Comparison of salivary proteome of children with different sensitivities for bitter and sweet tastes: association with body mass index

The gustin gene variation at rs2274333 and PROP taster status affect dietary fat perception: a stepwise multiple regression model study

Gustin, a trophic factor for taste bud development, and its polymorphism at rs2274333 influence taste perception of 6-n-propylthiouracil (PROP) and fungiform papillae (FP) density. The PROP taster status affects dietary fat sensing and body composition. However, there is a paucity of research on the gustin genotype with dietary fat perception, PROP tasting ability, and body mass index (BMI). Thus, taste sensitivity to fat and bitterness was evaluated in 178 healthy individuals. The general labeled magnitude scale was used to determine suprathreshold taste intensity ratings, whereas the alternative forced choice approach was used to estimate the taste-sensing ability. The FP density was assessed by applying blue-colored food dye over the anterior region of the tongue. Restriction fragment length polymorphism was used to detect the genetic polymorphism (rs2274333) in the carbonic anhydrase VI (CA-VI) gene. Fisher's chi-square analysis showed that the CA-VI genotype and allelic frequencies significantly correlated (p<0.001) with the PROP taster status and BMI. Healthy individuals with AA genotypes of the CA-VI polymorphism and PROP super-tasters demonstrated stronger gustatory sensitivity for linoleic acid (LA) with greater FP density in comparison to individuals with AG/GG genotypes and other PROP taster groups. Stepwise forward multiple regression analysis indicates that BMI and PROP taster status significantly influence the LA sensing ability. The suprathreshold intensity rating for LA was also significantly impacted by PROP taster status and CA-VI genotypes, with a variation of 73.3%. Overall, our findings show a relationship between the taste papillae environment and the CA-VI genetic mutation at rs2274333, which influenced the gustatory preference for dietary fat and bitter taste.

The Influence of (Poly)phenol Intake in Saliva Proteome: Short- and Medium-Term Effects of Apple

The relationship between salivary proteome and dietary habits was studied in previous works, where a relationship between salivary proteins like cystatins and polyphenol/tannin levels in diet was observed. However, it remains to be elucidated if this association results from an effect of polyphenol-rich food ingestion on saliva composition. The aim of this work was to test the effects of apple intake on the saliva proteome, both in the short and medium term (after 4 days of continuous intake). By incubating saliva samples with apple phenolic-rich extract, protein bands containing α-amylase, S-type cystatins, and proline-rich proteins (PRPs) appeared in the fraction that precipitated, showing the potential of these (poly)phenols to precipitate salivary proteins. Among these, it was salivary cystatins that presented changes in their levels both in the saliva samples collected immediately after apple intake and in the ones collected after 4 days of intake of an extra amount of apple. These results support the thought that intake is reflected in the salivary proteome. The effect of a polyphenol-rich food, like the apple, on salivary cystatin levels is in line with results observed in animal models and, due to the involvement of these proteins in oral food perception, it would be interesting to explore in future studies the effect of these changes on sensory perception and acceptance of polyphenol-rich food.

Salivary proteomic analysis in asymptomatic and symptomatic SARS-CoV-2 infection: Innate immunity, taste perception and FABP5 proteins make the difference

BACKGROUND AND AIM

SARS-CoV-2 infection spawns from an asymptomatic condition to a fatal disease. Age, comorbidities, and several blood biomarkers are associated with infection outcome. We searched for biomarkers by untargeted and targeted proteomic analysis of saliva, a source of viral particles and host proteins.

METHODS

Saliva samples from 19 asymptomatic and 16 symptomatic SARS-CoV-2 infected subjects, and 20 controls were analyzed by LC-MS/MS for untargeted peptidomic (flow through of 10 kDa filter) and proteomic (trypsin digestion of filter retained proteins) profiling.

RESULTS

Peptides from 53 salivary proteins were identified. ADF was detected only in controls, while IL1RA only in infected subjects. PRPs, DSC2, FABP5, his-1, IL1RA, PRH1, STATH, SMR3B, ANXA1, MUC7, ACTN4, IGKV1-33 and TGM3 were significantly different between asymptomatic and symptomatic subjects. Retained proteins were 117, being 11 highly different between asymptomatic and symptomatic (fold change ≥2 or ≤-2). After validation by LC-MS/MS-SRM (selected reaction monitoring analysis), the most significant discriminant proteins at PCA were IL1RA, CYSTB, S100A8, S100A9, CA6, and FABP5.

CONCLUSIONS

The differentially abundant proteins involved in innate immunity (S100 proteins), taste (CA6 and cystatins), and viral binding to the host (FABP5), appear to be of interest for use as potential biomarkers and drugs targets.

Holistic approach to effects of foods, human physiology, and psychology on food intake and appetite (satiation & satiety)

Appetite (satiation and satiety) is an essential element for the control of eating behavior, and as a consequence human nutrition, body weight, and chronic disease risk. A better understanding of appetite mechanisms is necessary to modulate eating behavior and food intake, and also provide a practical approach for weight management. Although many researchers have investigated the relationships between satiation/satiety and specific factors including human physiology, psychology, and food characteristics, limited information on the interactions between factors or comparisons between the relative importance of factors in contributing to satiation/satiety have been reported. This article reviews progress and gaps in understanding individual attributes contributing to perceived satiation/satiety, the advantages of considering multiple factors together in appetite experiments, as well as the applications of nondestructive sensing in evaluating human factors contributing to relative appetite perception. The approaches proposed position characterization of appetite (satiation and satiety) for personalized and precision nutrition in relation to human status and healthy diets. In particular, it is recommended that future studies of appetite perception recognize the inter-dependence of food type and intake, appetite (satiation and satiety), and individual status.

Exploration of Malaysian school-children's food preferences: what do we know?

BACKGROUND

Feeding practices exert a definite influence over children's experiences. This article aims to explore parental feeding practices and investigate the prediction domain of food preference from parent-child perspectives.

METHODS

Two individual studies were conducted on Malay families with children aged 7-12 years. In Study 1, mothers (n = 17) participated in semi-structured focus group interviews on their knowledge of foods and feeding practices. In Study 2, parent-child pairs (n = 14) answered a 36-item, 5-point Likert scale Food Preference Questionnaire followed by virtual structured qualitative interviews. The interviews were digitally recorded, transcribed verbatim, back-translated and analysed according to the framework analysis technique.

RESULTS

In Study 1, mothers perceived vegetables, chicken, fish and plain water as healthy foods and drinks while discretionary options were snacks, fast foods and carbonated drinks. The mothers defined healthy foods as foods handled safely with health benefits. They used 'healthy' cooking methods to prepare preferred foods and overtly controlled the child's access to discretionary food. In Study 2, the food groups reported by parent-child pair's report were consistent for the most preferred foods [snacks, median (interquartile range), parent: 4.5 (1.0) vs. child: 4.5 (0.0), p &gt; 0.05] and least preferred food [legumes, parent: 2.0 (1.0) vs. child: 2.0 (1.0), p &gt; 0.05]. Parents emphasized taste as the key determinant of food preference.

CONCLUSION

These studies were the first to qualitatively explore parents' perceptions of foods affecting their feeding practices among the Malaysian community to highlight the cultural contribution. Key insights into children's food intake and factors influencing their food preferences were identified.

Effect of thermal and chemical treatments used for SARS-COV-2 inactivation in the measurement of saliva analytes

The present study aims to assess the effects of thermal and chemical inactivating procedures, that can be used for SARS-CoV-2 inactivation, on different salivary analytes. SDS–Polyacrylamide Gel Electrophoresis (SDS-PAGE) protein profile and a panel of 25 specific biomarkers of oxidative status, stress, metabolism and tissue damage were evaluated in samples subjected to different treatments: thermal (65 °C or 92 °C) and chemical with detergents [sodium dodecyl sulphate (SDS), Triton X-100 or NP-40]. Salivary SDS-PAGE profile was most affected by heating at 92 °C, with three and two protein bands decreasing and increasing their expression levels, respectively. This treatment also affected the results of several enzymes, with some of them being also affected by heating at 65 °C and incubation with SDS. The use of Triton X-100 or NP-40 resulted in increased values of cortisol, triglycerides and glucose, not affecting the other tested biomarkers. The present results will help researchers and clinicians to select the best protocols to work in safe conditions with saliva, taking into account the target analyte planned to be measured.

Taste Sensitivity and Taste Preference among Malay Children Aged 7 to 12 Years in Kuala Lumpur-A Pilot Study

The taste and food preferences in children can affect their food intake and body weight. Bitter and sweet taste sensitivities were identified as primary taste contributors to children's preference for consuming various foods. This pilot study aimed to determine the taste sensitivity and preference for bitter and sweet tastes in a sample of Malaysian children. A case-control study was conducted among 15 pairs of Malay children aged 7 to 12 years. Seven solutions at different concentrations of 6-n-propylthiouracil and sucrose were prepared for testing bitterness and sweet sensitivity, respectively. The intensity of both bitter and sweet sensitivity was measured using a 100 mm Labelled Magnitude Scale (LMS), while the taste preference was rated using a 5-point Likert scale. The participants were better at identifying bitter than sweet taste (median score 6/7 vs. 4/7). No significant differences were detected for both tastes between normal-weight and overweight groups (bitter: 350 vs. 413, p = 0.273; sweet: 154 vs. 263, p = 0.068), as well as in Likert readings (bitter 9 vs. 8: p = 0.490; sweet 22 vs. 22: p = 0.677). In this sample of Malay children, the participants were more sensitive to bitterness than sweetness, yet presented similar taste sensitivity and preference irrespective of their weight status. Future studies using whole food samples are warranted to better characterize potential taste sensitivity and preference in children.

How Different Snacks Produce a Distinct Effect in Salivary Protein Composition

Saliva secretion changes in response to different stimulation. Studies performed in animals and humans suggest that dietary constituents may influence saliva composition, although the dynamics of these changes, and how they are specific for each type of food, are little known. The objective of the present study was to access the short-term effects of different foods in salivation and salivary protein composition. Twelve participants were tested for four snacks (yoghurt, bread, apple and walnuts). Non-stimulated saliva was collected before and at 0′, 5′ and 30′ after each snack intake. Flow rate, total protein, alpha-amylase enzymatic activity and salivary protein profile were analyzed. Yoghurt and apple were the snacks resulting in higher salivary changes, with higher increases in flow rate and alpha-amylase activity immediately after intake. The expression levels of immunoglobulin chains decreased after the intake of all snacks, whereas cystatins and one pink band (proline-rich proteins—PRPs) increased only after yoghurt intake. Walnut’s snack was the one resulting in lower changes, probably due to lower amounts eaten. Even so, it resulted in the increase in one PRPs band. In conclusion, changes in saliva composition varies with foods, with variable changes in proteins related to oral food processing and perception.

Salivary Protein Profile and Food Intake: A Dietary Pattern Analysis

Saliva research has gained interest due to its potential as a source of biomarkers. One of the factors inducing changes in saliva, in the short term, is food intake, and evidence exist about changes in salivary proteome induced by some food components. Since this topic of research is in its early stages, it was hypothesized that saliva protein composition could be associated with different levels of adherence to dietary patterns that contain higher amounts of plant products. The aim of the present study was to test this hypothesis, in adults, by comparing salivary protein electrophoretic profiles of individuals with different diet characteristics, particularly dietary patterns (DP) that exhibit different proportions of animal and plant-based products. Dietary habits were assessed in 122 adults (61 from each sex, with ages ranging from 20 to 59 years) using Food Frequency Questionnaires. To identify the dietary patterns, a principal component analysis was used. Individual's non-stimulated saliva was evaluated for flow rate, pH, protein concentration, α-amylase activity, and electrophoretic protein profiles. Seven dietary patterns (DP) were identified. Salivary amylase enzymatic activity was positively associated with animal-based and starchy foods DP, and with plant-based fatty foods without wine DP. At the same time, protein bands containing amylase and type S cystatins were positively associated with the cheese/yoghurt and wine DP. Our results support the association of salivary proteomics and different dietary patterns and highlight the need of considering food consumption habits in studies using saliva, since this is a factor associated with variations in the composition of this fluid.

Salivary cystatin SN is a factor predicting iron bioavailability after phytic acid rich meals in female participants

Phytic acid is an inhibitor of iron bioavailability, but it has been suggested that individuals may adapt to phytic acid over time, and that the salivary protein, cystatin SN, may be involved. This study evaluated the relationship between human cystatin SN levels and iron bioavailability after a phytic acid rich meal. Three groups of ten women consumed meals with: (1) 500 mg phytate sprinkles, (2) 500 mg phytate capsules, or (3) no phytic acid. Iron bioavailability was measured by the mealtime percentage of maximum iron recovery; cystatin SN was measured pre-and post-meal by enzyme-linked immunosorbent assay. Pre-to-post meal cystatin SN was positively correlated with improved iron bioavailability in group 1. Pre-to-post meal cystatin SN was correlated with improved iron absorption in groups 1 and 2. Cystatin SN recovery after phytic acid rich meals may be a physiological factor predicting iron bioavailability.

Salivary proteome of a Neotropical primate: potential roles in host defense and oral food perception

BACKGROUND

Saliva contains a very complex mixture of proteins for defense against microbiological pathogens and for oral food perception. Howler monkeys are Neotropical primates that can consume a mostly leaf diet. They are well known to thrive in highly disturbed habitats where they may cope with a diversity of dietary challenges and infection risks. We aimed to describe the salivary proteome of howlers to contribute to better understanding of their physiology.

METHODS

We analyzed the salivary proteins of wild black howler monkeys (Alouatta pigra), by SDS-PAGE-1-D and Nano LC-MS/MS and categorized them by their function involved in host defense and oral food perception.

RESULTS

Our proteomic analysis identified 156 proteins in howler saliva including a number of host defense peptides that are the first line of defense in mammals, such as defensin, cathelicidin, dermcidin, and lactotransferrin, and proteins with anti-bacterial, anti-fungal, and anti-viral capacity, such as IgA, IgG, IgM, BPI, salivary heat shock 70 kDa protein, beta-2-microbulin, and protein S-100. We also identified key proteins necessary for taste perception, including salivary carbonic anhydrase VI, cystatin D, IgA, and fatty acid-binding protein. Proteins to detect astringent foods were identifying, including four members of cystatins (A, B, C and D), lactoperoxidase, and histidine-rich proteins. No chitinase and amylase were identified as would be expected because howlers do not eat insects and little starch. These findings provide basic information to future studies in oral biology, ingestive physiology, and physiological ecology of mammals and non-human primates.

Changes in Salivary Proteome in Response to Bread Odour

It is widely recognized that smelling food results in a mouth-watering feeling and influences appetite. However, besides changes in volume, little is known about the effects that food odours have on the composition of saliva. The aim of the present study was to access the effects that smelling bread has on saliva proteome and to compare such effects with those of chewing and ingesting it. Besides a significant increase in saliva flow rate, together with a decrease in total protein concentration, bread odour induced changes in the proportion of different salivary proteins. The expression levels of two spots of cystatins and two spots of amylase increased due to olfactory stimulation, similar to what happened with bread mastication, suggesting that odour can allow anticipation of the type of food eaten and consequently the physiological oral changes necessary to that ingestion. An interesting finding was that bread odour increased the expression levels of several protein spots of immunoglobulin chains, which were decreased by both bread or rice mastication. This may be of clinical relevance since food olfactory stimulation of salivary immunoglobulins can be used to potentiate the oral immune function of saliva. Moreover, the effects of bread odour in the levels of salivary proteins, previously observed to be involved in oral food processing led to the hypothesis of an influence of this odour in the sensory perception of foods further ingested. Further studies are needed to elucidate this point, as well as whether the changes observed for bread odour are specific, or if different food odours lead to similar salivary proteome responses.

Saliva as a non-invasive tool for assessment of metabolic and inflammatory biomarkers in children

BACKGROUND & AIMS

Epidemiological studies in school-age children are challenging, particularly those that aim to analyse metabolic markers on blood samples obtained via invasive and stressful procedures. The objective of this paper is to evaluate the use of saliva, as a non-invasive tool in epidemiological studies performed in school-age children, to capture metabolic changes associated with body mass index (BMI), dietary characteristics and physical activity in both boys and girls.

METHODS

This is an observational study in which healthy children of ages between 8 and 12 years (n = 129, 60 girls and 69 boys) from three schools in a Mediterranean area of Spain were included. A panel of biomarkers was measured in serum and saliva and correlated with BMI, dietary characteristics and physical activity.

RESULTS

Significant positive correlation between serum and salivary levels were detected for CRP (r = 0.770) in all included children, and boys (r = 0.805) and girls (r = 0.775) separately (P < 0.001, in all cases) and for insulin in girls (r = 0.442; P < 0.05). Among all studied salivary biomarkers, insulin was significantly correlated with the three factors studied: positively with BMI and negatively with dietary characteristics (intake and composition) and physical activity (P < 0.05). Obesity and diet composition were both positively associated to pro-inflammatory biomarkers, CRP and IL1b; while diet composition shared with physical activity levels the correlation with IL6 (positive with energy, fat, carbohydrate and saturated fatty acid intake, and negative with cholesterol intake and average physical activity in boys), NGF and glucose (in both cases correlations were negative with diet composition and physical activity variables) (P < 0.05, in all cases). Sex differences were detected in serum glucose and TNFα.

CONCLUSIONS

Biomarkers in saliva are able to capture differences in BMI, dietary characteristics and physical activity levels in school-age children. Saliva may potentially constitute a useful non-invasive and stress-free tool to evaluate metabolic markers of inflammation and/or metabolism related to BMI and lifestyle in a sex-dependent manner.