Assessment of the combined nitrate and nitrite exposure from food and drinking water: application of uncertainty around the nitrate to nitrite conversion factor

The association of dietary nitrates/nitrites intake and the gut microbial metabolite trimethylamine N-oxide and kynurenine in adults: a population-based study

Background

Dietary nitrate and nitrite may affect the gut microbiota and its metabolites, such as trimethylamine N-oxide (TMAO) and kynurenine (KYN). However, this association and the exact mechanism are still unclear. Therefore, this study aimed to assess the association between dietary consumption of nitrite and nitrate on TMAO and KYN levels in adults.

Methods

This cross-sectional study was employed on a subsample baseline phase of the Tehran University of Medical Sciences (TUMS) Employee's Cohort Study (TEC). A total of 250 adults aged 18 years or older were included in the current analysis. Data on the dietary intakes were collected using a validated dish-based food frequency questionnaire (FFQ), and dietary intakes of nitrite and nitrate were estimated using the FFQ with 144 items. Serum profiles and TMAO and KYN were measured using a standard protocol.

Results

The findings of this study demonstrate a significant association between the intake of animal sources of nitrate and nitrite and the likelihood of having elevated levels of TMAO and KYN. Specifically, after adjustment, individuals with the highest intake adherence to nitrates from animal sources exhibited increased odds of having the highest level of TMAO (≥51.02 pg/ml) (OR = 1.51, 95% CI = 0.59-3.88, P = 0.03) and KYN (≥417.41 pg/ml) (OR = 1.75, 95% CI = 0.73-4.17, P = 0.02). Additionally, subjects with the highest animal intake from nitrite sources have 1.73 and 1.45 times higher odds of having the highest levels of TMAO and KYN. These results emphasize the potential implications of animal-derived nitrate and nitrite consumption on the levels of TMAO and KYN.

Conclusion

The present evidence indicates that a high level of nitrate and nitrite intake from animal sources can increase the odds of high levels of TMAO and KYN. Further studies suggest that we should better evaluate and understand this association.

Determination of nitrate and nitrite levels in enteral nutrition formula marketed in Turkey: A risk assessment study

In this study, the nitrite and nitrate levels of 37 enteral nutrition formulas of three different international brands marketed in Turkey were evaluated using high-performance liquid chromatography with diode-array detection (HPLC-DAD). Also, risk assessment of non-carcinogenic was calculated by models including hazard quotient (HQ) and hazard index (HI) in the deterministic model. Enteral nutrition formula consumption amounts obtained from individuals between the ages of 6-36 volunteers voluntarily participated in the study, and health risk assessments were calculated. The range of concentration of nitrate levels in enteral formulas of brands (B1, B2, and B3) was determined as 11.08 ± 2.88 (2.90-15.79), 11.64 ± 3.39 (2.92-22.93), and 10.66 ± 3.46 (4.92-15.37) mg/kg, respectively. The range of concentration of nitrite levels in enteral formulas of brands (B1, B2, and B3) was determined as 4.18 ± 1.10 (1.86-5.82), 3.70 ± 1.25 (1.29-5.26), and 3.38 ± 1.67 (2.00-5.29) mg/kg, respectively. The mean nitrate and nitrite levels of exposure from consumption of enteral nutrition formulas were determined as 0.14 and 0.11, 0.06 and 0.07 mg/kg bw/day for females and males, respectively. Nitrate and nitrite exposure levels calculated in the study did not exceed the ADI threshold values given by JECFA. The average HQ value calculated for the exposure of nitrate to male and female individuals was less than 1. Still, the P95 values calculated for nitrate were greater than 1.00 except for female and male individuals (24-36 ages). The HI value was found to be greater than 1.00 in all age groups of both genders. The presence of nitrites and nitrates in enteral nutrition formulas may lead to health problems in sensitive groups.

Removal of Nitrate Nitrogen in Groundwater by Attapulgite Loaded with Nano-Zero-Valent Iron

Nano-zero-valent iron (nZVI) can be used to remove nitrate nitrogen (NO3-N) from groundwater. However, it has low reduction efficiency owing to its oxidation and aggregation characteristics. Thus, nZVI-loaded material is used to alleviate these drawbacks. In this study, nZVI-coated attapulgite (ATP) was prepared for the removal of NO3-N from groundwater. ATP-nZVI was prepared using the chemical liquid deposition-coreduction method. The prepared materials were characterized by SEM, XRD, and XPS analyses, which confirmed that the aluminum silicate particles in the ATP structure are effective carriers of nZVI and effectively inhibit self-consumption caused by the oxidation and aggregation of nZVI. The batch experiments examined experimental samples containing 30 mg/L nitrate and analyzed the effects of various parameters, including the material, mass ratio, initial pH, initial temperature, and coexisting anions on the NO3-N removal efficiency. The results showed that the optimal removal rate of the composite was 78.61%, which is higher than that using the same amount of ATP, iron powder, and nZVI. When the mass ratio of ATP to nZVI was 1 : 1, the NO3-N removal efficiency was the highest. When the pH value increased from 3 to 9, the NO3-N removal rate decreased, while an increase in the reaction temperature promoted NO3-N removal. The order of the inhibitory effect of coexisting anions on NO3-N removal by various nanoions was PO43–>CO32–>SO42–>Cl–. The adsorption kinetic model fitting results indicated that the chemisorption of electron exchange between ATP and nZVI in NO3-N removal was the main rate-limiting step in the reaction. This study demonstrates the potential of the prepared ATP-nZVI composite for NO3-N removal from groundwater.

Nitrites in Cured Meats, Health Risk Issues, Alternatives to Nitrites: A Review

Nitrite is one of the most widely used curing ingredients in meat industries. Nitrites have numerous useful applications in cured meats and a vital component in giving cured meats their unique characteristics, such as their pink color and savory flavor. Nitrites are used to suppress the oxidation of lipid and protein in meat products and to limit the growth of pathogenic microorganisms such as Clostridium botulinum. Synthetic nitrite is frequently utilized for curing due to its low expenses and easier applications to meat. However, it is linked to the production of nitrosamines, which has raised several health concerns among consumers regarding its usage in meat products. Consumer desire for healthier meat products prepared with natural nitrite sources has increased due to a rising awareness regarding the application of synthetic nitrites. However, it is important to understand the various activities of nitrite in meat curing for developing novel substitutes of nitrites. This review emphasizes on the effects of nitrite usage in meat and highlights the role of nitrite in the production of carcinogenic nitrosamines as well as possible nitrite substitutes from natural resources explored also.

Risk Assessment of Nitrite and Nitrate Intake from Processed Meat Products: Results from the Hellenic National Nutrition and Health Survey (HNNHS)

Long-term exposure to a high nitrite and nitrate intake through processed meat is of concern, as it has been related to adverse health effects. Individual consumption data from 2152 participants (46.7% males) in the Hellenic National Nutrition and Health Survey (HNNHS) were linked with current Maximum Permitted Levels (MPLs) to calculate exposure to nitrite and nitrate from processed meat products (assessed as nitrite equivalent), evaluate potential risk and identify the major contributors. Processed meat intakes were determined by combining data from 24 h recalls and frequency of consumption reported in Food Propensity Questionnaires (FPQs). Median exposure was estimated to be within safe levels for all population groups. However, 6.6% (n = 143) of the consumers exceeded the Acceptable Daily Intake (ADI) of nitrite (0.07 mg/kg bw/day), of which 20.3% were children aged 0-9 years (N = 29) (15.3% of all children participants in the study, N = 190). In total, pork meat was the major contributor (41.5%), followed by turkey meat (32.7%) and sausages (23.8%), although contribution variations were found among age groups. The outcomes are of public health concern, especially exposure among children, and future research is warranted to evaluate possible associations with health effects, by using more refined occurrence data if available.

Aggregating exposures and toxicity equivalence approach into an integrated probabilistic dietary risk assessment for perchlorate, nitrate, and thiocyanate: Results from the National food monitoring study and National Food Consumption Database

Perchlorate, nitrate, and thiocyanate, namely thyroid disrupting chemicals (TDCs), are found ubiquitously in the environment, leading to broad human exposure and primary uptake through the food web and drinking water. TDCs are all competitive inhibitors of thyroid iodide uptake activity, but limited studies have assessed the cumulative risk of dietary exposure to multiple TDCs. Thus, in this study, we analyzed the individual exposure risk from 310 food samples in 11 categories, and also assessed the cumulative health risks from TDCs for the Taiwanese population using a perchlorate equivalent concentration (PEC) approach. Consequently, this study not only demonstrated the non-carcinogenic health risks from individual exposure but also highlighted that the cumulative exposure to these TDCs may adversely affect human thyroid functioning. Vegetables, livestock, fruits, and dairy products are the most susceptible to PEC exposure. We highlighted nitrate as the main contributor to PEC exposure. Finally, controlling the overall TDC concentrations from vegetables, livestock, fruits, and dairy products is emphasized in this study. This is the first study to conduct a cumulative risk assessment of dietary exposure to TDCs using the PEC approach for the Taiwanese population through probabilistic and sensitivity analyses.

Quantification and health risk assessment of nitrate in southern districts of Tehran, Iran

Nitrate is a common contaminant of drinking water. Due to its adverse health effects, this study aimed to determine nitrate levels in six southern districts of Tehran. A total of 148 samples were taken from tap waters. In 84.46% (n = 125) of the samples, the nitrate concentration was below national and WHO limits (50 mg/L); however, 15.54% (n = 23) were in violation of the criteria. The total mean concentration of nitrate was 36.15 mg/L (±14.74) ranging from 4.52 to 80.83 mg/L. The overall hazard quotient (HQ) for age groups were ordered as Children (1.71) > Infants (1.24) > Teenagers (1.2) > Adults (0.96). In all districts, the HQ values for infants and children groups were greater than 1, indicating potential adverse health risks. In teenagers age group, only the HQ estimations of districts 10 (HQ = 0.93) and 11 (HQ = 0.74) were lower than 1 and in adults age group, the estimated HQ values for districts were lower than 1 with the exception for district 19 (HQ = 1.19). The sensitivity analysis (SA) showed that nitrate content plays a major role in the value of the assessed risk.

The Intake of Phosphorus and Nitrites through Meat Products: A Health Risk Assessment of Children Aged 1 to 9 Years Old in Serbia

This study provides the data on dietary exposure of Serbian children to nitrites and phosphorus from meat products by combining individual consumption data with available analytical data of meat products. A total of 2603 and 1900 commercially available meat products were categorized into seven groups and analysed for nitrite and phosphorous content. The highest mean levels of nitrite content, expressed as NaNO2, were found in finely minced cooked sausages (40.25 ± 20.37 mg/kg), followed by canned meat (34.95 ± 22.12 mg/kg) and coarsely minced cooked sausages (32.85 ± 23.25 mg/kg). The EDI (estimated daily intake) of nitrites from meat products, calculated from a National Food Consumption Survey in 576 children aged 1-9 years, indicated that the Serbian children population exceeded the nitrite ADI (acceptable daily intake) proposed by EFSA (European Food Safety Authority) in 6.4% of children, with a higher proportion in 1-3-year-old participants. The mean phosphorus concentration varied from 2.71 ± 1.05 g/kg to 6.12 ± 1.33 g/kg in liver sausage and pate and smoked meat products, respectively. The EDI of phosphorus from meat products was far below the ADI proposed by EFSA, indicating that the use of phosphorus additives in Serbian meat products is generally in line with legislation.

Dietary nitrate and nitrite and human health: a narrative review by intake source

Nitrate and nitrite are plant nutrients that, although ubiquitous in plant foods, are highly controversial substances in human nutrition because they are also used as additives in processed foods and may be found as contaminants in drinking water. The aim for this narrative review is to provide a thorough insight into the current literature on the relationship between dietary nitrate and nitrite and the health risks and benefits by source of intake. The results highlight beneficial effects of nitrate and nitrite consumption from plant origin on cardiovascular disease and, to date, no positive correlation has been reported with cancer. On the contrary, high intake of these compounds from processed animal-based foods is related to an increased risk of gastro-intestinal cancer. Nitrate in drinking water also raises some concern, because it appears to be related to adverse health effects. The up-to-date debate on the role of nitrate and nitrite in human nutrition seems to be justified and more research is required to verify safe consumption.

Effect on health from consumption of meat and meat products

The aim of this study was to investigate the effects of dietary sodium nitrite and meat on human health. Sodium nitrite in processed meat is known to be one of the main precursors of carcinogens, such as N-nitroso compounds. However, we previously found that processed meat is not the primary source of sodium nitrite; nitrate or the conversion of nitrate in vegetables are contribute to generate more than 70% Sodium nitrite or nitrate containing compounds in body. Although the heavy consumption of meat is likely to cause various diseases, meat intake is not the only cause of colorectal cancer. Our review indicates that sodium nitrite derived from foods and endogenous nitric oxide may exhibit positive effects on human health, such as preventing cardiovascular disease or improving reproductive function. Therefore, further epidemiological studies considering various factors, such as cigarette consumption, alcohol consumption, stress index, salt intake, and genetic factors, are required to reliably elucidate the effects of dietary sodium nitrite and meat on the incidence of diseases, such as colorectal cancer.

Reviewing chemical and biological risks in urban agriculture: A comprehensive framework for a food safety assessment of city region food systems

Attention to urban agriculture (UA) has recently grown among practitioners, scientists, and the public, resulting in several initiatives worldwide. Despite the positive perception of modern UA and locally grown, fresh produce, the potential food safety risks connected to these practices may be underestimated, leading to regulatory gaps. Thus, there is a need for assessment tools to evaluate the food safety risks connected to specific UA initiatives, to assist practitioners in self-evaluation and control, and to provide policy makers and scholars a means to pursue and assess food safety in city regions, avoiding either a lack or an excess of regulation that could ultimately hinder the sector. To address this aim, this paper reviews the most recent and relevant literature on UA food safety assessments. Food safety indicators were identified first. Then, a food safety assessment framework for UA initiatives was developed. The framework uses business surveys and food analyses (if available) as a data source for calculating a food safety index for single UA businesses and the whole UA landscape of a given city region. The proposed framework was designed to allow its integration into the CRFS (City Region Food System) toolkit developed by FAO (Food and Agriculture Organization of the United Nations), RUAF foundation (Resource Centres on Urban Agriculture and Food Security) and Wilfrid Laurier University.

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Connection of several biological and chemical food safety risks to UA techniques.

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Identifiable food safety risk factors for diverse UA practices.

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Framework for the assessment of food safety levels of UA initiatives.

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Development of a risk-based assessment that can be integrated into the FAO CRFS framework.

Improved spectrophotometric method for nitrite determination in processed foods and dietary exposure assessment for Korean children and adolescents

A spectrophotometric method based on diazo-coupling reaction for nitrite analysis was established and validated, including inter-laboratory validation, linearity, accuracy, precision, the limit of detection (LOD) and limit of quantification (LOQ). The time-saving and high-recovery method was established by examining the filtration step, colorimetric process and concentration range of the calibration curve. This method showed good linearity (r² > 0.999) in the range of 0.025-1.0 μg/mL. The three-level recoveries were between 86.7% and 108.6%, with the coefficient of variation (CV) below 5.8%. Mean nitrite concentration ranges in processed foods were ND-33.47 mg/kg. The mean nitrite intake was 0.8% of the Acceptable Daily Intake (ADI, 0.07 mg/kg bw/day) for all children and adolescents and 2.8% for the consumer group. The major contributors for all subjects and consumers were ham, sausage and bacon. These results indicated that the improved method was suitable for analyzing nitrite in processed foods and the nitrite exposure levels were safe.

Nitrite and nitrate content in meat products and estimated nitrite intake by the Estonian children

Public interest in nitrate and nitrite content reduction in meat products has increased; therefore, the aim of the present study was to determine nitrate and nitrite levels in commercial meat products as the main source of added nitrites, and to estimate their dietary intake by children. The intake of nitrite from processed meat products and drinking water by Estonian children was estimated. Daily intake estimations were based on the food consumption data of the National Institute for Health Development. In addition, nitrite/nitrate concentrations of meat and processed meat products were measured using a liquid chromatographic method with UV detection. Mean nitrite intakes among 1087 studied children were 0.015 and 0.016 mg kg^-1 b.w. day^-1, respectively, among children aged 12-35 months and 3-10 years. Acceptable daily intake (ADI) of 0.07 mg nitrite kg^-1 b.w. day^-1 was exceeded in 3.1% of children, being more prevalent in the younger age group. Considering the consumption of processed meat and drinking water, mean nitrite intakes in the younger and the older age groups were, respectively, 21.9% and 22.9% of the ADI. Study results indicated that over a period of 10 years, children's dietary nitrite intake from processed meat products has declined, which is probably caused by changes in food preferences and decreased usage of nitrite in cured meat products by meat industries.