The interplay between uric acid and antioxidants in relation to physical function in older persons

Skeletal muscle mass and quality in gout patients versus non-gout controls: A computed tomography imaging study

OBJECTIVE

Patients with gout are at elevated risk of multiple vascular and metabolic comorbidities. Whether they are also at risk of sarcopenia, which is known to affect patients with other rheumatic diseases, has not been previously assessed. We examined whether patients with gout have decreased lumbar muscle quality and quantity, indicating an association between gout and sarcopenia.

METHODS

Fifty gout subjects and 25 controls, ages 45-80, underwent computed tomography imaging of the lumbosacral spine. We measured muscle quantity (skeletal muscle area [SMA] and index [SMI]) and quality (skeletal muscle radiation attenuation [SMRA] and intermuscular adipose tissue [IMAT] area and index [IMATI]) of the psoas and erector spinae muscles at the L3 level.

RESULTS

Seventy subjects (45 gout and 25 controls) were included in the analysis. Gout subjects had higher BMI, more kidney disease and hypertension, lower exercise frequency, and higher mean serum urate and creatinine vs. controls. Lumbar SMRA was significantly lower in gout subjects vs. controls, indicating reduced muscle quality. Lumbar IMAT area was significantly higher in gout subjects vs. controls, as was lumbar IMATI, indicating increased muscle adiposity. These differences persisted after adjusting for potential confounders. In contrast, there was no significant difference between gout and control groups in lumbar SMA or lumbar SMI, suggesting that muscle quantity may not be routinely affected by the diagnosis of gout.

CONCLUSIONS

Gout patients exhibit decreased lumbar muscle quality compared with controls, consistent with an association between gout and sarcopenia.

Fructose-induced hyperuricaemia - protection factor or oxidative stress promoter?

Accumulating evidence suggests that dietary fructose may play a role in the hyperuricaemia development, but the precise mechanism remains unclear. Hyperuricaemia is characterised by excessive production and deposition of urate crystals, and the metabolism of fructose has been implicated in the elevation of serum urate levels. The association between fructose intake and the risk of hyperuricaemia is explained by the metabolism of fructose in the liver, small intestine, and kidney. Many studies have confirmed the correlation between fructose consumption and an increased risk of developing hyperuricaemia, but more prospective studies to fully elucidate the role of fructose intake in the pathogenesis of hyperuricaemia are needed. It is important to note that maintaining a balanced diet, and lifestyle is crucial when considering fructose intake. Limiting the consumption of products high in added sugars and maintaining a healthy weight can contribute to reducing the risk of hyperuricaemia and associated health complications.

Composite Dietary Antioxidant Index Is Negatively Associated with Hyperuricemia in US Adults: An Analysis of NHANES 2007-2018

Hyperuricemia and its complications are severe risks to human health. Dietary intervention is considered an essential part of the management of hyperuricemia. Studies have reported that the intake of antioxidants has a positive effect on hyperuricemia. Here, we collected data from 8761 participants of the National Health and Nutrition Examination Survey for this analysis. Daily intakes of vitamins A, C, and E; manganese; selenium; and zinc were calculated as the composite dietary antioxidant index (CDAI). The participants were divided into four groups (Q1, Q2, Q3, and Q4) according to the CDAI. Univariate analysis was used to assess the association of covariates with hyperuricemia. The association between the CDAI and hyperuricemia was evaluated using multinomial logistic regression, and its stability was determined by stratified analysis. Our results revealed that the CDAI has a significant negative association with hyperuricemia (Q2: 0.81 (0.69, 0.95); Q3: 0.75 (0.62, 0.90); Q4: 0.65 (0.51, 0.82); P < 0.01). The results of stratified analysis emphasize that this association between CDAI and hyperuricemia is stable. In conclusion, this study suggested a negative association between the CDAI and hyperuricemia.

Combined Exposure to Multiple Metals and Kidney Function in a Midlife and Elderly Population in China: A Prospective Cohort Study

[Background] Metal exposure is suspected to be correlated to kidney function. However, the combined effects of co-exposing to multiple metals, especially both toxic and protective metals, have not been completely evaluated. [Method] A prospective cohort study was conducted with the "135" cohort for the evaluation of how plasma metal levels are correlated to kidney function in a midlife and elderly community in southern China. An amount of 1368 subjects without kidney disease at baseline were enrolled in the final analysis. By using linear regression and logistic regression models, the correlation of individual metal values with renal function parameters was assessed. Measuring of the multiple metal exposure level was performed by principal component analysis (PCA). [Results] Diminished renal function, as evaluated based on fast kidney function decline, or estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m², was positively associated with the plasma concentrations of chromium and potassium, but it was negatively associated with selenium and iron (p < 0.05). In multiple-metal analyses, linear and logistic regression models showed that the iron and chromium exposure pattern had a protective effect on renal function, whereas the sodium and potassium exposure pattern and the cadmium and lead exposure pattern increased the risk for fast kidney function decline, and eGFR < 60 mL/min/1.73 m². [Conclusions] Certain metals, including chromium, potassium, selenium, and iron, were correlated with kidney function in a midlife and elderly community in China. In addition, the potential combined influences of co-exposing to multiple metals were observed.

A metabolome-wide association study of in utero metal and trace element exposures with cord blood metabolome profile: Findings from the Boston Birth Cohort

BACKGROUND

Exposure to metals lead (Pb), mercury (Hg), and cadmium (Cd) and trace elements selenium (Se) and manganese (Mn) has been linked to the developmental origins of cardiometabolic diseases, but the mechanisms are not well-understood.

OBJECTIVE

Conduct a metabolome-wide association study to understand how in utero exposure to Pb, Hg, Cd, Se, and Mn affects the metabolic programming of fetuses.

METHODS

We used data from the Boston Birth Cohort, which enrolled mother-child pairs from Boston, MA. We measured metals and trace elements in maternal red blood cells (RBCs) collected 24-72 h after delivery, and metabolites in cord blood collected at birth. We used multivariable linear regression to examine associations of metals and trace elements with metabolites and Bonferroni correction to account for multiple comparisons. We assessed non-linear associations of metals and trace elements with metabolites using restricted cubic spline plots.

RESULTS

This analysis included 670 mother-child pairs (57% non-Hispanic Black and 24% Hispanic). After Bonferroni correction, there were 25 cord metabolites associated with at least one of the metals or trace elements. Pb was negatively associated with the xenobiotic piperine, Cd was positively associated with xenobiotics cotinine and hydroxycotinine, and Hg was associated with 8 lipid metabolites (in both directions). Se and Mn shared associations with 6 metabolites (in both directions), which mostly included nucleotides and amino acids; Se was additionally associated with 7 metabolites (mostly amino acids, nucleotides, and carnitines) and Mn was additionally associated with C36:4 hydroxy phosphatidylcholine. Restricted cubic spline plots showed that most associations were linear.

DISCUSSION

Maternal RBC metal and trace element concentrations were associated in a dose-dependent fashion with cord blood metabolites. What remains to be determined is whether these metals- and trace elements-associated changes in cord metabolites can influence a child's risk of cardiometabolic diseases.

Associations of plasma multiple metals with risk of hyperuricemia: A cross-sectional study in a mid-aged and older population of China

BACKGROUND

Metal exposures are suspected to associate with the risk of hyperuricemia (HUA), but the current results are still conflicting.

OBJECTIVE

To investigate the associations between multiple plasma metal exposures and HUA risk.

METHODS

A cross-sectional study was conducted in 1406 Chinese Han adults who underwent routine physical examination in the Eighth Affiliated Hospital of Sun Yat-Sen University in Shenzhen. The plasma levels of 13 metals were measured by the inductively coupled plasma mass spectrometry (ICP-MS). Multivariable logistic, linear regression models, least absolute shrinkage and selection operator (LASSO) penalized regression analysis, and restricted cubic spline (RCS) models were applied to assess the associations.

RESULTS

The median plasma uric acid concentration in HUA group (434 μmol/L) was significantly higher than that in non-HUA group (305 μmol/L). The multivariate-adjusted odds ratios (95% confidence intervals) of HUA were 1.62(1.08-2.43) for magnesium, 1.61(1.05-2.47) for copper, 1.62(1.06-2.49) for zinc, 1.87(1.26-2.81) for arsenic, 1.50(1.01-2.23) for selenium, and 1.70(1.16-2.49) for thallium based on the single-metal logistic regression models, comparing the highest versus the lowest quartile of metal levels. Further multi-metal logistic, linear regression models and the LASSO analysis all indicated positive associations of zinc, arsenic with HUA risk or uric acid levels. RCS model indicated an inverted V-shaped positive association between zinc levels and HUA risk (p for non-linearity = 0.048, p for overall association = 0.022), while arsenic levels showed a positive and linear dose-response relationship with HUA risk (p for non-linearity = 0.892, p for overall association<0.001).

CONCLUSIONS

Higher plasma levels of zinc and arsenic might increase HUA risk and showed positive dose-response relationships. Further cohort studies in larger population are required to testify our findings.

Selenium in Human Health and Gut Microflora: Bioavailability of Selenocompounds and Relationship With Diseases

This review covers current knowledge of selenium in the dietary intake, its bioavailability, metabolism, functions, biomarkers, supplementation and toxicity, as well as its relationship with diseases and gut microbiota specifically on the symbiotic relationship between gut microflora and selenium status. Selenium is essential for the maintenance of the immune system, conversion of thyroid hormones, protection against the harmful action of heavy metals and xenobiotics as well as for the reduction of the risk of chronic diseases. Selenium is able to balance the microbial flora avoiding health damage associated with dysbiosis. Experimental studies have shown that inorganic and organic selenocompounds are metabolized to selenomethionine and incorporated by bacteria from the gut microflora, therefore highlighting their role in improving the bioavailability of selenocompounds. Dietary selenium can affect the gut microbial colonization, which in turn influences the host's selenium status and expression of selenoproteoma. Selenium deficiency may result in a phenotype of gut microbiota that is more susceptible to cancer, thyroid dysfunctions, inflammatory bowel disease, and cardiovascular disorders. Although the host and gut microbiota benefit each other from their symbiotic relationship, they may become competitors if the supply of micronutrients is limited. Intestinal bacteria can remove selenium from the host resulting in two to three times lower levels of host's selenoproteins under selenium-limiting conditions. There are still gaps in whether these consequences are unfavorable to humans and animals or whether the daily intake of selenium is also adapted to meet the needs of the bacteria.

Cross-sectional analysis of the association between serum uric acid levels and handgrip strength among Chinese adults over 45 years of age

Background

Sarcopenia is the decline in muscle strength and mass attributed to aging. The pathogenesis of sarcopenia may be triggered by oxidative stress; uric acid (UA) has strong antioxidant properties. This study aimed to examine if the serum UA level is associated with handgrip strength (HGS), which is a useful indicator of sarcopenia among Chinese participants aged over 45.

Methods

Our study included 992 eligible participants (583 males and 409 females). Based on serum UA quartiles and gender, the participants were divided into 8 groups. HGS was measured in kilograms using an electronic dynamometer. Face-to-face visits and fasting blood analyses were performed to determine the serum UA levels and various covariates. Univariate analysis of variance (ANOVA) and covariance (ANCOVA) was conducted to analyze the linear or quadratic trend between the UA levels and grip strength.

Results

Participants were grouped according to UA quartiles by gender. In both genders, ANOVA showed an inverted J-shaped association between serum UA levels and HGS (P for quadratic trend =0.004 in men, P for quadratic trend =0.003 in women). After adjusting for potential confounders, the association between the UA quartiles and HGS was unchanged, irrespective of gender.

Conclusions

The results suggest that a specific range of serum UA levels may be associated with better HGS among Chinese adults aged over 45.

The Role of the Gut Microbiota in Coronary Heart Disease

PURPOSE OF REVIEW

This review focuses on recent evidence examining the role gut microbiota play in coronary heart disease. It also provides a succinct overview of current and future therapies targeting the gut microbiota for coronary heart disease risk reduction.

RECENT FINDINGS

A consensus has been reached that differences exist in the gut microbiotas of patients with coronary heart disease. Studies have shown that the gut microbiota is associated with obesity, diabetes, dyslipidemia, and hypertension, which are risk factors for coronary heart disease. The gut microbiota is involved in mediating basic metabolic processes, such as cholesterol metabolism, uric acid metabolism, oxidative stress, and inflammatory reactions, through its metabolites, which can induce the development of atherosclerosis and coronary heart disease. Interfering with the composition of gut microbiota, supplementing probiotics, and fecal donation are active areas of research to potentially prevent and treat coronary heart disease. Gut microbiota are causally associated with coronary heart disease. We analyzed the gut microbiota's effects on risk factors for coronary heart disease and studied the effects of gut microbiota metabolites on coronary heart disease. Gut microbiota is a potential target for preventing and treating coronary heart disease.

Antioxidant therapy (lycopene and green tea extract) in periodontal disease: A promising paradigm

Background

Increased oxidative stress has emerged as one of the prime factors in the pathogenesis of periodontitis. Hence, antioxidant therapy may become a promising tool in the treatment of periodontal disease. Uric acid (UA) being a major antioxidant in saliva can be used as a marker to assess the total antioxidant capacity.

Aim

The aim of the study was to investigate the influence of orally administered antioxidants (lycopene and green tea extract) on periodontal health and salivary UA levels in gingivitis patients as an adjunct to scaling and root planing (SRP).

Materials and Methods

Thirty systemically healthy participants having generalized gingivitis were randomly distributed into two groups. Control group participants received full mouth oral prophylaxis, while test group participants received oral lycopene and green tea extract (CLIK^®) for 45 days along with complete oral prophylaxis. Plaque index (PI), sulcular bleeding index (SBI), and salivary UA levels were evaluated at baseline and 45 days after SRP. Data were analyzed with t-test, using SPSS software (PASW, Windows version 18.0).

Results

Both treatment groups demonstrated statistically highly significant (P ≤ 0.001) reduction in plaque and SBI. After treatment, a highly significant increase (P ≤ 0.001) in the test group and significant (P ≤ 0.05) increase in the control group was observed for salivary UA levels. Posttreatment comparison between test and control group delineated statistically significant results in PI (P ≤ 0.001), SBI (P ≤ 0.001), and salivary UA levels (P ≤ 0.01).

Conclusion

Lycopene with green tea extract may prove to be a promising adjunctive prophylactic and therapeutic modality in the treatment of gingivitis patients. However, further studies are needed to evaluate the additive effect of antioxidants with routine oral prophylaxis therapy.

Uric acid enhances longevity and endurance and protects the brain against ischemia

Among mammals, there is a positive correlation between serum uric acid (UA) levels and life span. Humans have high levels of UA because they lack a functional urate oxidase (UOX) enzyme that is present in shorter lived mammals. Here, we show that male and female mice with UOX haploinsufficiency exhibit an age-related elevation of UA levels, and that the life span of female but not male UOX+/- mice is significantly increased compared to wild-type mice. Serum UA levels are elevated in response to treadmill exercise in UOX+/- mice, but not wild-type mice, and the endurance of the UOX+/- mice is significantly greater than wild-type mice. UOX+/- mice exhibit elevated levels of brain-derived neurotrophic factor, reduced brain damage and improved functional outcome in a model of focal ischemic stroke. Levels of oxidative protein nitration and lipid peroxidation are reduced in muscle and brain tissues of UOX+/- mice under conditions of metabolic and oxidative stress (running in the case of muscle and ischemia in the case of the brain), consistent with prior evidence that UA can scavenge peroxynitrite and hydroxyl radical. Our findings reveal roles for UA in life span determination, endurance and adaptive responses to brain injury, and suggest novel approaches for protecting cells against injury and for optimizing physical performance.

Characteristics of hyperuricemia in older adults in China and possible associations with sarcopenia

OBJECTIVE

This cross-sectional study aimed to investigate the characteristics and epidemiology of hyperuricemia in older adults in China and evaluate possible associations between hyperuricemia and sarcopenia.

METHODS

Three hundred and eighty-eight study subjects (>60 years old) meeting the inclusion criteria received blood tests and standardized examinations for bone mineral density, muscle mass, muscle strength, and physical performance. Data including demographic and clinical characteristic and comorbidity were also collected. All data were analyzed retrospectively.

RESULTS

In the study population, higher uric acid levels were significantly correlated with higher muscle mass, grip strength, and bone density, but were unrelated to physical performance. When uric acid levels were separated into quartiles and the population was divided by sex, the correlation of uric acid to muscle mass was retained in some quartiles for both men and women, and the correlation to handgrip was only retained for one quartile for men. The correlation to bone density was retained in women in all analyses.

CONCLUSION

In the population as a whole, higher uric acid levels were significantly correlated with higher muscle mass, grip strength, and bone density, but had no relationship to physical performance. Differences between men and women in these relationships need to be studied further.

Serum Uric Acid Is Positively Associated with Handgrip Strength among Japanese Community-Dwelling Elderly Women

Serum uric acid (UA) has strong anti-oxidant properties. Muscle strength and mass decrease with age, and recently, this decrease has been defined as sarcopenia. Sarcopenia may be triggered by oxidative stress. We investigated whether serum UA is associated with handgrip strength (HGS), which is a useful indicator of sarcopenia, among Japanese community-dwelling elderly persons. The present study included 602 men aged 72 ± 7 years and 847 women aged 71 ± 6 years from a rural village. We examined the cross-sectional relationship between serum UA and HGS. In both genders, HGS increased significantly with increased serum UA levels. A multiple linear regression analysis using HGS as an objective variable and various confounding factors as explanatory variables showed that in men age, drinking status, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and estimated glomerular filtration ratio (eGFRCKDEPI) were independently and significantly associated with HGS, and in women, serum UA as well as age, body mass index, drinking status, diastolic blood pressure, and eGFRCKDEPI were independently and significantly associated with HGS. In women, age and multivariate-adjusted HGS were significantly higher in the Quartile-3 (4.8-5.4 mg/dL) and Quartile-4 groups (5.5-9.3 mg/dL) of serum UA than in the lower groups (0.7-4.7 mg/dL). These results suggest that serum UA may have a protective role in aging-associated decline in muscle strength in community-dwelling elderly women.

Vitamin D deficiency associates with γ-tocopherol and quadriceps weakness but not inflammatory cytokines in subjects with knee osteoarthritis

Knee osteoarthritis (OA) is a degenerative joint condition and a leading cause of physical disability in the United States. Quadriceps weakness and inflammatory cytokines contribute to the pathogenesis of knee OA, and both of which, increase with vitamin D deficiency. Other micronutrients, such as vitamins C and E and β-carotene, modulate inflammatory cytokines and decrease during inflammation. The purpose of this study was to test the hypothesis that vitamin D deficiency associates with quadriceps weakness, an increase in serum cytokines, and a decrease in circulating micronutrients in subjects with knee OA. Subjects (age, 48±1 y; serum 25(OH)D, 25.8±1.1 ng/mL) with knee OA were categorized as vitamin D deficient (n=17; serum 25(OH)D≤20 ng/mL), insufficient (n=21; serum 25(OH)D 20–29 ng/mL), or sufficient (n=18; serum 25(OH)D≥30 ng/mL). Single-leg strength (concentric knee extension–flexion contraction cycles at 60 °/s) and blood cytokine, carotene (α and β), ascorbic acid, and tocopherol (α and γ) concentrations were measured. Quadriceps peak torque, average power, total work, and deceleration were significantly (all p<0.05) impaired with vitamin D deficiency. Serum γ-tocopherol concentrations were significantly (p<0.05) increased with vitamin D deficiency. In the vitamin D sufficient group, γ-tocopherol inversely correlated (r=−0.47, p<0.05) with TNF-α, suggesting a pro-inflammatory increase with a γ-tocopherol decrease despite a sufficient serum 25(OH)D concentration. We conclude that vitamin D deficiency is detrimental to quadriceps function, and in subjects with vitamin D sufficiency, γ-tocopherol could have an important anti-inflammatory role in a pathophysiological condition mediated by inflammation.

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We investigated the vitamin D association with mediators of knee osteoarthritis.

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Vitamin D deficiency associated with quadriceps dysfunction.

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Vitamin D deficiency was not associated with serum cytokines.

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Vitamin D deficiency associated with increased plasma γ-tocopherol concentrations.

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γ-Tocopherol inversely correlated with TNF-α in vitamin D sufficient subjects.

An inverted J-shaped association of serum uric acid with muscle strength among Japanese adult men: a cross-sectional study

Background

Uric acid (UA) may protect muscle function from oxidative damage due to reactive oxygen species through its powerful antioxidant capacity. However, several studies have demonstrated that hyperuricemia is closely related to systemic inflammation and has oxidant properties effects, both of which may increase the risk of muscle strength loss. The purpose of this study was to examine the association of serum UA concentration with grip strength and leg extension power in adult men.

Methods

This study is a cross-sectional survey in which 630 Japanese male employees aged 30 years and older participated. Five hundred and eighty-six subjects participated in the measurement of grip strength, and 355 subjects participated in the measurement of leg extension power. Blood samples were obtained for serum UA analysis.

Results

After adjustment for potential confounders, grip strength differed significantly between participants with and those without hyperuricemia (geometric mean and 95% confidence interval [CI]: 40.3 [39.2–41.3] kg vs. 41.9 [41.3–42.5] kg; P = 0.01). In addition, serum UA levels (quartiles) showed an inverted J-shaped curve with grip strength (mean and 95% CI: Q1, 41.6 [40.6–42.6] kg; Q2, 42.2 [41.2–43.2] kg; Q3, 41.8 [40.8–42.8] kg; Q4, 40.4 [39.3–41.4] kg; P for quadratic trend = 0.05). The results in the leg extension power group were similar to those observed in the grip strength group.

Conclusion

This population-based cross-sectional study shows for the first time that hyperuricemia is associated with poor muscle strength. Moreover, the results indicate an inverted J-shaped association between serum UA quartiles and muscle strength.

The effects of a long-term physical activity intervention on serum uric acid in older adults at risk for physical disability

Observational studies show a relationship between elevated serum uric acid (UA) and better physical performance and muscle function. The purpose of this paper was to determine whether regular participation in an exercise intervention, known to improve physical functioning, would result in increased serum UA. For this study, 424 older adults at risk for physical disability were randomized to participate in either a 12-mo moderate-intensity physical activity (PA) or a successful aging (SA) health education intervention. UA was measured at baseline, 6, and 12 mo (n = 368, 341, and 332, respectively). Baseline UA levels were 6.03 ± 1.52 mg/dl and 5.94 ± 1.55 mg/dl in the PA and SA groups, respectively. The adjusted mean UA at month 12 was 4.8% (0.24 mg/dl) higher in the PA compared with the SA group (p = .028). Compared with a health education intervention, a 1-yr PA intervention results in a modest increase in systemic concentration of UA in older adults at risk for mobility disability.

Relationship of 25-hydroxyvitamin D with all-cause and cardiovascular disease mortality in older community-dwelling adults

BACKGROUND/OBJECTIVES

Vitamin D deficiency is associated with cardiovascular disease, osteoporosis, poor muscle strength, falls, fractures and mortality. Although older adults are at a higher risk of vitamin D deficiency, the relationship of serum 25-hydroxyvitamin D (25(OH)D) with all-cause and cardiovascular disease mortality has not been well characterized in the elderly. We hypothesized that low serum 25(OH)D levels predicted mortality in older adults.

SUBJECTS/METHODS

Serum 25(OH)D as well as all-cause and cardiovascular disease mortality were examined in 1006 adults, aged > or =65 years, who participated in the InCHIANTI (Invecchiare in Chianti, Aging in the Chianti Area) study, a population-based, prospective cohort study of aging in Tuscany, Italy. Serum 25(OH)D levels were measured at the time of enrollment in 1998-1999, and participants were followed up for mortality.

RESULTS

During 6.5 years of follow-up, 228 (22.7%) participants died, of whom 107 died due to cardiovascular diseases. Compared with participants in the highest quartile of serum 25(OH)D (>26.5 ng/ml) (to convert to nmol/l, multiply by 2.496), those in the lowest quartile (<10.5 ng/ml) had increased risk of all-cause mortality (Hazard Ratio (H.R.) 2.11, 95% Confidence Interval (95% C.I.): 1.22-3.64, P=0.007) and cardiovascular disease mortality (H.R. 2.64, 95% C.I.: 1.14-4.79, P=0.02), in multivariate Cox proportional hazards models that adjusted for age, sex, education, season, physical activity and other potential confounders.

CONCLUSIONS

Older community-dwelling adults with low serum 25(OH)D levels are at higher risk of all-cause and cardiovascular disease mortality.