Association between body mass index and salivary uric acid among Mexican-origin infants, youth and adults: Gender and developmental differences

Phosphorus modifies the association between body mass index and uric acid: Results from NHANES 2007-2018

INTRODUCTION

Studies in recent years have shown that high uric acid causes harm to the human body, which has become a serious public health problem. Elevated serum uric acid has been shown to be associated with obesity, but the relationship between BMI and uric acid (UA) remains controversial. Although the association between BMI and UA has been well studied, the effect of phosphorus levels in vivo on this association remains unclear. This study aimed to determine the relationship between BMI and serum uric acid and the effect of phosphorus on the relationship between the two.

RESEARCH DESIGN AND METHODS

The present study analyzed data from the National Health and Nutrition Examination Survey (NHANES) continuous 2007-2018 cycle. We included 10786 participants aged 20 years and over. Multivariable linear regression was performed to assess the association between BMI and serum uric acid. phosphorus was stratified into low phosphorus (<3.3 mg/dl), middle phosphorus (3.3-3.9 mg/dl) and high phosphorus (>3.9 mg/dl). Correction of the effect of phosphorus was assessed by testing the interaction between BMI and UA in multivariate linear regression.

RESULTS

In this cross-sectional study, we found that BMI was positively associated with UA in the female population but not significantly in the male population or in the total population. In multiple regression analysis, UA was 0.51 higher in the highest female BMI group than in the lowest group (p = 0.0001). The relationship between BMI and UA differed significantly by gender under the influence of phosphorus, with men and women in Model II having a greater elevation of UA in men than in women within most groups. (BMI >30, phosphorus >3.9 mg/dl, β:0.83 95% CI: 0.43, 1.23 vs β: 0.79 95% CI: 0.30, 1.29). In addition, phosphorus significantly altered the positive association between BMI and UA in most models.

CONCLUSION

Our results indicate significant associations between BMI and uric acid in women, with higher BMI values likely to be associated with a higher risk of hyperuricemia, suggesting that uric acid levels in obese people should be closely monitored in clinical practice. Phosphorus and BMI have an interactive effect in elevating UA and should be noted as indicators of phosphorus in clinical practice.

Distinguishable short-term effects of tea and water drinking on human saliva redox

Food consumption can alter the biochemistry and redox status of human saliva, and the serving temperature of food may also play a role. The study aimed to explore the immediate (3 min) and delayed (30 min) effects of hot tea (57 ± 0.5 °C) ingestion and cold tea (8 ± 0.5 °C) ingestion on the salivary flow rate and salivary redox-relevant attributes. The saliva was collected from 20 healthy adults before, 3-min after and 30-min after the tea ingestion. The hot or cold deionised water at the same temperatures were used as control. The salivary flow rate and redox markers in hot tea (HBT), cold tea (CBT), hot water (HW) and cold water (CW) group were analysed and compared. The results demonstrated that neither the black tea nor the water altered the salivary flow rate; the black tea immediately increased the salivary thiol (SH) and malondialdehyde (MDA) content while reduced salivary uric acid (UA) significantly. The tea ingestion showed a tendency to elevate the ferric reducing antioxidant power (FRAP) in saliva, although not significantly. The water ingestion decreased the MDA content immediately and increased the UA level significantly. Cold water was found to induce a greater delayed increase in total salivary total protein (TPC) than the hot water. In conclusion, the black tea ingestion affects the redox attributes of human saliva acutely and significantly, while the temperature of drink makes the secondary contribution.

Nonlinear relationship between body mass index and serum uric acid: An observational and Mendelian randomization study among Chinese adults

BACKGROUND AND AIMS

Conflicting evidence exists on the relationship between body mass index (BMI) and serum uric acid (SUA), and importantly, the causal role of BMI in SUA remains unclear. We aimed to evaluate the BMI-SUA relationship and its causality among Chinese adults using observational and Mendelian randomization (MR) analyses.

METHODS AND RESULTS

Study included 6641 adults from East China. A genetic risk score based on 14 BMI-associated East Asian variants was formulated. One-sample MR and non-linear MR analyses assessed the causal link between BMI_GRS and SUA levels. Mean BMI levels were 24.8 (SD 3.4) and 24.3 (SD 3.6) kg/m2 in men and women, respectively. Spline models revealed gender-specific BMI-SUA associations: a reverse J-shape for men and a J-shape for women (P-values for nonlinearity <0.05). In men, BMI showed a positive correlation with SUA levels when BMI was below 29.6 kg/m2 (beta coefficient 19.1 [95 % CI 15.1, 23.0] μmol/L per 1-SD increase in BMI), while in women, BMI exhibited a negative correlation with SUA levels when the BMI was less than 21.7 kg/m2 (beta coefficient -12.9 [95 % CI -21.6, -4.1] μmol/L) and a positive correlation when BMI exceeded 21.7 kg/m2 (beta coefficient 13.3 [95 % CI 10.9, 15.8] μmol/L). Furthermore, MR analysis suggested non-linear BMI-SUA link in women but not men.

CONCLUSION

Our study indicates a non-linear correlation between BMI and SUA in both genders. It is noteworthy that in women, this correlation may have a causal nature. Nevertheless, further longitudinal investigations are required to authenticate our findings.

Association between biomarkers of redox status and cytokines with different patterns of habitual physical activity in eutrophic and overweight/obese preschoolers: multivariate analysis of a cross-sectional study

BACKGROUND

Although it is well known that obesity is frequently associated with reduced levels of habitual physical activity (HPA), which contributes to determining severe oxidative stress and inflammatory state, this association is however unknown in preschoolers so far. This study aimed to investigate the association between biomarkers of redox status and cytokines with different patterns of HPA according to the adiposity of preschoolers.

METHODS

A cross-sectional study was conducted in 50 preschoolers (25 overweight/obese, OW/OB and 25 eutrophic, EU), matched for age, sex, economic level, and maternal education. Total antioxidant capacity (TAC), superoxide dismutase (SOD) and catalase (CAT) activities, substances reactive to thiobarbituric acid (TBARS), soluble tumor necrosis factor receptors (sTNFRs), and leptin levels were evaluated. HPA levels were evaluated by accelerometry (ActiGraph GT9X accelerometer). Correlation, multiple linear regression, and partial least squares regression analysis were used to determine the association between redox status biomarkers and cytokines with different patterns of HPA (HPA level, bouts of moderate to vigorous physical activity [MVPA], and multivariate pattern of HPA) in EU and OW/OB preschoolers.

RESULTS

OW/OB preschoolers had lower CAT activity, higher levels of TAC, TBARS, and cytokines, and similar levels of HPA to EU preschoolers. In EU preschoolers, SOD activity exhibited a stronger negative association with moderate intensity ranges of HPA (R2 = 0.18), and negative correlation with sTNFRs (r = -0.40 to -0.46). TBARS had a stronger positive association with ranges of light intensity in the multivariate pattern of HPA (R2 = 0.10). In OW/OB preschoolers, the HPA multivariate associative pattern was predominantly from vigorous intensity ranges. Thus, SOD activity had a positive association with the multivariate pattern of HPA (R2 = 0.38) and MVPA bouts (β [95% CI] = 0.457 [0.0026. 0.0576]). TAC had a negative association with the multivariate pattern of HPA (R2 = 0.38) and MVPA bouts (β [95% CI] = -0.718 [-0.0025. -0.0003]). Additionally, leptin levels were lower in OW/OB preschoolers engaged in vigorous physical activity (VPA) (8000-9999 counts/min) for longer periods of time.

CONCLUSION

The results of this study indicate that OW/OB preschoolers have higher levels of oxidative stress biomarkers and pro-inflammatory cytokines compared to EU preschoolers. Moreover, VPA may exert antioxidative and anti-inflammatory effects in OW/OB preschoolers.

Differences in maternal and neonatal cardiometabolic markers and placenta status by foetal sex. The GESTAFIT project

Aims:

To explore the differences in some maternal-neonatal metabolic markers and placenta status by foetal sex.

Methods:

One hundred thirty-nine Caucasian pregnant women from the GESTAFIT project and their new-borns were included in the present cross-sectional study. Serum cardiometabolic markers (i.e. lipid and glycaemic profile and uric acid) were analysed at late pregnancy and at birth. In placenta, telomeres length, proportion of deleted mitochondrial-DNA and mitochondrial-DNA density, some minerals and interleukin 8, epidermal growth factor, fibroblast growth factor-2 and vascular endothelial growth factor were measured. The study was run between November 2015 and April 2018.

Results:

Mothers carrying a male showed higher serum triglycerides than mothers carrying a female at late pregnancy (p < .05). Serum total and low-density lipoprotein cholesterol were greater in males’ umbilical cord blood artery compared to females’ new-borns (both, p < .05). Mothers of males and male new-borns presented higher uric acid than mothers of females and female new-borns at birth (p < .05). Female’s placentas presented greater placental-newborn weight ratio, manganese content and fibroblast growth factor-2 (all, p ⩽ .05), and evidence of statistical significance in telomeres length, which were 17% longer (p = .076).

Conclusion:

Our findings show weak differences in some cardiometabolic and placental status markers by foetal sex. Notwithstanding, we observed a slightly more proatherogenic profile in both, mothers carrying males’ foetuses and male new-borns. We also found lower serum uric acid and better placenta status in mothers carrying a female. These findings indicate that foetal sex might need to be considered for a more personalized follow-up of pregnancies.

Risk factors involved in adolescent obesity: an integrative review

The scope of this study was to examine the risk factors for the development of obesity in adolescence. The objective was to identify risk factors for adolescent obesity by means of an Integrative Review of the Literature. The PICO strategy was used to formulate the following central line of inquiry: What are the risk factors for the development of obesity during adolescence? The VHL and EBSCOhost research databases were consulted, resulting in a selection of 25 articles for in-depth study. The phenomenon of obesity was understood as the result of biological, social, psychological, and nutritional factors. The research revealed a lack of consensus on the risks and benefits, which makes evidence-based recommendations difficult. The study identified proposals that can be implemented, such as a change in eating habits, weight control and the practice of physical exercise. Such behavioral changes can be recommended within the context of the family, schools, and health services. The review recommends prevention strategies and the recognition of school as the ideal medium for health promotion through education. From a political and social standpoint, it is necessary to challenge the prevalence of publicity of the food industry that entices adolescents to consume processed foods with high fat and sugar content.

Sialometric and Sialochemical Analysis in Individuals With Pulp Stones

The aim of this study was to analyze the saliva of patients with pulp stones, with sialometric and sialochemical tests. Eighty individuals, aged between18 and 65 years, of both sexes, were investigated. Patients were included in the pulp stone group when radiographic examination was suggestive of pulp stones in at least one permanent tooth, whereas those without this alteration were considered controls. Saliva was collected by stimulation, followed by salivary flowrate (SFR) and pH analysis tests. The organic components, such as urea (URE), glucose (GLU), total proteins (TPTs), alkaline phosphatase, creatinine (CRE), salivary amylase (SAM), and uric acid (URA), and the inorganic components, such as calcium, iron, and phosphorus, were evaluated by colorimetric techniques in an ultraviolet–visible (UV–vis) spectrophotometer. Differences among pulp stones and control groups were compared using Student’s t-test, with a significance level of p < 0.05. In both groups prevailed the female. Statistically significant differences between groups were observed for pH (p = 0.027), SFR (p = 0.002), alkaline phosphatase (p = 0.008), and URA (p = 0.005). None of the inorganic components showed significant difference (p > 0.05). In the analyses stratified by sex, difference between groups was observed for pH (p = 0.007) and URA (p = 0.003) in women. In conclusion, sialometric and sialochemical alterations occurred in patients with pulp stones, with significantly higher levels of pH, SFR, alkaline phosphatase, and URA.

Reactivity of salivary uric acid in response to social evaluative stress in African Americans

High uric acid (UA) is associated with hypertension and cardiovascular disease (CVD), both of which occur disproportionately among African Americans. High UA also predicts greater blood pressure reactivity responses to acute social stress. However, whether UA itself shows reactivity in response to stress is unknown. We evaluated salivary uric acid (sUA) and blood pressure reactivity in response to acute social stress. Healthy African Americans (N = 103; 32 % male; M age = 31.36 years), completed the Trier Social Stress Test. sUA and blood pressure measurements were taken before, during and after the stressor task. sUA showed significant reactivity and recovery, especially among older African Americans. Total sUA activation was also associated with systolic and diastolic blood pressure total activation. Findings illuminate that acute stress may be a way in which UA is implicated in hypertension and CVD, suggesting a critical need to explore UA reactivity as a novel parameter of the acute stress response.

Salivary uric acid is a predictive marker of body fat percentage in adolescents

As saliva showed to be a noninvasive source of markers useful to monitor clinical status, the hypothesis tested was that saliva may provide reliable markers able to predict the body fat accumulation in young subjects. The salivary characteristics of 248 adolescent scholars (119 girls; 14-17 years) of flow rate, pH, phosphorus, urea, and calcium concentrations were assessed in stimulated saliva (colorimetric automated technique). The concentrations of cholesterol, 7-ketocholesterol, 25-hydroxyvitamin D2 and D3, and uric acid (UA) were measured with high-performance liquid chromatography in saliva collected at home (12-hour fast). Physical examination included height, weight, and body fat percentage (%BF) measured using bioelectric impedance to classify groups in below/above the %BF cutoff. Data were evaluated using 2-way analysis of variance and multiple linear regression. No significant difference was found in the levels of 25-hydroxyvitamin D2 and D3, cholesterol, 7-ketocholesterol, phosphorus, calcium, and urea between groups above and below %BF cutoff, and the variation in salivary flow was small. Significant sex and group effects were observed for salivary UA, which was increased in adolecents with higher %BF and in males (compared to females), without sex group interaction (power = 99.8%). Sex showed a significant effect on salivary urea, with lower levels in females. A predictive model was obtained, with salivary UA and sex explaining the variation of %BF (P < .001; power = 84%). Salivary UA showed to be an important marker of body fat accumulation in adolescents, demonstrating the clinical relevance of saliva to detect early changes and to monitor the nutritional status using a noninvasive and accurate method.

Nonlinear relationship between serum uric acid and body mass index: a cross-sectional study of a general population in coastal China

Background

Conflicting evidence exists on the relationship between body mass index (BMI) and serum uric acid (SUA). Therefore, we aimed to evaluate the SUA–BMI relationship in a large-scale epidemiological survey in coastal China.

Methods

This survey was conducted among the general population in the coastal region of China from September 2014 to January 2015. SUA Levels were measured by the automatic Sysmex Chemix-180 biochemical analyzer.

Results

A total of 6098 men (BMI: 24.58 ± 3.74 kg/m²) and 7941 women (24.56 ± 3.64 kg/m²) were included in this study. A stronger positive BMI-SUA association was found for men than women (all P-values < 0.05). The piecewise linear spline models indicated a U-shaped relationship of SUA-BMI association for both men and women; and the lowest turning points were at 19.12 kg/m² for men and 21.3 kg/m² for women. When BMIs were lower than the nadir point, each 1 kg/m² increase in BMI related to a 7.74-fold (95% CI − 14.73, − 0.75) reduction for men and 2.70-fold reduction (− 4.47, − 0.94) for women in SUA levels. Once the BMI was higher than the nadir point, each 1 kg/m² increase in BMI was related to a 5.10-fold (4.44, 5.77) increment for men and 3.93-fold increment (3.42, 4.43) for women in SUA levels. The regression coefficient differences between the two stages were 12.84 (5.66, 20.03) for men and 6.63 (4.65, 8.61) for women.

Conclusions

A U-shaped relationship between BMI and SUA was found for both men and women; the association was stronger for men than women.

Salivary markers of hepato-metabolic comorbidities in pediatric obesity

BACKGROUND

The pediatric obesity epidemic calls for the noninvasive detection of individuals at higher risk of complications.

AIMS

To investigate the diagnostic role of combined salivary uric acid (UA), glucose and insulin levels to screen noninvasively for metabolic syndrome (MetS) and nonalcoholic fatty liver disease.

METHODS

Medical history, clinical, anthropometric, and laboratory data including serum triglyceride, glucose, insulin, HOMA, HDL-cholesterol, and UA levels of 23 obese children (15 with [St+] and 8 without [St-] ultrasonographic hepatic steatosis) and 18 normal weight controls were considered.

RESULTS

Serum and salivary UA (p < 0.05; R² = 0.51), insulin (p < 0.0001; R² = 0.79), and HOMA (p < 0.0001; R² = 0.79) levels were significantly correlated; however their values tended to be only slightly higher in the obese patients, predominately in [St+], than in the controls. Notably, UA and insulin levels in both fluids increased in parallel to the number of MetS components. After conversion of the z-logit function including salivary/anthropometric parameters in a stepwise logistic regression analysis, a factor of 0.5 allowed for predicting hepatic steatosis with high sensitivity, specificity, and total accuracy.

CONCLUSIONS

Salivary testing together with selected anthropometric parameters helps to identify noninvasively obese children with hepatic steatosis and/or having MetS components.

Salivary uric acid: Associations with resting and reactive blood pressure response to social evaluative stress in healthy African Americans

High levels of uric acid are associated with greater risk of stress-related cardiovascular illnesses that occur disproportionately among African Americans. Whether hyperuricemia affects biological response to acute stress remains largely unknown, suggesting a need to clarify this potential connection. The current study examined how salivary uric acid (sUA) is associated with resting and reactive blood pressure - two robust predictors of hypertension and related cardiovascular disease and disparity. Healthy African Americans (N = 107; 32% male; M age = 31.74 years), completed the Trier Social Stress Test to induce social-evaluative stress. Systolic and diastolic blood pressure readings were recorded before, during, and after the task to assess resting and reactive change in blood pressure. Participants also provided a saliva sample at baseline that was assayed for sUA. At rest, and controlling for age, sUA was modestly associated with higher systolic (r = .201, p =  .044), but not diastolic (r = .100, p =  .319) blood pressure. In response to the stressor task, and once again controlling for age, sUA was also associated with higher total activation of both systolic (r = .219, p =  .025) and diastolic blood pressure (r = .198, p <  .044). A subsequent moderation analysis showed that associations between sUA and BP measures were significant for females, but not for males. Findings suggest that uric acid may be implicated in hypertension and cardiovascular health disparities through associations with elevated blood pressure responses to acute social stress, and that low levels of uric acid might be protective, particularly for females.

Household fear of deportation in relation to chronic stressors and salivary proinflammatory cytokines in Mexican-origin families post-SB 1070

Sociologists recognize that immigration enforcement policies are forms of institutionalized racism that can produce adverse health effects in both undocumented and documented Latinos and Mexican-origin persons in the United States. Despite this important advancement, little research examines the relationship between fear of immigration enforcement and biobehavioral health in mixed-status Mexican-origin families. This study applies an embodiment of racism approach to examine how household fear of deportation (FOD) is related to differences in salivary proinflammatory cytokines (IL-1 β , IL-6, IL-8, and TNF α ) in healthy Mexican-origin families with at least one immigrant, living in Phoenix, AZ. Participants were 111 individuals (n=46 adults, 72% female; n=65 children, 49% female) from 30 low-income, mixed-status families. During a home visit, anthropometric measures and saliva were collected from each family member and a household survey was administered. Saliva was assayed for salivary IL-1 β , IL-6, IL-8, and TNF α . Random effects multilevel structural equation models estimated the relationship between household FOD and a salivary proinflammatory cytokine latent variable between families, while controlling for other chronic stressors (economic/occupational, immigration, parental, and family conflict). Household FOD ( β =0.68, p=0.04) and family conflict chronic stress ( β =1.96, p=0.03) were strongly related to elevated levels of proinflammatory cytokines between families. These results were consistent in non-mixed and mixed-status families. Future research is needed to characterize what aspects of living with an undocumented family member shape the physical health outcomes of persons with authorized status or US-citizenship.

The validity, stability, and utility of measuring uric acid in saliva

AIM

Serum uric acid (UA) is associated with many health conditions, including kidney, cardiovascular, and metabolic disorders. We examined the validity and stability of salivary UA as a noninvasive measure of serum UA.

MATERIALS & METHODS

Using serum and salivary UA data from healthy adults (n = 99), we examined the UA serum-saliva correlation, and UA associations with adiponectin and C-reactive protein. Using longitudinal data from young adults (n = 182), we examined salivary UA stability.

RESULTS

We found robust positive serum-saliva correlations for UA. UA and adiponectin were inversely related in serum and saliva. Salivary UA was relatively stable; 62-66% of variance could be attributed to a latent trait-like component.

CONCLUSION

Salivary UA may be an important biomarker indexing health and disease risk.

Salivary uric acid and C-reactive protein associations with hypertension in Midwestern Latino preadolescents and their parents

Latino families face increased risk for hypertension. Serum-based uric acid and C-reactive protein have been linked to hypertension. However, a paucity of salivary biomarker data exists in this area for Latino families. Using salivary biomarkers enables less invasive options for biomedical and biosocial research, which is especially important among vulnerable populations facing increased health disparities. This study examined the associations between salivary uric (sUA) acid, salivary C-reactive protein (sCRP), and hypertension among 151 participants (57 children, 57 mothers, 37 fathers) from 57 Midwestern Latino families. Participants self-administered the salivary samples, and blood pressure was measured by researchers. Results showed sUA was associated across family members, and child hypertension was related to parents' hypertension. sCRP was only related to sUA in fathers. Findings highlight the family-level health connections, along with the importance for further investigations using salivary biomarkers with Latinos, and the need for a robust sUA cut-off for hyperuricemia.

Household fear of deportation in Mexican-origin families: Relation to body mass index percentiles and salivary uric acid

OBJECTIVE

Fear of deportation (FOD) is a prevalent concern among mixed-status families. Yet, our understanding of how FOD shapes human health and development is in its infancy. To begin to address this knowledge gap, we examined the relationship between household FOD, body mass index (BMI) percentiles and salivary uric acid (sUA), a biomarker related to oxidative stress/hypertension/metabolic syndrome, among 111 individuals living in Mexican-origin families.

METHODS

Participants were 65 children (2 months-17 years, 49% female) and 46 adults (20-58 years, 71% female) living in 30 Mexican-origin families with at least one immigrant parent in Phoenix, AZ. We recruited families using cluster probability sampling of 30 randomly selected census tracts with a high proportion of Hispanic/Latino immigrants. The head of household completed a survey containing demographic, FOD, and psychosocial measures. All family members provided saliva (later assayed for sUA) and anthropometric measures. Relationships between household FOD, BMI percentile, and sUA levels were estimated using multilevel models.

RESULTS

Higher levels of household FOD were associated with lower BMI percentiles and lower sUA levels between families, after controlling for social support and socioeconomic proxies.

CONCLUSION

Key features of the social ecology in which mixed-status families are embedded are associated with individual differences in biological processes linked to increased risk for chronic disease.