Salt-Taste Polymorphism TRPV1-rs8065080 Is Associated with Increased Likelihood of Depression in an Elderly Cohort.

INTRODUCTION: Despite the prevalence of depression and anxiety worldwide, their aetiologies remain unclear, and they can be difficult to diagnose and treat. Changes in salt-taste perception have been found in both conditions. Single-nucleotide polymorphisms (SNPs) in the salt-taste-related gene, TRPV1, have been associated with alterations to salt-taste perception, preference, and sodium consumption. Diet quality is a known modifier of depression and anxiety and recently, sodium intake has been studied in mental health. However, the relationships between salt-taste genetics, depression, anxiety, and these dietary factors are yet to be elucidated. METHODS: Data from the well-characterized cross-sectional Retirement Health and Lifestyle Study (n = 536, ≥65 y) were used to explore the relationships between the salt-taste SNP TRPV1-rs8065080, levels of depression and anxiety (Hospital Anxiety and Depression Scale, HADS), estimated sodium intake, and diet quality in this secondary analysis. Standard least-squares regression and nominal logistic regression modelling were used to compare continuous and categorical variables, respectively, with analyses stratified by sex. RESULTS: Presence of the TRPV1-rs8065080 variant allele (C) was found to increase the likelihood of having depression (HADS) in the total population and in males. The associations remained significant after adjusting for sodium intake, three diet quality indices, and demographic variables, suggesting that TRPV1-rs8065080 genotype is driving the association with depression. DISCUSSION/CONCLUSION: Future studies should explore extra-oral functions of the SNP and salt-taste receptors in the brain and the roles of neurotransmitters common to both depression and salt taste to improve the management of this increasingly prevalent and difficult-to-treat condition.

Liking of salt is associated with depression, anxiety, and stress.

Early research has shown variations in salt taste qualities in depression, anxiety, and stress. These studies evaluated changes to salt taste intensity and liking (pleasantness) of salt solutions but not of salty foods. Therefore, an Australian population survey (n = 424) was conducted where participants rated recalled intensity and liking of salt index foods and completed the Depression, Anxiety, and Stress Scale (DASS-21) to measure these states. Standard least squares regression (post hoc Tukey's HSD) compared means between groups, and nominal logistic regression assessed differences in distributions between categories. Higher salt liking was found in participants with DASS-21 scores indicative of severe depression (68.3 vs. 60.0, P = 0.005) and severe anxiety (68.4 vs. 60.0, P = 0.001) in comparison to those with normal scores, in all models. Higher salt liking was found in participants with DASS-21 scores indicative of moderate stress (67.7 vs. 60.2, P = 0.009) in the unadjusted model only. Higher salt liking was found in females with DASS-21 scores indicative of anxiety and stress, and in males with indicative depression and anxiety. No relationships between salt taste intensity ratings and the mood states were found. Results indicate that liking salty foods is positively correlated with depression, anxiety, and stress scores. Further research on the relationships between salt liking and intake of salt and salty foods, and the biological mechanisms of these mood states are needed to direct the application of findings toward potential new risk assessment measures, dietary interventions, or therapeutics.

Sour Taste SNP KCNJ2-rs236514 and Differences in Nutrient Intakes and Metabolic Health Markers in the Elderly.

Single nucleotide polymorphisms (SNPs) in taste receptors influence dietary choices that contribute to health and quality of life. Individual differences in sour taste perception and preference have been linked to heritable genetics, yet the impact of sour taste receptor SNPs on sour taste is under-researched, and studies on sour taste SNP associations to diet and health are lacking. Therefore, this study explored the relationships between the sour taste SNP KCNJ2-rs236514 and estimated macronutrient, vitamin and mineral intakes, and markers of metabolic health. Associations were explored in 523 participants aged 65 years and older with data analysed using standard least squares and nominal logistic regression modelling with post hoc student's t-tests and Tukey's HSD. Associations were found between the presence of the KCNJ2-rs236514 variant allele (A) and lower intakes of energy, total fat, monounsaturated fat and saturated fat. The lower fat intakes were significant in female carriers of the variant allele (A), along with lower water intake. Lower retinol, riboflavin, folate, calcium and sodium intakes were found in the KCNJ2-A allele carriers. In females, the variant allele was associated with lower sodium intake before and after Bonferroni adjustment. Higher body mass index, waist and waist-to-hip ratio measures were found in males carrying the variant allele. Lower levels of liver function biomarkers were associated with the presence of the KCNJ2-A allele. Overall and in males, the variant's association to lower gamma-glutamyl transferase (GGT) levels remained significant after Bonferroni adjustments. These novel findings suggest the sour taste SNP, KCNJ2-rs236514, may be modifying macronutrient, vitamin and mineral intakes, and markers of metabolic health. Research on the extra-oral functions of this SNP may improve health outcomes for those with overweight, obesity and liver disease.

Association between Sour Taste SNP KCNJ2-rs236514, Diet Quality and Mild Cognitive Impairment in an Elderly Cohort.

Differences in sour-taste thresholds have been identified in cognition-related diseases. Diet is a modulator of cognitive health, and taste perception influences dietary preferences and habits. Heritable genetics and polymorphisms in the KCNJ2 gene involved in the transduction of sour taste have been linked to variations in sour taste and non-gustatory functions. However, relationships between sour taste genetics, mild cognitive impairment, and diet quality are yet to be elucidated. This study investigated the associations between the presence of the KCNJ2-rs236514 variant (A) allele, diet quality indices, and mild cognitive impairment evaluated by the Mini-Mental State Examination (MMSE), in a secondary cross-sectional analysis of data from the Retirement Health & Lifestyle Study. Data from 524 elderly Australians (≥65y) were analyzed, using standard least squares regression and nominal logistic regression modeling, with demographic adjustments applied. Results showed that the presence of the KCNJ2-A allele is associated with increased proportions of participants scoring in the range indicative of mild or more severe cognitive impairment (MMSE score of ≤26) in the total cohort, and males. These associations remained statistically significant after adjusting for age, sex, and diet quality indices. The absence of association between the KCNJ2-A allele and cognitive impairment in women may be related to their higher diet quality scores in all indices. The potential link between sour taste genotype and cognitive impairment scores may be due to both oral and extra-oral functions of sour taste receptors. Further studies are required on the role and relationship of neurotransmitters, sour taste genotypes and sour taste receptors in the brain, and dietary implications, to identify potential risk groups or avenues for therapeutic or prophylactic interventions.

Salt Taste Genotype, Dietary Habits and Biomarkers of Health: No Associations in an Elderly Cohort.

A small amount of emerging research has observed variations between individual sensitivity, preference and intake of salt in the presence of single nucleotide polymorphisms (SNP) on the genes encoding salt taste receptors. Sodium intake is a significant risk factor for common diseases in elderly populations such as hypertension and cardiovascular disease; however, this does not fully explain the risk. Research into the influence of salt taste genetics on diet quality is yet to be undertaken and current research on indicators of health is limited and mixed in the direction of associations. Therefore, a secondary analysis of data from a well-characterised elderly cohort (the cross-sectional Retirement Health and Lifestyle Study, n = 536) was conducted to explore relationships between the salt taste-related SNP TRPV1-rs8065080 (assessed by Taqman genotyping assay), dietary habits and biomarkers of health. Data were analysed with standard least squares regression modelling and Tukey's HSD post hoc tests. No association was found between the TRPV1-rs8065080 genotype, sodium intake or multiple diet quality indices (assessed by food frequency questionnaire). Sodium-related markers of health including blood pressure and markers of kidney function (urinary creatinine and albumin/creatinine ratio) and general health markers, such as Body Mass Index (BMI), were also not related to TRPV1-rs8065080 genotype. To date, this study is the most comprehensive investigation conducted to determine if the TRPV1-rs8065080 genotype relates to sodium intake and health markers influenced by sodium intake. Although no significant relationships were found, these findings are an important contribution to the limited body of knowledge surround this SNP. In addition to further research across other ages and cultures, the TRPV1-rs8065080 genotype may interact with other ion channels, and so further studies are required to determine if polymorphic variations influence sodium intake, diet and health.