Plasma Alkylresorcinols Reflect Gluten Intake and Distinguish between Gluten-Rich and Gluten-Poor Diets in a Population at Risk of Metabolic Syndrome

Selective determination of 3,5-dihydroxycinnamic acid in urine samples as gluten intake biomarker: high-performance thin-layer chromatography combined with colorimetric detection

The determination of biomarkers is a significant field of analytical chemistry research under continuous evolution that contributes to enhance diagnostics and enable more personalized medicine. Celiac disease is a systemic autoimmune disorder caused by the ingestion of gluten (Glu) proteins found in various cereals. Currently, the only effective way to prevent and manage potential complications is through a strict gluten-free diet (GFD). However, both intentional and unintentional dietary transgressions can occur, often leading to persistent symptoms and ineffective treatment. In this scenario, the development of analytical strategies to detect biomarkers of gluten intake and monitor adherence to a GFD is of significant interest. Herein, we present an analytical strategy based on high-performance thin-layer chromatography (HPTLC) combined with colorimetric detection to estimate 3,5-dihydroxycinnamic acid (3,5-DHCA) as selective biomarker of Glu intake in urine. The approach combined Fast Blue (FB)-doped polydimethylsiloxane (PDMS) membrane with colorimetric HPTLC (RP-C18) giving rise to a selective method to isolate 3,5-DHCA response in urine samples. Detection by visual inspection, image analysis, and spectroscopic response was evaluated and compared. Analytical parameters were estimated showing a good sensitivity (limit of detection (LOD) ≤ 0.8 mg L-1) and precision, relative standard deviation (RSD) values < 7%. Analysis of urine samples of celiac patients and control patients was performed, and recovery studies showed satisfactory values (R > 80%). The preliminary results indicated correlation between Glu intake and positive 3,5-DHCA responses. This study demonstrated that FB-doped PDMS membranes-HPTLC is a promising tool for detecting dietary transgressions to the GFD by visual inspection, and subsequent quantitative analysis by image analysis and spectroscopic techniques. Hence, the proposed analytical method contributes to the advance of knowledge about celiac disease, which still remains an important challenge to our society.

Plasma Alkylresorcinols is an objective biomarker for gluten intake in young children

BACKGROUND

Alkylresorcinols are a well-established biomarker for whole grain intake. There is evidence suggesting that total plasma alkylresorcinol concentration may also be used as a biomarker for gluten intake in adults.

OBJECTIVE

The aim of the study was to evaluate if total alkylresorcinol concentration is a valid biomarker for gluten intake in young children.

METHODS

Non-fasting plasma alkylresorcinol concentrations were analyzed by normal-phase ultra-high pressure liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) in 65 children aged 18 months included in a randomized controlled trial. The intervention group was following a gluten-free diet (n=21, 31.3%), while the diet was unrestricted in the control group (n=44, 65.7%). Alkylresorcinol concentrations in the 65 children were validated against simultaneously collected 3-day food records estimating total gluten intake.

RESULTS

Gluten intake in controls was median 5.8 grams (g)/day (inter quartile range [IQR] 2.8-9.4, max 17.1) compared to 0.0 g/day (IQR 0.0-0.0, max 0.7, p<0.001) in the intervention group. In the control group, wheat accounted for mean 85% (standard deviations [SD] 0.1) of the gluten intake. The intervention group had lower alkylresorcinol levels (median 7.2 nmol/L, IQR 4.0-10.5) compared to controls (median 269, IQR 116-505 nmol/L, p<0.001). The correlation between alkylresorcinol concentrations and gluten intake was rho=0.68 (p<0.001). Alkylresorcinol concentrations increased by 35.7% (95% confidence interval [CI] 25.9, 46.2, p<0.001) for every g/day increase of gluten intake. The Cohen's weighted kappa between quartiles of alkylresorcinol and gluten intake was 0.73 (95% CI 0.59, 0.86).

CONCLUSIONS

Alkylresorcinol concentrations increased with gluten intake in young non-fasting children. The findings suggest that alkylresorcinol concentrations may be a useful biomarker for gluten intake in young children.

CLINICAL TRIAL REGISTRY

ClinicalTrials.gov Identifier NCT03562221.

Metabolic fingerprinting using Rapid evaporative ionisation mass spectrometry can discriminate meat quality and composition of lambs from different sexes, breeds and forage systems

Assurance of food quality and allied farming systems is increasingly sought by consumers and food processors. Yet, there are no validated analytical approaches for food-based verification of farming systems. Rapid evaporative ionisation mass spectrometry (REIMS) is an emerging analytical tool that can provide sufficient details to meet this need. M. Longissimus lumborum of 10 groups of lambs (n = 140) from 3 farms, varying by breed, sex, and forage type, were measured using REIMS fingerprinting. Modelling of features detected by REIMS could discriminate for most comparisons of sex (including castration status), breed, and diet. Tentative identification suggested that lipids, hormone-related compounds, amino acids and dipeptides were the main discriminatory features. Several REIMS features were correlated with pH and shear force in Merino lambs. REIMS was able to detect features related to breed, sex and feed in lamb meat, suggesting that these characteristics can be independently measured using rapid metabolic fingerprinting.

An Overview of Alkylresorcinols Biological Properties and Effects

The investigation of alkylresorcinols has drawn an increasing interest recently. Alkylresorcinols (ARs) are natural chemical compounds synthesized by bacteria, fungi, sponges, and higher plants, possessing a lipophilic polyphenol structures and a myriad of biological properties. Human takes ARs as a component of a whole grain diet (from whole grain rye, wheat, and barley products), and thus, alkylresorcinols are frequently used as whole grain intake markers. Besides, ARs are considered as promising bioregulators of metabolic and immune processes, as well as adjuvant therapeutic agents for antimicrobial and anticancer treatment. In this review, we attempted to systematize the accumulated information concerning ARs origin, metabolism, biological properties, and their effect on human health.

Biomarkers of cereal food intake

Background/objectives

Cereal foods are major contributors to the daily energy, protein, and dietary fiber intake all over the world. The role of cereals in human health is dependent on whether they are consumed as refined or whole grain and on cereal species. To unravel the underlying mechanisms of health effects attributed to specific cereal foods and to provide more precise dietary advice, there is a need for improved dietary assessment of whole-grain intake. Dietary biomarkers of specific cereals, different fractions or cereal-containing foods could offer such a possibility. The aim of this review was to summarize the current status on biomarkers of different cereals, fractions, and specific cereal foods.

Subjects and methods

A literature review was conducted and putative biomarkers of different cereals and pseudo-cereals (wheat, oats, rye, barley, rice, and quinoa) as well as for different grain fractions (whole grain, refined grain, bran) and foods were summarized and discussed.

Results

Several putative biomarkers have been suggested for different cereals, due to their unique presence in these grains. Among the biomarkers, odd-numbered alkylresorcinols are the most well-studied and -evaluated biomarkers and reflect whole-grain wheat and rye intake. Even-numbered alkylresorcinols have been suggested to reflect quinoa intake. Recent studies have also highlighted the potential of avenanthramides and avenacosides as specific biomarkers of oat intake, and a set of biomarkers have been suggested to reflect rice bran intake. However, there are yet no specific biomarkers of refined grains. Most biomarker candidates remain to be evaluated in controlled interventions and free-living populations before applied as biomarkers of intake in food and health studies.

Conclusion

Several putative biomarkers of different cereals have been suggested and should be validated in human studies using recently developed food intake biomarker validation criteria.

Detection and quantification of gluten immunogenic peptides in feces of infants and their relationship with diet

BACKGROUND

there are no effective methods to easily control the correct adherence to a gluten-free diet (GFD) in celiac disease (CD) patients.

AIM

to assess the sensitivity and specificity of a rapid immunochromatographic (IC) test that detects gluten immunogenic peptides (GIP) in feces, compared to an enzyme-linked immunosorbent assay (ELISA) method.

METHODS

fecal samples from healthy infants were analyzed by a rapid IC test and ELISA, both methods are based on the anti-gliadin 33-mer monoclonal antibody. Group 1 included infants aged from 6 to 24 months, with an unrestricted consumption of gluten containing cereals. Group 2 (negative controls) was comprised of infants aged from 0 to 6 months, either breastfed or formula fed who had never ingested gluten.

RESULTS

in group 1 (n = 34), all infants had positive values by ELISA, the mean was 13.13 μgGIP/g (range 0.56-46.79). The IC test was negative in 5/20 cases and there was a significant correlation (p=0.006) between the mean daily gluten intake and GIP in feces. In group 2 (n = 20), all the samples were negative by both methods. Moreover, the Kappa Fleiss concordance index (Kappa = 0.79 CI95% [0.616, 0.965]) indicated a moderate concordance between both methods.

CONCLUSIONS

according to our results, both methods are highly specific. However, the ELISA test had a higher sensitivity. Although we found a significant correlation between the amount of gluten consumed and GIP recovery in feces, further studies are needed to clarify the impact of individual confounding factors in GIP recovery.

A low-gluten diet induces changes in the intestinal microbiome of healthy Danish adults

Adherence to a low-gluten diet has become increasingly common in parts of the general population. However, the effects of reducing gluten-rich food items including wheat, barley and rye cereals in healthy adults are unclear. Here, we undertook a randomised, controlled, cross-over trial involving 60 middle-aged Danish adults without known disorders with two 8-week interventions comparing a low-gluten diet (2 g gluten per day) and a high-gluten diet (18 g gluten per day), separated by a washout period of at least six weeks with habitual diet (12 g gluten per day). We find that, in comparison with a high-gluten diet, a low-gluten diet induces moderate changes in the intestinal microbiome, reduces fasting and postprandial hydrogen exhalation, and leads to improvements in self-reported bloating. These observations suggest that most of the effects of a low-gluten diet in non-coeliac adults may be driven by qualitative changes in dietary fibres.

Gluten-free diets are increasingly common in the general population. Here, the authors report the results of a randomised cross-over trial involving middle-aged, healthy Danish adults, showing evidence that a low-gluten diet leads to gut microbiome changes, possibly due to variations in dietary fibres.

The Effect of Gluten Free Diet on Components of Metabolic Syndrome: A Randomized Clinical Trial

Background:

This study aimed to assess the effects of Gluten free diet (GFD) on components of metabolic syndrome (MES).

Materials and Methods:

In this randomized clinical trial, 50 subjects diagnosed with MES were randomly divided into two groups (n=25). The first group received a GFD and the second group continued their regular diet. Biochemical markers of MES and blood pressure were measured before and after 8-week intervention.

Results:

Forty five subjects completed the study. A post-hoc comparison of the groups showed no effects of the GFD and control diet on LDL cholesterol, total cholesterol, fasting insulin, HOMA-IR, systolic and diastolic blood pressure levels. The GFD reduced fasting blood glucose, waist circumference (WC) and serum triglyceride concentration significantly compared with the control diet (p<0.05).

Conclusion:

Short-term GFD reduced WC and improved glycemic control and Triglyceride level in subjects with the metabolic syndrome.

Serum alkylresorcinols as biomarkers of dietary gluten exposure in coeliac disease

BACKGROUND

Therapy for coeliac disease (CD) mainly relies on following a gluten-free diet (GFD); however, a serum marker for gluten intake has yet to be established.

AIM

To evaluate the utility of alkylresorcinol concentrations for detecting gluten intake in studies of human and mouse.

METHODS

Alkylresorcinol concentrations were compared among treated patients with coeliac disease (n = 34), untreated coeliac disease patients (n = 36) and controls (n = 33). Furthermore, seven additional coeliac disease patients whose serum samples were available at diagnosis and after GFD were evaluated. In mice studies, alkylresorcinol concentrations were compared in the serum of five mice fed a regular chow and 10 mice fed lifelong with a gluten-free chow. In addition, the effect of adding gluten on changes of alkylresorcinol concentrations was also evaluated.

RESULTS

Total alkylresorcinol concentrations were significantly lower in treated with coeliac disease [median (IQR), 3 (2-8) nmol/L], compared to untreated patients [median (IQR), 32 (11-74) nmol/L; P < 0.0001] or healthy controls [median (IQR), 54 (23-112) nmol/L; P < 0.0001]. Moreover, alkylresorcinol concentrations in coeliac disease patients significantly decreased after introduction of a GFD (median, 34 nmol/L at diagnosis vs. 5 nmol/L after GFD, P = 0.02). In the mice, median (IQR) total alkylresorcinol concentrations in serum samples of mice fed lifelong with a gluten-free chow was 1.8 (1.6-2.3) nmol/L, which was further significantly increased to 16 (11-22) nmol/L after 8 days of feeding with the gluten-free chow that had gluten added to it. (P = 0.008).

CONCLUSION

Serum alkylresorcinol concentrations could be a useful marker for dietary gluten in coeliac disease.

A High Rate of Non-Compliance Confounds the Study of Whole Grains and Weight Maintenance in a Randomised Intervention Trial-The Case for Greater Use of Dietary Biomarkers in Nutrition Intervention Studies

Observational studies consistently find an inverse relationship between whole-grain intake and weight gain. We aimed to confirm this in an open-label researcher-blinded parallel design randomised trial. A total of 179 overweight/obese women with a habitually low whole-grain intake (<16 g/day) were randomised to a weight maintenance diet with refined-grain (RG) or whole-grain (WG) foods (80 g/day) for 12 weeks after an initial weight loss program over 8 weeks. Body weight and composition was assessed at baseline, after the initial weight loss, and after the 12-week dietary intervention. During the 12-week dietary intervention phase, there were no group differences in changes in body weight and total fat mass %, whereas abdominal fat mass tended to increase more during the dietary intervention phase in the WG compared to the RG group (0.7 (SD 3.6) vs. −0.3 (SD 3.8) %; p = 0.052). Plasma alkylresorcinol concentrations, biomarkers of wholegrain wheat and rye intake, indicated poor compliance, particularly in the WG group, where >60% of participants had alkylresorcinol concentrations below 70 nmol/L, a concentration indicating low or no intake of whole-grain wheat. Further, weight regain was lower than expected in both intervention groups, further supporting a lack of compliance to the post-weight-loss diet. The rate of compliance was too low to conclude any effect of whole grain on weight maintenance, and reinforces the need to use objective measures of compliance in nutrition intervention studies.

Biomarkers to Monitor Gluten-Free Diet Compliance in Celiac Patients

Gluten-free diet (GFD) is the only treatment for celiac disease (CD). There is a general consensus that strict GFD adherence in CD patients leads to full clinical and histological remission accompanied by improvement in quality of life and reduced long-term complications. Despite the importance of monitoring the GFD, there are no clear guidelines for assessing the outcome or for exploring its adherence. Available methods are insufficiently accurate to identify occasional gluten exposure that may cause intestinal mucosal damage. Serological tests are highly sensitive and specific for diagnosis, but do not predict recovery and are not useful for follow-up. The use of serial endoscopies, it is invasive and impractical for frequent monitoring, and dietary interview can be subjective. Therefore, the detection of gluten immunogenic peptides (GIP) in feces and urine have been proposed as new non-invasive biomarkers to detect gluten intake and verify GFD compliance in CD patients. These simple immunoassays in human samples could overcome some key unresolved scientific and clinical problems in CD management. It is a significant advance that opens up new possibilities for the clinicians to evaluate the CD treatment, GFD compliance, and improvement in the quality of life of CD patients.