Mercury, natural fertility and outcomes of assisted reproduction: A systematic review.

The primary route of mercury exposure for the general population is through consumption of contaminated seafood. There is a biological basis for an adverse effect of mercury exposure on human fertility. The goal of this review was to evaluate the existing literature on the association between mercury and pregnancy, among men and women attempting to conceive with and without assisted reproductive technology (ART). Systematic searches were performed in PubMed, EMBASE, Scopus and Web of Science for papers published up to March 2023 with no early date restriction, only including studies with a biomarker measurement of mercury exposure. We identified 11 studies examining mercury and natural fertility and 12 studies examining mercury and outcomes of assisted reproduction (implantation or clinical pregnancy). The accumulated evidence provides some support for a null association between bodily mercury concentrations and natural fertility among women, however, a large proportion of studies did not report adjusted estimates or were extremely imprecise. The majority of studies of natural fertility were also cross-sectional in nature. There was no evidence for an inverse or null association between mercury and natural fertility among men, or mercury and ART outcomes among men or women. In spite of biological plausibility, the existing evidence includes studies that are imprecise and often conflicting and does not allow us to make definitive conclusions on the associations of mercury exposure with successful pregnancy. Additional, larger studies are warranted, especially among individuals with high concentrations of mercury exposure as these individuals may be underrepresented in the current literature.

One-Carbon Metabolism Nutrients, Genetic Variation, and Diabetes Mellitus.

Diabetes mellitus (DM) affects about 9.3% of the population globally. Hyperhomocysteinemia (HHcy) has been implicated in the pathogenesis of DM, owing to its promotion of oxidative stress, ß-cell dysfunction, and insulin resistance. HHcy can result from low status of one-carbon metabolism (OCM) nutrients (e.g., folate, choline, betaine, vitamin B6, B12), which work together to degrade homocysteine by methylation. The etiology of HHcy may also involve genetic variation encoding key enzymes in OCM. This review aimed to provide an overview of the existing literature assessing the link between OCM nutrients status, related genetic factors, and incident DM. We also discussed possible mechanisms underlying the role of OCM in DM development and provided recommendations for future research and practice. Even though the available evidence remains inconsistent, some studies support the potential beneficial effects of intakes or blood levels of OCM nutrients on DM development. Moreover, certain variants in OCM-related genes may influence metabolic handling of methyl-donors and presumably incidental DM. Future studies are warranted to establish the causal inference between OCM and DM and examine the interaction of OCM nutrients and genetic factors with DM development, which will inform the personalized recommendations for OCM nutrients intakes on DM prevention.

The association between lead exposure and dental caries ─ a systematic review.

INTRODUCTION: Dental caries has declined over the years, but it remains a major public health issue. This review aimed to investigate the association between lead and caries experience in either deciduous or permanent teeth. METHODS: A comprehensive search of PubMed, EMBASE, and Google Scholar was conducted to identify relevant studies published up until December 2022. Included were human observational studies that investigated the association between lead exposure and dental caries. The review adhered to the PRISMA guideline. RESULTS: Sixteen studies were included in this review, with nine focusing on deciduous teeth, thirteen on permanent teeth, and six examining both types of teeth. Most of the studies (5 of 6) found a positive association between blood lead (PbB) levels and caries in deciduous teeth, while the findings for permanent teeth were less conclusive, with only 3 of 10 studies finding an association. One of the two studies assessing salivary lead (PbSa) levels found a weak association for permanent teeth. All four studies that examined lead (Pb) concentration in teeth found a positive association for both deciduous and permanent teeth. CONCLUSION: Many published studies indicated a positive association between Pb exposure and caries experience in deciduous dentition. Children with elevated PbB level should be considered as having higher caries experience. Due to lack of consensus on measurement and examination technique, there remains insufficient evidence to make any definitive conclusions especially in permanent teeth, and so more studies are warranted.

Serum zinc concentration and dietary zinc intake in relation to cognitive function: an analysis of the REasons for Geographic and Racial Differences in Stroke (REGARDS) cohort.

PURPOSE: There are several pathways by which zinc may be a modifiable factor to slow age-related cognitive decline. We investigated the associations between serum and dietary zinc and cognitive impairment in a longitudinal cohort. METHODS: We used data from the REasons for Geographic and Racial Differences in Stroke (REGARDS) Cohort (n = 30,239) and the REGARDS Trace Element Study (n = 2666). Baseline serum zinc concentrations (2003-2007) were measured using inductively coupled plasma mass spectrometry. Baseline dietary zinc intake was measured via the Block food frequency questionnaire. Serum zinc concentrations and dietary zinc intake were categorized into quartiles. The outcome of interest was impairment on the Six-Item Screener (SIS), a measure of global cognitive functioning administered annually. The Enhanced Cognitive Battery (ECB), a more comprehensive series of tests assessing memory and fluency, was administered every two years and considered a secondary outcome. Associations between zinc and incident impairment were assessed using multivariable logistic regression. RESULTS: Among 2065 participants with serum zinc data, 184 individuals developed impairment over 10 years of follow-up. In adjusted models, there was no significant association between serum zinc and impairment as assessed by the SIS or the ECB. Among 18,103 participants who had dietary data, 1424 experienced incident impairment on the SIS. Dietary zinc intake was not significantly associated with impairment as assessed by the SIS or the ECB in adjusted models. CONCLUSION: Findings from this U.S. cohort did not support the hypothesis that serum zinc concentration or dietary zinc intake is associated with the risk of cognitive impairment.

Smoking Modifies the Association Between Radon Exposure and Incident Ischemic Stroke: The REGARDS Study.

BACKGROUND: Exposure to radon has been linked to lung cancer and other lung diseases. Although biologically plausible, research of residential radon exposure in relation to stroke risk is scarce. METHODS: Study participants were from the REGARDS (Reasons for Geographic and Racial Differences in Stroke) cohort (n=30 239), which consisted of male and female non-Hispanic Black and White adults aged 45 and older. After excluding participants with baseline stroke and transient ischemic attack, and missing information on exposure and outcome of interest, the final sample size was 26 950. The primary outcome was time to the first ischemic stroke through September 30, 2020. County-level radon measures from Lawrence Berkeley National Laboratory were linked to each participant based on their geocoded residential history. We used Cox proportional hazards regression models with a time-dependent exposure to estimate hazard ratios and 95% CIs for the association. RESULTS: After controlling for potential confounding factors including demographic, lifestyle, clinical variables, and PM2.5, radon exposure was significantly associated with incident ischemic stroke among never-smokers (hazard ratio, 1.39 [95% CI, 1.01-1.90]) but not ever-smokers. The results were generally consistent in the sensitivity analysis when using radon measures from state/Environmental Protection Agency residential radon survey. CONCLUSIONS: Findings from this study suggest that the association between residential radon exposure and incidence of ischemic stroke varies by smoking status and may be prominent in never-smokers. Further studies incorporating indoor-radon measures are needed to confirm these findings.

Associations of Telomere Length and Change With Cognitive Decline Were Modified by Sex and Race: The REGARDS Study.

INTRODUCTION: We examined the associations of baseline telomere length (TL) and TL change with cognitive function over time in older US adults, as well as differences by sex and race. METHODS: A total of 1820 cognitively healthy individuals (median baseline age: 63 years) were included. Telomere length was measured using qPCR-based method at baseline and among 614 participants in the follow-up examination 10 years later. Cognitive function was assessed by a four-test battery every 2 years. RESULTS: In multivariable-adjusted linear mixed models, longer baseline TL and smaller attrition/lengthening of TL over time were associated with better Animal Fluency Test score. Longer baseline TL was also linearly associated with better Letter Fluency Test score. The observed associations were consistently more pronounced in women than men and in Black compared to White participants. DISCUSSION: Telomere length may be a biomarker that predicts long-term verbal fluency and executive function, particularly in women and Black Americans.

Age modifies the association between pet ownership and cardiovascular disease.

Introduction: Studies examining associations between pet ownership and cardiovascular disease have yielded inconsistent results. These discrepancies may be partially explained by variations in age and sex across study populations. Our study included 6,632 American Gut Project participants who are US residents ≥40 years. Methods: We first estimated the association of pet ownership with cardiovascular disease risk using multivariable-adjusted logistic regression, and further investigated effect modifications of age and sex. Results: Cat but not dog ownership was significantly associated with lower cardiovascular disease risk (OR: 0.56 [0.42, 0.73] and OR: 1.17 [0.88, 1.39], respectively). Cat and dog ownership significantly interacted with age but not sex, indicating that cardiovascular risk varies by the age-by-pet ownership combination. Compared to the reference group (40-64 years, no cat or dog), participants 40-64 years with only a cat had the lowest cardiovascular disease risk (OR: 0.40 [0.26, 0.61]). Those ≥65 years with no pets had the highest risk (OR: 3.85 [2.85, 5.24]). Discussion: This study supports the importance of pets in human cardiovascular health, suggesting optimal pet choice is age-dependent. Having both a cat and dog can be advantageous to people ≥65 years, while having only a cat may benefit those 40-64 years. Further studies are needed to assess causality.

Folate, Vitamin B6, and Vitamin B12 Status in Association With Metabolic Syndrome Incidence.

Importance: The associations of B vitamin status with metabolic syndrome (MetS) incidence among the US population remain unclear. Objective: To investigate intakes and serum concentrations of folate, vitamin B6, and vitamin B12 in association with MetS risk in a large US cohort. Design, Setting, and Participants: This prospective study included Black and White young adults in the US who were enrolled from 1985 to 1986 and studied until 2015 to 2016. Diet was assessed using a validated diet history at examination years 0, 7, and 20. Serum concentrations of folate, vitamin B6, and vitamin B12 were assayed at examination years 0, 7, and 15 in a subset of 1430 participants. MetS was ascertained by clinic and laboratory measurements and self-reported medication use. Data were analyzed between January and July 2021. Exposures: Intakes and serum levels of folate, vitamin B6, and vitamin B12. Main Outcomes and Measures: Multivariable Cox proportional hazards regression models were used to calculate hazard ratios (HRs) and 95% CIs for the associations of energy-adjusted B vitamin intakes or serum B vitamin levels with incident MetS. Results: The study included 4414 participants, with 2225 Black individuals (50.4%) and 2331 women (52.8%). The mean (SD) age at baseline was 24.9 (3.6) years. A total of 1240 incident MetS cases occurred during the 30 years (mean [SD], 22.1 [9.5] years) of follow-up. Compared with the lowest quintile of each energy-adjusted B vitamin intake, the HRs for incident MetS in the highest quintile were 0.39 (95% CI, 0.31-0.49) for folate (P for trend < .001), 0.61 (95% CI, 0.46-0.81) for vitamin B6 (P for trend = .002), and 0.74 (95% CI, 0.58-0.95) for vitamin B12 (P for trend = .008) after adjustment for potential confounders. Similarly, significant inverse associations were observed in the subset with serum data on these B vitamins (folate: HR, 0.23; 95% CI, 0.17-0.33; P for trend < .001; vitamin B6: HR, 0.48; 95% CI, 0.34-0.67; P for trend < .001; and vitamin B12: HR, 0.70; 95% CI, 0.51-0.96; P for trend = .01). Conclusions and Relevance: This prospective cohort study found that intakes and serum concentrations of folate, vitamin B6, and vitamin B12 were inversely associated with incident MetS among Black and White young adults in the US.

Gestational weight gain and mode of delivery by the class of obesity: A meta-analysis.

The association between gestational weight gain (GWG) and mode of delivery in females with different obesity classes is not clear. We conducted a meta-analysis to evaluate the association between GWG, categorized according to the 2009 Institute of Medicine (IOM) guidelines, and the risk of cesarean section (CS) or operative vaginal delivery (OVD) in females with different obesity classes. Eight studies were identified. The pooled odds ratios (ORs) (95% confidence interval [CI]) of CS for females with GWG above the recommendations were 1.27 (1.20-1.33) for obesity class I, 1.22 (1.20-1.23) for class II, and 1.17 (1.15-1.19) for class III. Also, the pooled ORs (95% CI) of OVD were 1.21 (1.005-1.46) for obesity class I, 1.12 (1.04-1.21) for class II, and 1.10 (1.001-1.22) for obesity class III. GWG below the recommendations was associated with lower risk of CS for females with obesity class I (OR 0.87, 95% CI 0.82-0.92), class II (OR 0.84, 95% CI 0.77-0.90), and class III (OR 0.86, 95% CI 0.79-0.93). Pregnant participants gaining weight above the 2009 IOM guidelines were at higher risk for CS and OVD regardless of obesity classes. Gaining weight below the guidelines was associated with a lower risk of CS among females in any obesity class.

Dietary selenium intake and thyroid cancer risk in postmenopausal women.

OBJECTIVE: It has been suggested that higher selenium intake and consumption of supplements protect against several cancers. To our knowledge, epidemiologic evidence is rare and inconsistent on the association of selenium level and the risk for thyroid cancer. Therefore, the aim of this study was to examine the association between selenium intake and thyroid cancer risk in postmenopausal women using the Women's Health Initiative (WHI) database. METHODS: The WHI recruited 161 808 postmenopausal women 50 to 79 y of age between September 1, 1993 and December 31, 1998. The present study included 147 348 women 63.15 y of age (SD = 7.21) at baseline. The main exposure was baseline total selenium intake including dietary selenium measured by food frequency questionnaire (FFQ) and supplemental selenium. The outcome was thyroid cancer, which was adjudicated by trained physicians. Cox proportional hazard models were used to analyze the association. RESULTS: During a mean follow-up of 16.4 y until September 30, 2020, 442 thyroid cancer cases were identified. There was no significant association between total selenium intake and thyroid cancer risk after adjusting for multiple covariates (highest versus lowest quartile: hazard ratio [HR], 0.88; 95% confidence interval [CI], 0.60-1.29). Association between total selenium intake and the risk for papillary thyroid cancer was also not significant (highest versus lowest quartile: HR, 1.02; 95% CI, 0.66-1.52). CONCLUSIONS: The present data did not support that either total or dietary selenium intake was associated with the risk for thyroid cancer or the papillary subtype in postmenopausal women ages 50 to 79 y in the United States.

Association of omega-3 and omega-6 fatty acid intake with leukocyte telomere length in US males.

BACKGROUND: Omega-3 (n-3) and omega-6 (n-6) fatty acids may contribute to oxidative stress and inflammation, which are related to telomere shortening. Evidence supporting an association between intake of n-3 or n-6 fatty acids and leukocyte telomere length (LTL) in males has been limited. OBJECTIVES: We conducted a cross-sectional study to examine the associations of total or individual n-3 or total n-6 fatty acid intake with LTL in US males. METHODS: We included 2,494 US males with LTL measurement from 4 nested case-control studies within the Health Professionals Follow-Up Study. Individuals with previous histories of cancers, diabetes, and cardiovascular diseases at or before blood collection were excluded. Blood collection was performed between 1993 and 1995, and relevant information including n-3 and n-6 intake was collected in 1994 by questionnaire. The LTL was log-transformed and Z scores of the LTL were calculated for statistical analyses by standardizing the LTL in comparison with the mean within each selected nested case-control study. RESULTS: We found that consumption of DHA (22:6n-3) was positively associated with LTL. In the multivariable-adjusted model, compared with individuals who had the lowest intake of DHA (i.e., first quartile group), the percentage differences (95% CIs) of LTL were -3.7 (-13.7, 7.5), 7.0 (-4.3, 19.7), and 8.2 (-3.5, 21.3) for individuals in the second, third, and fourth quartiles of consumption, respectively (P-trend = 0.0498). We did not find significant associations between total n-3 or total n-6 fatty acid intakes and LTL. In addition, we found that males who consumed canned tuna had longer LTL than those who did not; in the multivariable-adjusted model, the percentage difference of LTL was 10.5 (95% CI: 1.3, 20.4) (P = 0.02). CONCLUSIONS: Our results suggest that higher intakes of DHA and canned tuna consumption are associated with longer LTL.

Recommendation on an updated standardization of serum magnesium reference ranges.

PURPOSE: Serum magnesium is the most frequently used laboratory test for evaluating clinical magnesium status. Hypomagnesemia (low magnesium status), which is associated with many chronic diseases, is diagnosed using the serum magnesium reference range. Currently, no international consensus for a magnesemia normal range exists. Two independent groups designated 0.85 mmol/L (2.07 mg/dL; 1.7 mEq/L) as the low cut-off point defining hypomagnesemia. MaGNet discussions revealed differences in serum magnesium reference ranges used by members' hospitals and laboratories, presenting an urgent need for standardization. METHODS: We gathered and compared serum magnesium reference range values from our institutions, hospitals, and colleagues worldwide. RESULTS: Serum magnesium levels designating "hypomagnesemia" differ widely. Of 43 collected values, only 2 met 0.85 mmol/L as the low cut-off point to define hypomagnesemia. The remainder had lower cut-off values, which may underestimate hypomagnesemia diagnosis in hospital, clinical, and research assessments. Current serum magnesium reference ranges stem from "normal" populations, which unknowingly include persons with chronic latent magnesium deficit (CLMD). Serum magnesium levels of patients with CLMD fall within widely used "normal" ranges, but their magnesium status is too low for long-term health. The lower serum magnesium reference (0.85 mmol/L) proposed specifically prevents the inclusion of patients with CLMD. CONCLUSIONS: Widely varying serum magnesium reference ranges render our use of this important medical tool imprecise, minimizing impacts of low magnesium status or hypomagnesemia as a marker of disease risk. To appropriately diagnose, increase awareness of, and manage magnesium status, it is critical to standardize lower reference values for serum magnesium at 0.85 mmol/L (2.07 mg/dL; 1.7 mEq/L).

Maternal electronic cigarette exposure in relation to offspring development: a comprehensive review.

Electronic cigarettes (e-cigarettes) have become increasingly popular in young generations in the United States. Because the adverse pregnancy outcomes associated with combustible cigarette smoking are well-recognized, many pregnant women switch to e-cigarettes believing that this alternative is low in toxic chemicals. However, most e-cigarettes contain nicotine, which can easily pass through the placenta and accumulate to a high concentration in fetal blood circulation. Studies have also detected toxic metals (eg, lead, cadmium, and nickel) in e-cigarettes, and carbonyl compounds and flavorings, which are suggested to be irritative and even carcinogenic. There are questions that need to be answered about the risks of e-cigarette exposure during pregnancy. Unfortunately, research evaluating the association between maternal e-cigarette exposure and offspring health is scarce, especially with regard to human studies. Some evidence from laboratory and animal studies, although inconsistent, showed that maternal exposure to e-cigarette vapor may lead to restricted growth of offspring. E-cigarette exposure may also have an impact on the metabolic health of offspring, manifested as distorted glucose homeostasis and energy metabolism. In addition, in utero exposure may lead to defects in respiratory, vascular, and neurologic system development. For humans, investigations mostly focused on immediate birth outcomes such as small-for-gestational-age neonates, low birthweight, and preterm birth; however, the results were inconclusive. Research also suggests that maternal e-cigarette exposure may result in compromised neurodevelopment in newborns. In summary, current evidence is insufficient to rigorously evaluate the health impacts of maternal e-cigarette use on offspring development. Future investigations are warranted.

Associations of cadmium exposure with risk of metabolic syndrome and its individual components: a meta-analysis.

Data directly associating cadmium (Cd) with metabolic syndrome (MetS) are sparse and inconsistent. We aimed to quantitatively assess the association of Cd exposure with risk of MetS and its individual components. Literature searching was performed in PubMed, EMBASE, and MEDLINE-OVID through September, 2021. Weighted odds ratios (ORs) for MetS and its components were pooled by comparing the highest to the lowest category of Cd exposure using random-effects models. Eleven (10 from Asia and 1 from the US) cross-sectional studies (33,887 participants and 7176 cases) were identified. Overall, Cd exposure was not associated with risk of MetS [OR: 1.08, 95% confidence interval (CI): 0.92, 1.28]. However, the association became significant when pooling Asian studies (OR: 1.18, 95% CI: 1.02, 1.35), and it was more pronounced with Cd measured in blood (OR: 1.24, 95% CI: 1.05, 1.45). Additionally, Cd exposure was significantly associated with reduced HDL-cholesterol (OR: 1.27, 95% CI: 1.05, 1.54) and elevated triglyceride (OR: 1.17, 95% CI: 1.05, 1.30), but not other components. This meta-analysis indicates that Cd exposure is associated with risk of MetS among Asian populations, which is mainly explained by Cd's association with dyslipidemia. Further studies are needed to better understand the mechanism of action.

Radon exposure and risk of cerebrovascular disease: a systematic review and meta-analysis in occupational and general population studies.

Although it is biologically plausible, findings relating radon exposure to the risk of cerebrovascular disease (CeVD) are inconsistent and inconclusive. To investigate whether radon exposure was associated with the risk of CeVD, we qualitatively and quantitatively summarized the literature on radon and CeVD in both occupational and general populations. A search of PubMed, Embase, Scopus, and Web of Science was performed for peer-reviewed articles published through March 2022. Studies were excluded if radon exposure was not assessed separately from other ionizing radiation. In the meta-analysis, excess relative risks (ERRs) were converted to relative risks (RRs), and the pooled RRs and 95% confidence intervals (CIs) were determined using the random-effects model (DerSimonian and Laird). In the systematic review, nine eligible studies were summarized. Six occupational studies indicated inconsistent associations between cumulative radon exposure and CeVD mortality among mine workers. With available data from four updated occupational studies (99,730 mine workers and 2745 deaths), the pooled RR of radon exposure with CeVD mortality showed a non-significant association (1.10, 95% CI 0.92, 1.31). Three studies (841,270 individuals and 24,288 events) conducted in general populations consistently demonstrated a significant inverse relationship between residential radon exposure and risk of CeVD. The existing literature suggested a potential link between radon exposure and CeVD risk in general population. The inconsistent association in occupationally exposed populations may be explained by different methods of radon assessment and other methodological issues. Since radon exposure is a common public health issue, more rigorously designed epidemiologic studies, especially in the general population are warranted.

Do B Vitamins Enhance the Effect of Omega-3 Polyunsaturated Fatty Acids on Cardiovascular Diseases? A Systematic Review of Clinical Trials.

Studies have suggested that B vitamins or omega-3 polyunsaturated fatty acids (PUFAs) may deter the development of cardiovascular disease (CVD). This systematic review aims to examine whether the combined supplementation of both B vitamins and omega-3 PUFAs could provide additional beneficial effects to prevent CVD beyond the effect of each supplement based on clinical trials published up to December 2021. The overall findings are inconsistent and inconclusive, yet the combined supplementation of these two nutrients may be more effective at reducing plasma homocysteine, triglyceride, and low-density lipoprotein-cholesterol than the individual components. The underlying mechanisms mainly include alleviating endothelial dysfunction, inhibiting atherosclerosis and lesion initiation, reducing oxidative stress, suppressing activation of pro-inflammatory cytokines, regulating endothelial nitric oxide synthase, and interfering with methylation of genes that promote atherogenesis. Although biologically plausible, the existing literature is insufficient to draw any firm conclusion regarding whether B vitamins can further enhance the potential beneficial effects of omega-3 PUFA intake on either primary or secondary prevention of CVD. The inconsistent findings may be largely explained by the methodological challenges. Therefore, well-designed high-quality trials that will use the combined supplementation of B vitamins and omega-3 PUFAs or dietary patterns rich in these two types of nutrients are warranted.

Does protracted radon exposure play a role in the development of dementia?

Radon is a ubiquitous radioactive gas that decays into a series of solid radioactive decay products. Radon, and its decay products, enter the human body primarily through inhalation and can be delivered to various tissues including the brain through systemic circulation. It can also reach the brain by neuronal pathways via the olfactory system. While ionizing radiation has been suggested as a risk factor of dementia for decades, studies exploring the possible role of radon exposure in the development of Alzheimer's Diseases (AD) and other dementias are sparse. We systematically reviewed the literature and found several lines of evidence suggesting that radon decay products (RDPs) disproportionally deposit in the brain of AD patients with selective accumulation within the protein fractions. Ecologic study findings also indicate a significant positive correlation between geographic-level radon distribution and AD mortality in the US. Additionally, pathologic studies of radon shed light on the potential pathways of radon decay product induced proinflammation and oxidative stress that may result in the development of dementia. In summary, there are plausible underlying biological mechanisms linking radon exposure to the risk of dementia. Since randomized clinical trials on radon exposure are not feasible, well-designed individual-level epidemiologic studies are urgently needed to elucidate the possible association between radon (i.e., RDPs) exposure and the onset of dementia.

B vitamin intakes modify the association between particulate air pollutants and incidence of all-cause dementia: Findings from the Women's Health Initiative Memory Study.

INTRODUCTION: Particulate air pollutants may induce neurotoxicity by increasing homocysteine levels, which can be lowered by high B vitamin intakes. Therefore, we examined whether intakes of three B vitamins (folate, B12 , and B6 ) modified the association between PM2.5 exposure and incidence of all-cause dementia. METHODS: This study included 7183 women aged 65 to 80 years at baseline. B vitamin intakes from diet and supplements were estimated by food frequency questionnaires at baseline. The 3-year average PM2.5 exposure was estimated using a spatiotemporal model. RESULTS: During a mean follow-up of 9 years, 342 participants developed all-cause dementia. We found that residing in locations with PM2.5 exposure above the regulatory standard (12 µg/m3 ) was associated with a higher risk of dementia only among participants with lower intakes of these B vitamins. DISCUSSION: This is the first study suggesting that the putative neurotoxicity of PM2.5 exposure may be attenuated by high B vitamin intakes.

Cadmium Exposure in Young Adulthood Is Associated with Risk of Nonalcoholic Fatty Liver Disease in Midlife.

BACKGROUND: Studies have suggested that cadmium (Cd) may be involved in the etiology of nonalcoholic fatty liver disease (NAFLD), but available data in human is sparse. AIMS: We aimed to examine Cd exposure in young adulthood in relation to prevalent NAFLD in midlife among American adults. METHODS: This study included 2446 participants from the Coronary Artery Risk Development in Young Adults study with toenail Cd measurement at exam year 2 (baseline) and computed tomography quantification of liver fat at exam year 25. Toenail Cd concentrations were considered as a reliable marker of long-term exposure. NAFLD was defined if liver attenuation < 51 Hounsfield units after excluding other possible causes of liver fat. Multivariable-adjusted logistic regression models were used to estimate the odds ratio of NAFLD by Cd exposure. RESULTS: Median toenail Cd concentration was 8.2 ppb (inter-quartile range 4.3-18.6 ppb). After 23 years from baseline, 580 participants with prevalent NAFLD (24% prevalence) in midlife were identified. Compared with individuals in the lowest quartile, those in the highest quartile of toenail Cd had a significantly higher odds of NAFLD (OR: 1.43, 95% CI: 1.02, 1.99, P for trend: 0.04) after adjustment for demographics, socioeconomics, major lifestyle factors, and baseline levels of body mass index, lipids, and fasting insulin. The association was not significantly modified by race, sex, BMI, or smoking status at baseline. CONCLUSIONS: Toenail Cd concentration was associated with a higher odds of prevalent NAFLD23 years later in life in this cohort of US general population.