investigation of their physiological role in the human body. In addition, current metrological aspects to ensure the "fitness for purpose" of the selected method are suggested and discussed.

How are nitrosothiols formed de novo in vivo?

The biological mechanisms of de novo formation of cellular nitrosothiols (as opposed to transnitrosation) are reviewed. The approach is to introduce chemical foundations for each mechanism, followed by evidence in biological systems. The general categories include mechanisms involving nitrous acid, NO autoxidation and oxidant stress, redox active and inactive metal ions, and sulfide/persulfide. Important conclusions/speculations are that de novo cellular thiol nitrosation (1) is an oxidative process, and so should be considered within the family of other thiol oxidative modifications, (2) may not involve a single dominant process but depends on the specific conditions, (3) does not involve O₂ under at least some conditions, and (4) may serve to provide a "substrate pool" of protein cysteine nitrosothiol which could, through subsequent enzymatic transnitrosation/denitrosation, be "rearranged" to accomplish the specificity and regulatory control required for effective post-translational signaling.