Effect of a long-term change from a mixed to a lactovegetarian diet on human saliva

Influence of the vegan, vegetarian and omnivore diet on the oral health status in adults: a systematic review and meta-analysis

OBJECTIVE

This systematic review aimed to evaluate the influence of the nature of diet (vegan, vegetarian, and omnivore) on the oral health status in adults.

METHODS

This systematic review and meta-analysis was performed using the PRISMA guidelines. Electronic databases [PubMed, Embase, CENTRAL], online search engines (Google Scholar), research portals, and hand searches were performed systematically to identify studies. The last literature search was performed February 1st, 2021. Studies were included if they reported on the influence of the nature of diet on the oral health status (oral hygiene, periodontal health, dental status, and salivary function) in adults, by two investigators. Inter-investigator reliability was evaluated using Kappa (κ) statistics. PROSPERO registration number: CRD42020211567.

RESULTS

Twenty-two studies were included for data extraction and final analysis. The meta-analysis revealed that the bleeding on probing measure was higher in omnivores (Z = -4.057, p < 0.0001; 95% CI: -0.684, -0.238; I² = 0.0%) and the overall periodontal health was significantly better in vegan/vegetarians than omnivores (Z = -2.632, p = 0.008; 95% CI: -0.274, -0.073; I² = 29.7%). Vegan/vegetarians demonstrated more dental erosion (Z = 3.325, p = 0.001; 95% CI: 0.170, 0.659; I² = 0.0%). In adults over 60 years old, the prevalence of caries was higher in omnivores (Z = 3.244, p = 0.001; 95% CI: 0.092, 0.371; I² = 0.0%), while complete edentulism was more prevalent in vegetarians (Z = -4.147, p < 0.0001; 95% CI: -0.550, -0.197; I² = 0.0%).

CONCLUSIONS

This review reveals that adults on an omnivore diet may be associated with a higher risk for periodontal problems and dental caries, while vegetarians/vegans may be associated with a higher risk for dental erosion.

Ethnicity, gender and physiological parameters: Their effect on in vivo flavour release and perception during chewing gum consumption

In this study, the impact of physiological parameters, ethnicity and gender on flavour perception and flavour release of chewing gum was investigated. Proton Transfer Reaction Mass Spectrometry in-nose monitoring of volatile organic compounds was coupled to discontinuous time intensity sensory evaluation for mint flavour and sweetness perception. Each of the 29 subjects, 14 European and 15 Chinese panelists (13 male and 16 females, age 24 ± 1.4 years old) consumed the samples in triplicates. Physiological parameters (oral cavity volume, salivary flow, acetone and isoprene concentration and fungiform papillae density) were measured. Significant differences for in vivo flavour release between Chinese and European panelists after 90 s of consumption and after the gum was removed from the mouth were found. Significant differences were observed also in flavour and sweetness perception while no gender effect was detected. In this work, for the first time an effect of ethnicity on in-nose flavour release monitored through PTR-MS was noticed during chewing gum consumption, in agreement with the findings from sensory evaluation. Single physiological parameters do not explain the relation between flavour in nose release and perception during consumption.

Protein expression in submandibular glands of young rats is modified by a high-fat/high-sugar maternal diet

OBJECTIVE

Maternal diet has consequences on many organs of the offspring, but salivary glands have received little attention despite the importance of the saliva secretory function in oral health and control of food intake. The objective of this work was therefore to document in rats the impact of maternal high-fat/high-sugar diet (Western Diet) on submandibular glands of the progeny.

DESIGN

Sprague-Dawley rat dams were fed either a Western diet or control diet during gestation and lactation and their pups were sacrificed 25 days after birth. The pups' submandibular gland protein content was characterized by means of 2D-electrophoresis followed by LC-MS/MS. Data were further analyzed by Gene Ontology enrichment analysis and protein-protein interactions mapping. The expression of two specific proteins was also evaluated using immunohistochemistry.

RESULTS

Combining both male and female pups (n = 18), proteome analysis revealed that proteins involved in protein quality control (e.g. heat shock proteins, proteasome sub-units) and microtubule proteins were over-expressed in Western diet conditions, which may translate intense metabolic activity. A cluster of proteins controlling oxidative stress (e.g. Glutathione peroxidases, peroxiredoxin) and enhancement of the antioxidant activity molecular function were also characteristic of maternal Western diet as well as under-expression of annexin A5. The down-regulating effect of maternal Western diet on Annexin A5 expression was significant only for males (p < 0.05).

CONCLUSIONS

A maternal Western diet modifies the protein composition of the offspring's salivary glands, which may have consequences on the salivary function.

Oral Candidal Carriage in Subjects with Pure Vegetarian and Mixed Dietary Habits

INTRODUCTION

Candida albicans being a part of the normal oral microbial flora is one of the most commonly isolated species from the oral cavity. Recent studies have shown a steady rise in the number of non C. albicans species, which are relatively resistant to common antifungal agents and are being recognized as potential pathogens. It is vital to ascertain the predisposing factors leading to such a shift in the oral candidal flora.

AIM

To estimate the prevalence of candidal species among vegetarians and non-vegetarians.

MATERIALS AND METHODS

Clinical data including age, gender, and diet preference of 238 participants were noted. Participants with a history of systemic disorders, oral prosthesis, salivary gland disorders and habits such as smoking, alcoholism, and tobacco usage were excluded from the study. The participants were asked to gargle a 10 ml solution of phosphate buffered saline for one minute before depositing the same in a sterile container. The samples were cultured using Hicrome agar media. Data analysis was carried out using Statistical Package for Social Sciences (SPSS software) version 10.5 and differences between individual groups were tested by Chi-square test.

RESULTS

Among 238 samples, 127 (53.3%) samples were positive for Candida. The candidal prevalence in vegetarians (68.5%) was higher than non-vegetarians (40.7%). C. albicans was the most common species to be isolated in both vegetarians (35.1%) and non-vegetarians (39.2%). Candida glabrata and Candida tropicalis showed a higher prevalence in vegetarians (30.5% and 10.1%, respectively) in comparison to non-vegetarians (8.4% and 2.3%, respectively). Candida krusei was isolated only from vegetarians (4.6%).

CONCLUSION

Results indicate that diet plays a major role in oral candidal prevalence and species specificity which in turn may predispose the vegetarians toward these pathogenic organisms.

Associations between food consumption patterns and saliva composition: Specificities of eating difficulties children

Identifying objective markers of diet would be beneficial to research fields such as nutritional epidemiology. As a preliminary study on the validity of using saliva for this purpose, and in order to explore the relationship between saliva and diet, we focused on clearly contrasted groups of children: children with eating difficulties (ED) receiving at least 50% of their energy intake through artificial nutrition vs healthy controls (C). Saliva of ED and C children was analyzed by various methods (targeted biochemical analyses, 2-D electrophoresis coupled to MS, ¹H NMR) and their diet was characterized using food frequency questionnaires, considering 148 food items grouped into 13 categories. Complete datasets were obtained for 16 ED and 16 C subjects (median age 4.7y and 5.0y, respectively) and the statistical link between salivary and dietary characteristics was studied by Multiple Factor Analysis (MFA). Overall, ED children showed as expected lower consumption frequency scores and higher food selectivity. The two groups of children differed in "diet/saliva" associations. Some distinctive salivary variables were common to both groups of children. For example, carbonic anhydrase 6 and the consumption frequency of biscuits & sweets and drinks were positively associated with the MFA axis 1 in C children, but oppositely associated in ED children. Specifically for ED children, abundant salivary proteins (cystatins, amylase, amylase fragments) and some metabolites (amino acids, galactose, lactate) correlated with axis 1, together with the consumption frequency of sauces & seasonings, bread & cereal products, ready-to-eat meals, fish, biscuits & sweets, drinks and potatoes. Specifically for C children, several proteins (serum albumin, haptoglobin, Igκ, apolipoprotein A-1, α-1 antitrypsin) correlated with axis 1, together with the consumption frequency of biscuits & sweets, milk & dairy products, drinks, fruit, meat and vegetables. This study demonstrates that the qualitative aspect of diet is linked to saliva composition, and that the associations between dietary consumption and salivary composition differ between groups of subjects with contrasted diets.

Salivary Composition Is Associated with Liking and Usual Nutrient Intake

Salivary flow and composition have an impact on flavor perception. However, very few studies have explored the relationship between saliva, individual liking and usual dietary intake. The aim of our study was to evaluate the association of salivary flow and composition with both a liking for fat, saltiness and sweetness and the usual nutrient intake in an adult French population. Liking for fat, saltiness, and sweetness were inferred from liking scores obtained during hedonic tests on 32 food products among 282 French adults participating in the Nutrinet-Santé Study. Before assessing liking, resting saliva was collected. Standard biochemical analyses were performed to assess specific component concentrations and enzymatic activities. Dietary data were collected using three web-based 24h records. Relationships between salivary flow and composition, sensory liking and nutrient intake were assessed using linear regression. Total antioxidant capacity was positively associated with simple carbohydrate intake (β = 31.3, 95% CI = 1.58; 60.99) and inversely related to complex carbohydrate consumption (β = -52.4, 95% CI = -87.51; -19.71). Amylolysis was positively associated with both total (β = 0.20, 95% CI = 0.01; 0.38) and simple carbohydrate intake (β = 0.21, 95% CI = 0.01; 0.39). Salivary flow was positively associated with liking for fat (β = 0.14, 95% CI = 0.03; 0.25). Proteolysis was positively associated with liking for saltiness and for fat (β = 0.31, 95% CI = 0.02; 0.59; β = 0.28, 95% CI = 0.01; 0.56, respectively). Amylolysis was inversely associated with liking for sweetness (β = -10.13, 95% CI = -19.51; -0.75). Carbonic anhydrase 6 was inversely associated with liking for saltiness (β = -46.77, 95% CI = -86.24; -7.30). Saliva does not substantially vary according to a usual diet, except for carbohydrate intake, whereas the specific association between salivary flow/composition and sensory liking suggests the influence of saliva characteristics in food acceptance.

Controversies in fat perception

Nutritional fat is one of the most controversial topics in nutritional research, particularly against the background of obesity. Studies investigating fat taste perception have revealed several associations with sensory, genetic, and personal factors (e.g. BMI). However, neuronal activation patterns, which are known to be highly sensitive to different tastes as well as to BMI differences, have not yet been included in the scheme of fat taste perception. We will therefore provide a comprehensive survey of the sensory, genetic, and personal factors associated with fat taste perception and highlight the benefits of applying neuroimaging research. We will also give a critical overview of studies investigating sensory fat perception and the challenges resulting from multifaceted methodological approaches. In conclusion, we will discuss a multifactorial approach to fat perception to gain a better understanding of the underlying mechanisms that cause varying fat sensitivity which could be responsible for overeating. Such knowledge might be beneficial in new treatment strategies for obesity and overweight.

Induction of salivary proteins modifies measures of both orosensory and postingestive feedback during exposure to a tannic acid diet

There are hundreds of proteins in saliva. Although it has long been hypothesized that these proteins modulate taste by interacting with taste receptors or taste stimuli, the functional impact of these proteins on feeding remains relatively unexplored. We have developed a new technique for saliva collection that does not interfere with daily behavioral testing and allows us to explore the relationship between feeding behavior and salivary protein expression. First, we monitored the alterations in salivary protein expression while simultaneously monitoring the animals' feeding behavior and meal patterns on a custom control diet or on the same diet mixed with 3% tannic acid. We demonstrated that six protein bands increased in density with dietary tannic acid exposure. Several of these bands were significantly correlated with behaviors thought to represent both orosensory and postingestive signaling. In a follow-up experiment, unconditioned licking to 0.01–3% tannic acid solutions was measured during a brief-access taste test before and after exposure to the tannic acid diet. In this experiment, rats with salivary proteins upregulated found the tannin solution less aversive (i.e., licked more) than those in the control condition. These data suggest a role for salivary proteins in mediating changes in both orosensory and postingestive feedback.

The effect of dietary intervention on paraffin-stimulated saliva and dental health of children participating in a randomized controlled trial

OBJECTIVES

The aim was to study the impact of dietary intervention on the properties of paraffin-stimulated saliva, and on dental caries.

STUDY DESIGN

At 7 months of age 1062 infants (540 intervention; 522 controls) started in the prospective, randomized Special Turku Intervention Project (STRIP) aimed at restricting the child's saturated fat and cholesterol intake to prevent atherosclerosis of adult age (www.clinicaltrials.gov NCT 00223600). At 3 years of age, every fifth child was invited to an oral sub-study, and 148 (78 boys) children attended. At 6, 9, 12 and 16 years of age 135, 127, 114 and 88 children were restudied, respectively. Dietary intakes of carbohydrates, protein, saturated fat, calcium, phosphate, and fibre were regularly recorded using 4-day food records. Height and weight were regularly monitored. Paraffin-stimulated saliva samples were collected at 6, 9, 12 and 16 years of age, and analyzed for flow rate, buffer capacity, calcium, phosphate and proteins. Dental health was recorded and expressed as d3mft/D3MFT, and as time of caries onset.

RESULTS

Dietary intakes of calcium, phosphate and fibre, and salivary flow rate increased with time in both groups (p<0.001, GLM for repeated measures). Fibre intake and salivary flow rate were higher in the intervention than in the control group (p=0.042 and p=0.0394, respectively, GLM for repeated measures). There were no correlations between dietary intakes and salivary concentrations of calcium or phosphate. Children who did not have caries experience (d3mft/D3MFT=0) during the entire follow-up had higher salivary calcium than those who had caries already at 3 years of age. The association between salivary calcium and caries onset was significant up to 12 years of age. Toothbrushing frequency was statistically significantly associated with caries-onset at ages 6 (gamma statistic 0.457, p=0.046) and 12 years (gamma statistic 0.473, p=0.019).

CONCLUSIONS

The current long-term dietary intervention increased children's paraffin-stimulated salivary flow rate. The concentration of salivary calcium was directly correlated to dental health. Higher salivary flow rate in the intervention group is believed to be due to higher fibre intake in the intervention group.

Semantic conditioning of salivary pH for communication

OBJECTIVES

Semantic conditioning of salivary pH was investigated as a new paradigm for binary communication.

METHODS AND MATERIALS

In a sample of eleven healthy participants, affirmation or negation of presented statements were paired with milk and lemon to condition changes in salivary pH level.

RESULTS

Significant differences between the conditioned reactions were found at the group level. However, the analysis of pH changes on single-subject level revealed significant differences between affirmative and negative responses to the presented statements only for isolated samples in few participants. When classifying a change in pH value of more than .01 as correct response to a statement, only responses to affirmative statements reached mean accuracies of more than 60%.

CONCLUSION

Improvements in the paradigm are necessary before testing it with the critical target population of patients to prove its profit for basic yes/no communication in case no other reliable means of communication could be preserved.

Lifestyle, mental health status and salivary secretion rates

The relations between salivary variables, lifestyle and mental health status were investigated for 61 healthy female university students. The salivary secretion rates were significantly higher in the good lifestyle groups compared with the poor lifestyle groups. Among the 8 lifestyle items tested. "eating breakfast" and "mental stress" were significantly related to the salivary secretion rates. The present findings suggest that the acquisition of a good lifestyle is also very important from the viewpoint of the prevention of oral disease.A highly significant correlation (r=0.97; p<0.01) between the salivary cortisol levels and the cortisol secretion rates when controlled for the salivary secretion rates was also observed. This suggests that there is a high correlation between the intact salivary cortisol levels and the total cortisol quantity per unit time. Therefore, both these values can be used as a good index for the salivary cortisol determination.

Determinants of salivary alpha-amylase in humans and methodological considerations

Salivary alpha-amylase (sAA) has been proposed as a marker for activity of the sympathetic nervous system (SNS). Recent studies in support of this hypothesis have led to an increased number of researchers integrating amylase measurements into their study designs. Salivary alpha-amylase is produced locally in the salivary glands, controlled by the autonomic nervous system. This entails some methodological consequences and potential pitfalls that might lead to increased error variance and thus prevent successful testing of hypotheses. The goal of this review is to summarize basic and recent findings on methodological issues and potential factors influencing sAA measurement, and to derive a set of recommendations enabling researchers to successfully using sAA in psychoneuroendocrinological experiments.

Stimulated salivary flow rate and buffer effect in schoolchildren from Greenland and Sweden: a comparative study

OBJECTIVE

To compare food habits and stimulated salivary flow rate and buffer effect between schoolchildren from Greenland and Sweden and to evaluate whether the change in lifestyle concerning eating habits in Sweden during recent decades has resulted in any obvious alteration in these salivary properties.

MATERIAL AND METHODS

Fifty healthy schoolchildren from Greenland were included and compared with 50 age-matched and gender-matched Swedish children. Whole saliva stimulated by chewing was collected, and prior to sampling each participant filled in a simple questionnaire regarding their food habits.

RESULTS

Salivary flow rate and buffer effect were significantly (p<0.001) higher for the Greenlandic children. The difference in flow rate was on average 0.71 ml/min. Milk, fish/meat and fruit/vegetables were more frequently consumed by the Swedish children, while snacks, soft drinks and sweets had a higher consumption frequency on Greenland. No obvious correlation could be found between consumption frequency of the tested food products and flow rate or buffer effect of saliva. Twenty-nine Swedish children were within the age range+/-6 months of an age with earlier documented values of stimulated salivary flow rate. Twenty-six of these 29 Swedish children were within the 25-75 percentile range of the old values, while 22 of their Greenlandic "twins" were in or above percentile 75.

CONCLUSIONS

Obvious differences in salivary flow rate and buffer effect between schoolchildren from Greenland and Sweden illustrated the importance of being cautious when exchanging reference data between different cultures/ethnic groups.

High oral prevalence of Candida krusei in leprosy patients in northern Thailand

Although Candida albicans is the most common human yeast pathogen, other Candida species such as C. krusei are now recognized as emerging agents, especially in patients with human immunodeficiency virus (HIV) disease. C. krusei is inherently resistant to the widely used triazole antifungal fluconazole and poses therapeutic problems, especially in systemic candidiasis. In a surveillance study of leprosy patients (with arrested or burnt-out disease) in a leprosarium in northern Thailand, we found a rate of oral carriage of C. krusei (36%) significantly (P < 0.05) higher than that for a healthy control group (10%). Among the Candida-positive patients, 16 of 35 (46%) carried C. krusei, while C. albicans was the second most common isolate (12 of 35 patients; 34%). The corresponding figures for the control group were 2 of 13 (15%) and 6 of 13 (46%), respectively. Studies of the antifungal resistance of the C. krusei isolates from patients indicated that all except one of the isolates were resistant to fluconazole, two isolates were resistant to ketoconazole, and all isolates were sensitive to amphotericin B. Evaluation of their genetic profiles by randomly amplified polymorphic DNA analysis with three different primers and subsequent analysis of the gel profiles by computerized cluster-derived dendrograms revealed that the C. krusei isolates from patients belonged to 10 disparate clusters, despite the origin from a single locale. These nascent findings indicate an alarmingly high prevalence of a Candida species resistant to a widely used antifungal in a part of the world where HIV disease is endemic.

A further note on the sampling device for the anti-mutagenicity of saliva

OBJECTIVES

The purpose of this study was to compare the anti-mutagenicity of Salivette and test-tube sampling saliva. In addition, the relation between the inhibiting and pH-buffering capacities of saliva was investigated.

METHODS

Subjects were 52 healthy female university students. The collection of saliva samples was carried out using 2 sampling devices; test-tube and Salivette. The anti-mutegenicity of the saliva was measured using the umu test.

RESULTS

The inhibiting capacity of Salivette-saliva was significantly lower compared with that of testube-saliva (p<0.01,t test). However, there was a significant correlation between them (r=0.35; p<0.05). In addition, there was a significant correlation between the inhibiting and pH-buffering capacities of saliva (r=-0.36; p<0.05).

CONCLUSIONS

These findings suggest that both the Salivette and the test-tube may be appropriate as saliva-sampling devices. In addition, they suggest that the bicarbonates might inhibit the anti-mutagenicity of saliva, or that the activity of substances related to the anti-mutagenicity of saliva might be dependent on pH.

The oral prevalence of aerobic and facultatively anaerobic gram-negative rods and yeasts in semi-recluse human vegetarians

Limited data exist on the oral ecology of vegetarians. Hence the dental and periodontal status, and the oral prevalence of aerobic and facultatively anaerobic Gram-negative rods (AGNR) and yeasts, were studied in 36 semi-recluse, vegetarian, Buddhist monks and nuns in Hong Kong. The oral prevalence of AGNR and yeasts was 61.1% and 33.3%. There was no correlation between the prevalence of AGNR and/or yeasts and the incidence of carious or filled teeth and the health status of the periodontium. Rather, the results of this study combined with those of previous studies suggest that increasing age and the consumption of food prepared in communal kitchens might be more important contributory factors in the oral prevalence of AGNR than the nature of the diet itself or the health of the dentition and periodontium.

Comparison of some salivary variables between vegetarians and omnivores

The aim of the study was to compare salivary variables in a group of vegetarians with a group of omnivores. Twenty-nine vegetarians, 19 women and 10 men, mean age 35 yr, and 28 omnivores, 20 women and 8 men, mean age 35 yr, were compared in terms of salivary secretion rate, pH, buffer capacity, mutans streptococci and lactobacilli. The vegetarians had a significantly higher secretion rate, but there were no other significant differences regarding the salivary variables. The difference in secretion rate may have been caused by some lifestyle factor(s) differing between vegetarians and omnivores which probably mainly include nutrient(s), texture and roughness of the food.