Carbon and nitrogen stable isotopes in U.S. milk: Insight into production process

The Carbon Isotope Ratio as an Objective Biomarker of Added Sugar Intake: A Scoping Review of Current Evidence in Human Nutrition

Objective biomarkers of dietary intake are needed to advance nutrition research. The carbon isotope ratio (C13/C12; CIR) holds promise as an objective biomarker of added sugar (AS) and sugar-sweetened beverage (SSB) intake. This systematic scoping review presents the current evidence on CIRs from human studies. Search results (through April 12, 2024) yielded 6297 studies and 24 final articles. Studies were observational (n = 12), controlled feeding (n = 10), or dietary interventions (n = 2). CIRs were sampled from blood (n = 23), hair (n = 5), breath (n = 2), and/or adipose tissue (n = 1). Most (n = 17) conducted whole tissue (that is, bulk) analysis, 8 used compound specific isotope analysis (CSIA), and/or 2 studies used methods appropriate for analyzing breath. Studies were conducted in 3 concentrated geographic regions of the United States (n = 7 Virginia; n = 5 Arizona; n = 4 Alaska), with only 2 studies conducted in other countries. Studies that used CSIA to examine the CIR from the amino acid alanine (CIR-Ala; n = 4) and CIR analyzed from breath (n = 2) provided the most robust evidence for CIR as an objective biomarker of AS and SSBs (R2 range 0.36-0.91). Studies using bulk analysis of hair or blood showed positive, but modest and more variable associations with AS and SSBs (R2 range 0.05-0.48). Few studies showed no association, particularly in non-United States populations and those with low AS and SSB intakes. Two studies provided evidence for CIR to detect changes in SSB intake in response to dietary interventions. Overall, the most compelling evidence supports CIR-Ala as an objective indicator of AS intake and breath CIR as an indicator of short-term AS intake. Considering how to adjust for underlying dietary patterns remains an important area of future work and emerging methods using breath and CSIA warrant additional investigation. More evidence is needed to refine the utility and specificity of CIRs to measure AS and SSB intake.

Effects of sampling time and location on the geographical origin traceability of protected geographical indication (PGI) Hongyuan yak milk: Based on stable isotope ratios

Hongyuan yak milk is a protected geographical indication (PGI) product of rich nutritional value, which is popular among consumers. Stable isotope ratio analysis (SIRA) is an effective way to protect the authenticity of the geographical origin of PGI products, and it is crucial to study the factors affecting stable isotopes. Firstly, we proved that the SIRA could be used to identify the geographical origin of Hongyuan yak milk, and that the identification accuracy in combination with δ13C and δ18O was 100 %. Secondly, we analyzed the effect of sampling selection on the stable isotopes of Hongyuan yak milk in practical applications, which showed that sampling time influenced the δ13C, δ2H, and δ18O, while the sampling locations did not. There were interactions between the effect of sampling time and location on δ2H and δ18O. These results provide a reliable method for identifying PGI products and also provide new guidance on sampling models.

Determination of adulteration, geographical origins, and species of food by mass spectrometry

Food adulteration, mislabeling, and fraud, are rising global issues. Therefore, a number of precise and reliable analytical instruments and approaches have been proposed to ensure the authenticity and accurate labeling of food and food products by confirming that the constituents of foodstuffs are of the kind and quality claimed by the seller and manufacturer. Traditional techniques (e.g., genomics-based methods) are still in use; however, emerging approaches like mass spectrometry (MS)-based technologies are being actively developed to supplement or supersede current methods for authentication of a variety of food commodities and products. This review provides a critical assessment of recent advances in food authentication, including MS-based metabolomics, proteomics and other approaches.

Isotope Fingerprinting as a Backup for Modern Safety and Traceability Systems in the Animal-Derived Food Chain

In recent years, due to the globalization of food trade and certified agro-food products, the authenticity and traceability of food have received increasing attention. As a result, opportunities for fraudulent practices arise, highlighting the need to protect consumers from economic and health damages. In this regard, specific analytical techniques have been optimized and implemented to support the integrity of the food chain, such as those targeting different isotopes and their ratios. This review article explores the scientific progress of the last decade in the study of the isotopic identity card of food of animal origin, provides the reader with an overview of its application, and focuses on whether the combination of isotopes with other markers increases confidence and robustness in food authenticity testing. To this purpose, a total of 135 studies analyzing fish and seafood, meat, eggs, milk, and dairy products, and aiming to examine the relation between isotopic ratios and the geographical provenance, feeding regime, production method, and seasonality were reviewed. Current trends and major research achievements in the field were discussed and commented on in detail, pointing out advantages and drawbacks typically associated with this analytical approach and arguing future improvements and changes that need to be made to recognize it as a standard and validated method for fraud mitigation and safety control in the sector of food of animal origin.

Breath 13CO2-evidence for a noninvasive biomarker to measure added refined sugar uptake

Increased consumption of added sucrose and high-fructose corn syrup in the human diet has been associated with increasing incidence of obesity and metabolic disease. There are currently no reliable, objective biomarkers for added sugar intake that could be used in individuals or population settings. 13C is a stable isotope of carbon, and measurement of blood 13C content has been proposed as a marker of added sugar consumption. This study aimed to determine if breath 13CO2 could represent an alternative, noninvasive biomarker to monitor added sugar intake. We undertook retrospective analyses of eight preclinical and human 13C-breath studies to define baseline breath 13CO2 characteristics. All samples were analyzed using isotope ratio mass spectrometry, and breath 13CO2 was expressed as the delta value, δ expressed as parts per thousand (‰). All data are expressed as mean ± SEM, with statistical significance considered at P < 0.05. Breath δ13CO2 was significantly elevated in a cumulative manner in rats and mice that consumed a diet containing at least 15% sucrose. Mice fed an American rodent chow diet containing 50% sucrose and 15% corn starch had a significantly higher breath δ13CO2 compared with rodents consuming an Australian rodent chow diet. Furthermore, breath δ13CO2 was significantly increased in a dose-dependent manner in humans that ingested a bolus dose of sucrose. These findings suggest application for baseline breath δ13CO2 as a noninvasive biomarker for added sugar consumption, with broad application for longitudinal assessment of population sugar intake and obesity management strategies.NEW & NOTEWORTHY We have found that breath 13CO2 is increased in rats and mice consuming diets high in sucrose. We also found that human breath 13CO2 is increased in humans consuming increasing amounts of sucrose. Our collective findings suggest that breath 13CO2 represents a potential marker of added dietary sugar consumption.

Natural abundance carbon isotope ratio analysis and its application in the study of diet and metabolism

Due to differences in carbon assimilation pathways between plants, there are subtle but distinct variations in the carbon isotope ratios of foods and animal products throughout the food supply. Although it is well understood that the carbon isotope ratio composition of the diet influences that of the consumers' tissues, the application of natural abundance carbon isotope ratio analysis in nutrition has long been underappreciated. Over the past decade, however, several studies have investigated the utility of carbon isotope ratio analysis for evaluation of nutritional biomarker status, primarily focusing on its application as an objective indicator of sugar and animal protein intake. More recently, research investigating the application of natural abundance measurements has been extended to study fatty acid metabolism and has yielded encouraging results. Collectively, data from large-scale observational studies and experimental animal studies highlight the potential for carbon isotope ratio analysis as an additional and effective tool to study diet and metabolism. The purpose of this review is to provide an overview of natural abundance carbon isotope ratio analysis, its application to studying nutrition, and an update of the research in the field.

Application and Preparation Progress of Stable Isotope Reference Materials in Traceability of Agricultural Products

In the field of food traceability analysis, stable isotope ratio analysis is a relatively new technology. The measurement and calibration of isotope data depends on stable isotope reference materials. The isotope reference materials commonly used are chemical matrix. These reference materials are inappropriate-especially for food matrix origin analysis. This review focuses on the research progress on stable isotope reference materials by (1) classification of stable isotope reference materials, (2) application of stable isotope reference materials, and (3) research progress of preparation of stable isotope reference materials. Selecting appropriate isotope reference materials will help improve the effectiveness of stable isotope ratio analysis in food traceability. By cooperation with different laboratories, high-quality isotope reference materials can be prepared to add new food matrix types to provide more choices for users.

Investigation into the Concentrations and Sources of Nitrates and Nitrites in Milk and Plant-Based Powders

Milk powders in the United States (US) may contain nitrates and nitrites from several potential sources. These sources include the ingestion of nitrates and nitrites by dairy cows during grazing and drinking, nitric acid used during the sanitization of dairy equipment, and the production of nitrous oxides in directly heated spray dryers. Recently, milk powders manufactured in the US have been rejected during import to other countries because nitrite concentrations were greater than 2 mg/kg (ppm). To date, the concentrations of nitrates and nitrites in milk and plant-based powders in the US are unknown. In this study the nitrate and nitrite concentrations present in diverse milk powders were investigated including 81 milk powders from local and online retailers from 2015 to 2018. In addition, 71 commercial milk powders were obtained from blinded production facilities. Nitrate and nitrite concentrations were determined using ion chromatography with conductivity and UV detection. A subset of samples was analyzed for N-nitrosodimethylamine using gas chromatography-mass spectrometry. Carbon and nitrogen bulk isotope ratios analyzed using isotope ratio mass spectrometry were used to obtain some insights into the production method (organic vs conventional) and geographic source of the milk powder samples. Background nitrate concentrations in US-produced milk powder samples averaged 17 ± 12 mg/kg. Nitrite was detected at concentrations greater than 2 mg/kg in 5 out of 39 different brands of retail milk and plant-based powders. Of these brands, two were plant-based (soy and coconut) powders and the other three had consistently high nitrites. The analysis of milk powders using stable isotope analysis revealed further information about the cow's diet.

Application of multi-element (C, N, H, O) stable isotope ratio analysis for the traceability of milk samples from China

Cow milk samples from various provinces in China were collected, and the effects of lactation stage, sampling time, and geographic origin on the samples were studied by elemental analysis-isotope ratio mass spectrometry (EA-IRMS). Traceability accuracy was determined using δ¹³C, δ¹⁵N, δ²H and δ¹⁸O values to specifically assign geographic origin. Stable isotope ratios of C, N, H and O were not significantly different among three lactation stages; however the δ¹³C, δ¹⁵N, and δ¹⁸O values of milk were influenced by sampling time. Furthermore, there were highly significant regional differences in the mean δ¹³C and δ¹⁵N values of milk. In summary, the lactation stage had no effect on the traceability of milk, whereas sampling time and geographic origin did affect milk traceability. Different geographic locations with a separation distance greater than 0.7 km can be distinguished using multi-element (C, N, H, O) stable isotope ratio analysis.