Association of Dietary Nitrate, Nitrite, and N-Nitroso Compounds Intake and Gastrointestinal Cancers: A Systematic Review and Meta-Analysis

The Association between the Substitution of Red Meat with Legumes and the Risk of Primary Liver Cancer in the UK Biobank: A Cohort Study

Primary liver cancer is globally on the rise, partially due to poor diets and sedentary lifestyles. Shifting to more plant-based diets may lower the risk. We aimed to estimate the effect of replacing total red meat, unprocessed red meat and processed red meat with legumes on primary liver cancer in a free-living population. We analyzed data from 126,744 UK Biobank participants who completed ≥ two 24 h diet recalls. Baseline characteristics were collected from the initial assessment visit. Information on liver cancer diagnoses was collected via external linkage to inpatient hospital episodes or central cancer registries. Cox proportional hazards regression models were used to estimate the substitution of 15 g/day of legumes with 15 g/day of total red meat, unprocessed red meat or processed red meat on liver cancer risk, using the leave-one-out food substitution model. During a median follow-up time of 11.1 years, 173 participants developed liver cancer. In the fully adjusted models, no association was observed when substituting 15 g/day of legumes with total red meat (HR: 1.02 (95% CI 0.96-1.08)), unprocessed red meat (HR: 1.00 (95% CI 0.94-1.06)) or processed red meat (HR: 1.09 (95% CI 0.99-1.21)). Overall, little evidence of an association between replacing red meat with legumes and liver cancer was observed. Further research in other study populations with longer follow-up time is warranted.

DNA demethylase TET2-mediated reduction of HADHB expression contributes to cadmium-induced malignant progression of colorectal cancer

Environmental exposure to the cadmium (Cd) has been shown to be a risk factor for colorectal cancer (CRC) progression, but the exact mechanism has not been fully elucidated. In this study, we found that chronic Cd (3 μM) exposure promoted the proliferation, adhesion, migration, and invasion of CRC cells in vitro, as well as lung metastasis in vivo. RNA-seq and TCGA-COAD datasets revealed that decreased hydroxyacyl-CoA dehydrogenase trifunctional multienzyme complex subunit beta (HADHB) expression may be a crucial factor in Cd-induced CRC progression. Further analysis using qRT-PCR and tissue microarrays from CRC patients showed that HADHB expression was significantly reduced in CRC tissues compared to adjacent normal tissues, and low HADHB expression was associated with adverse clinical features and poor overall survival, either directly or through TNM stage. Furthermore, HADHB was found to play an important role in the Cd-induced malignant metastatic phenotype of CRC cells and lung metastasis in mice. Mechanistically, we discovered that chronic Cd exposure resulted in hypermethylation of the HADHB promoter region via inhibition of DNA demethylase tet methylcytosine dioxygenase 2 (TET2), which then led to decreased HADHB expression and activation of the FAK signaling pathway, and ultimately contributed to CRC progression. In conclusion, this study provided a new potential insight and evaluable biomarker for Cd exposure-induced CRC progression and treatment.

Effects of beetroot juice on blood pressure in hypertension according to European Society of Hypertension Guidelines: A systematic review and meta-analysis

AIMS

It has been suggested that nitrate-rich beetroot juice (BRJ) reduces blood pressure (BP) in various populations. We aimed to investigate the effect of BRJ on BP in adults with hypertension according to the European Society of Hypertension Guidelines (clinical BP ≥ 140/≥ 90 mmHg) and whether BRJ can be considered as an adjunct to hypertension drug treatment, by conducting a meta-analysis of randomized controlled trials.

DATA SYNTHESIS

PubMed, SCOPUS, Medline Ovid, Cinahl, Cochrane Library and Web of Science were searched from inception until April 13, 2024 to identify randomized controlled trials of BRJ versus placebo, water, or no intake. Risk of bias was assessed using a standardized appraisal instrument from the Swedish Agency for Health Technology and Assessment of Social Services, which is based on the Cochrane risk-of-bias tool for randomized trials. The pooled BP effect size was calculated using random effects models and meta-regression. Certainty of evidence was assessed using GRADE. Eleven trials (349 patients) were included. BRJ yielded a significant reduction in clinical systolic BP compared with placebo mean difference (MD) -5.31 mmHg (95% CI -7.46, -3.16; I2 = 64%, GRADE ⊕⊕OO). There was no significant effect on clinical diastolic BP or 24-h BP outcomes, and the heterogeneity was moderate to high.

CONCLUSIONS

Daily ingestion of 200-800 mg of nitrate from BRJ may reduce clinical systolic BP in hypertensive individuals with no sign of development of tolerance. Certainty of evidence is low, and results should be interpreted with caution.

Unveiling the gastric microbiota: implications for gastric carcinogenesis, immune responses, and clinical prospects

High-throughput sequencing has ushered in a paradigm shift in gastric microbiota, breaking the stereotype that the stomach is hostile to microorganisms beyond H. pylori. Recent attention directed toward the composition and functionality of this 'community' has shed light on its potential relevance in cancer. The microbial composition in the stomach of health displays host specificity which changes throughout a person's lifespan and is subject to both external and internal factors. Distinctive alterations in gastric microbiome signature are discernible at different stages of gastric precancerous lesions and malignancy. The robust microbes that dominate in gastric malignant tissue are intricately implicated in gastric cancer susceptibility, carcinogenesis, and the modulation of immunosurveillance and immune escape. These revelations offer fresh avenues for utilizing gastric microbiota as predictive biomarkers in clinical settings. Furthermore, inter-individual microbiota variations partially account for differential responses to cancer immunotherapy. In this review, we summarize current literature on the influence of the gastric microbiota on gastric carcinogenesis, anti-tumor immunity and immunotherapy, providing insights into potential clinical applications.

N-Nitrosamines: a potential hazard in processed meat products

Nitrite, nitrate, and their salts are added to processed meat products to improve color, flavor, and shelf life and to lower the microbial burden. N-Nitrosamine compounds are formed when nitrosing agents (such as secondary nitrosamines) in meat products interact with nitrites and nitrates that have been added to the meat. With the consumption of such meat products, nitrosation reactions occur in the human body and N-nitrosamine formation occurs in the gastrointestinal tract. Despite the benefits nitrites and nitrates have on food, their tendency to create nitrosamines and an increase in the body's nitrous amine load presents health risks. The inclusion of nitrosamine compounds in possible and probable carcinogen classes according to the International Agency for Research on Cancer requires a re-examination of the literature review on processed meat products. This article evaluates the connections between various cancer types and nitrosamines found in processed meat products. © 2023 Society of Chemical Industry.

C-Nitrosation, C-Nitration, and Coupling of Flavonoids with N-Acetyltryptophan Limit This Amine N-Nitrosation in a Simulated Cured and Cooked Meat

Nitrite is a common additive in cured meat formulation that provides microbiological safety, lipid oxidation management, and typical organoleptic properties. However, it is associated with the formation of carcinogenic N-nitrosamines. In this context, the antinitrosating capacity of selected flavonoids and ascorbate was evaluated in a simulated cooked and cured meat under formulation and digestion conditions. N-Acetyltryptophan was used as a secondary amine target. (-)-Epicatechin, rutin, and quercetin were all able to limit the formation of N-acetyl-N-nitrosotryptophan (NO-AcTrp) at pH 2.5 and pH 5 although (-)-epicatechin was 2 to 3-fold more efficient. Kinetics for the newly identified compounds allowed us to unravel common mechanistic pathways, which are flavonoid oxidation by nitrite followed by C-nitration and an original covalent coupling between NO-AcTrp and flavonoids or their nitro and nitroso counterparts. C-nitrosation of the A-ring was evidenced only for (-)-epicatechin. These major findings suggest that flavonoids could help to manage N-nitrosamine formation during cured meat processing, storage, and digestion.

A Comprehensive Review of Cured Meat Products in the Irish Market: Opportunities for Reformulation and Processing

Cured meat products constitute one of the meat categories commonly consumed in Ireland and has been part of the Irish cuisine and diet for many years. Ham, gammon, and bacon are some of the products that involve curing as part of the traditional processing methods. Common among these products are high levels of salt and the addition of nitrites. These products undergo processing treatments to create variety, preserve shelf-life, and develop their unique quality and safety characteristics. However, consumers are becoming more conscious of the level of processing involved in these products, and the effects of some components and ingredients might be perceived as unhealthy. Meat product developers have been exploring ways to reduce the amount of ingredients such as salt, saturated fat, and chemical preservatives (e.g., nitrites), which are linked to health concerns. This is a challenging task as these ingredients play an important techno-functional role in the products' quality, safety, and identity. While innovative processing techniques are being introduced and progress has been made in reformulation and packaging technologies, much is still unknown, especially regarding the applicability of many of the proposed interventions to a wide range of meat products and their sustainability at the industrial scale.

The comprehensive prediction of carcinogenic potency and tumorigenic dose (TD50) for two problematic N-nitrosamines in food: NMAMPA and NMAMBA using toxicology in silico methods

The identification and toxicological assessment of potential carcinogens is of paramount importance for public health and safety. This study aimed to predict the carcinogenic potency and tumorigenic dose (TD50) for two problematic N-nitrosamines (N-NAs) commonly found in food: N-2-methylpropyl-N-1-methylacetonylnitrosamine (NMAMPA, CAS: 93755-83-0) and N-3-Methylbutyl-N-1-methylacetonylnitrosamine (NMAMBA, CAS: 71016-15-4). To achieve this goal, in silico toxicology methods were employed due to their practical applications and potential in risk assessment. The justification for conducting these studies was incoherent results published by the European Food Safety Authority (EFSA). For this purpose, we applied various in silico tools, including qualitative methods (ToxTree, ProTox II and CarcinoPred-EL) and quantitative methods (QSAR Toolbox and LAZAR) were applied to predict the carcinogenic potency. These tools leverage computational approaches to analyze chemical structures for finding toxicophores and generating predictions, making them efficient alternatives to traditional in vivo experiments. The results obtained indicated that N-NAs are carcinogenic compounds, and quantitative data was obtained in the form of estimated doses of TD50 for the compounds tested.

Environmental Toxicology and Human Health

Humans and animals may be exposed on a continuous daily basis to a mixture of environmental contaminants that may act on several organ systems through differing mechanisms [...].

Development of Chinese-Style Sausage Enriched with Djulis (Chenopodium formosanum Koidz) Using Taguchi Method: Applying Modern Optimization to Indigenous People's Traditional Food

Djulis (Taiwanese quinoa) has gained popularity among researchers due to its biological characteristics and rich nutritional value. Incorporating Djulis is expected to enhance the sausage's texture, flavor, and storage stability due to the presence of antioxidants and nutritional components. However, limited studies focus on product development based on this emerging health-promoting ingredient in the food industry. This study aims to develop Chinese-style sausage enriched with Djulis using the Taguchi L9(34) orthogonal matrix methodology and evaluate the influence of four factors, including un-hulled to hulled Djulis ratios of 0, 50, 100% (A), backfat-to-lean meat ratios of 0/100, 30/70, 50/50% (B), cooking temperature of 55, 75, 95 °C (C), and nitrite content of 0.03, 0.05, 0.07 g/kg (D) on products' sensory and physicochemical properties. The optimal Taguchi formulation was then verified and compared with conventionally formulated sausage (original sausage) in terms of hardness, springiness, gumminess, CIE color values, and peroxide value (POV). The optimal formulation was A3B2C2D3, which consisted of 16.8% hulled Djulis, 30/70 backfat-to-lean meat ratio, 75 °C cooking temperature, and 0.03 g/kg nitrite content. The most influential independent parameters were identified as B > A > C > D, placing Djulis incorporation as the first runner-up, just after the backfat-to-lean meat ratio. Optimized condition verification identified the Signal-to-Noise ratio (S/N) of 16.63. Comparing the optimized Djulis-enriched sample and the original sausage indicated similar CIE L*, a*, b*, hardness, and springiness but different gumminess according to Texture Profile Analysis (TPA). The Djulis-enriched sausage at the optimized formulation had a significantly lower POV compared to the control sample (4.65 vs. 9.64 meq/kg), which was found to be correlated with Djulis antioxidant effects with 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) free radical antioxidant activity of 62.37%. This suggests that Djulis effectively mitigates sausage organoleptic deterioration. Djulis sausage, with natural antioxidants and reduced fat content, could cater to consumer preferences and enhance the market for the food industry and indigenous farmers.

Tumor Microbial Communities and Thyroid Cancer Development-The Protective Role of Antioxidant Nutrients: Application Strategies and Future Directions

Thyroid cancer (TC), the most frequent malignancy of the endocrine system, has recorded an increasing incidence in the last decades. The etiology of TC remains at least partly unknown and, among modifiable risk factors, the gut microbiota and dietary nutrients (vitamins, essential microelements, polyphenols, probiotics) have been recognized to not only influence thyroid function, but exert critical effects on TC development and progression. Recent discoveries on the existence of tumor microbiota also in the TC microenvironment provide further evidence for the essential role of tumor microorganisms in TC etiology and severity, as well as acting as prognostic markers and as a potential target of adjuvant care in the treatment of TC patients. Therefore, in this review, we summarize current knowledge on the relationship of the tumor microbiome with the clinical tumor characteristics and TC progression, also illustrating the molecular mechanisms underlying this association, and how antioxidant nutrients may be used as a novel strategy to both control gut health and reduce the risk for TC. Furthermore, we discuss how new technologies might be exploited for the development of new foods with high nutritional values, antioxidant capability, and even attractiveness to the individual in terms of sensory and emotional features.

LDHA and LDHB overexpression promoted the Warburg effect in malignantly transformed GES-1 cells induced by N-nitroso compounds

N-nitroso compounds (NOCs) exposure is a major risk factor for the development of gastric cancer. However, the carcinogenic mechanisms by which NOCs induce gastric and other cancers, especially the NOCs-induced Warburg effect, have not been comprehensively studied. Lactate dehydrogenase (LDH), which has two subunits (LDHA and LDHB), plays an important role in the Warburg effect of tumor cells. Therefore, we hypothesized that LDHA and LDHB could promote Warburg effect in malignant transformed GES-1 cells induced by Nmethyl-N'-nitro-N-nitrosoguanidine (MNNG). GES-1 cells were exposed to 1 μmol/L MNNG and cultured for 40 passages. During the culturing process, cell proliferation, migration, and soft agar colony formation significantly increased after 30 passages. Following MNNG exposure, lactate, LDH, glucose uptake, and the expression levels of key enzymes in glycolysis were significantly increased. Knocking down LDHA or LDHB alone reduced lactate secretion, inhibited cell viability, and impaired migratory capacities. Knocking down LDHA and LDHB together fully suppressed lactate secretion and effectively suppressed the malignant phenotype of cells transformed by long-term MNNG exposure. Finally, we demonstrated that overexpression of LDHA and LDHB promotes the malignant transformation of GES-1 cells by enhancing the Warburg effect during long-term exposure to NOCs.

Positive feedback loop between dietary nitrate intake and oral health

Nitrate was once thought to be an inert end-product of endothelial-derived nitric oxide (NO) heme oxidation; however, this view has been radically revised over the past few decades. Following the clarification of the nitrate-nitrite-NO pathway, accumulated evidence has shown that nitrate derived from the diet is a supplementary source of endogenous NO generation, playing important roles in a variety of pathological and physiological conditions. However, the beneficial effects of nitrate are closely related with oral health, and oral dysfunction has an adverse effect on nitrate metabolism and further impacts overall systemic health. Moreover, an interesting positive feedback loop has been identified between dietary nitrate intake and oral health. Dietary nitrate's beneficial effect on oral health may further improve its bioavailability and promote overall systemic well-being. This review aims to provide a detailed description of the functions of dietary nitrate, with an emphasis on the key role oral health plays in nitrate bioavailability. This review also provides recommendations for a new paradigm that includes nitrate therapy in the treatment of oral diseases.

Leafy Vegetable Nitrite and Nitrate Content: Potential Health Effects

The aim of this research was to determine the concentrations of nitrates and nitrites in different types of vegetables that are commonly represented in the diet of the inhabitants of Split and Dalmatian County. Therefore, using the method of random selection, there were 96 samples of different vegetables. The determination of the nitrate and nitrite concentrations was carried out by high-pressure liquid chromatography (HPLC) with a diode array detector (DAD). The nitrate concentrations in the range 2.1-4526.3 mg kg^-1 were found in 92.7% of the analyzed samples. The highest nitrate values were found in rucola (Eruca sativa L.) followed by Swiss chard (Beta vulgaris L.). In 36.5% of the leafy vegetables intended for consumption without prior heat treatment, nitrite was found in the range of 3.3-537.9 mg kg^-1. The high levels of nitrite in the vegetables intended for fresh consumption and the high nitrate values in Swiss chard indicate the need to establish maximum nitrite limits in vegetables, as well as the broadening of legal nitrate limits to wide varieties of vegetables.