Association between blood metals mixtures concentrations and cognitive performance, and effect modification by diet in older US adults

Associations of a toenail metal mixture with attention and memory in the Gulf long-term follow-up (GuLF) study

BACKGROUND

Research on metal-associated neurodegeneration has largely focused on single metals. Since metal exposures typically co-occur as combinations of both toxic and essential elements, a mixtures framework is important for identifying risk and protective factors. This study examined associations between toenail levels of an eight-metal mixture and attention and memory in men living in US Gulf states.

METHODS

We measured toenail concentrations of toxic (arsenic, chromium, lead, and mercury) and essential (copper, manganese, selenium, and zinc) metals in 413 non-smoking men (23-69 years, 46 % Black) from the Gulf Long-Term Follow-Up (GuLF) Study. Sustained attention and working memory were assessed at the time of toenail sample collection using the continuous performance test (CPT) and digit span test (DST), respectively. Associations between toenail metal concentrations and performance on neurobehavioral tests were characterized using co-pollutant adjusted general linear models and Bayesian Kernel Machine Regression.

RESULTS

Adjusting for other metals, one interquartile range (IQR) increase in toenail chromium was associated with a 0.19 (95 % CI: -0.31, -0.07) point reduction in CPT D Prime score (poorer ability to discriminate test signals from noise). One IQR increase in toenail manganese was associated with a 0.20 (95 % CI, -0.41, 0.01) point reduction on the DST Reverse Count (fewer numbers recalled). Attention deficits were greater among Black participants compared to White participants for the same increase in toenail chromium concentrations. No evidence of synergistic interaction between metals or adverse effect of the overall metal mixture was observed for either outcome.

CONCLUSIONS

Our findings support existing studies of manganese-related memory deficits and are some of the first to show chromium related attention deficits in adults. Longitudinal study of cognitive decline is needed to verify chromium findings. Research into social and chemical co-exposures is also needed to explain racial differences in metal-associated neurobehavioral deficits observed in this study.

Joint effects between cadmium exposure and dietary antioxidant quality score on osteoporosis and bone mineral density

To explore the relationship between dietary antioxidant quality score (DAQS) and Cd exposure both alone and in combination with osteoporosis and bone mineral density (BMD) among postmenopausal women. In total, 4920 postmenopausal women from the National Health and Nutrition Examination Survey were included in this cross-sectional study. Weighted univariate and multivariate logistic regression analyses to assess the association between DAQS and Cd exposure with femur neck BMD, total femur BMD, osteoporosis among postmenopausal women, respectively, and the coexistence effect of DAQS and Cd exposure. Four hundred and ninety-nine had osteoporosis. DAQS (OR = 0·86, 95 % CI 0·77, 0·97) and high DAQS (OR = 0·60, 95 % CI 0·36, 0·99) were found to be associated with decreased odds of osteoporosis, while Cd exposure (OR = 1·34, 95 % CI 1·04, 1·72) and high Cd exposure (OR = 1·45, 95 % CI 1·02, 2·06) were related to increased odds of osteoporosis. A positive correlation was observed between high DAQS and both total femur BMD and femur neck BMD. Conversely, Cd exposure was found to be negatively correlated with total femur BMD and femur neck BMD. Additionally, taking low-Cd and high-quality DAQS group as reference, the joint effect of Cd exposure and DAQS showed greater increased odds of osteoporosis and decreased total femur BMD and femur neck BMD as Cd level and DAQS combinations worsened. There may be an interaction between Cd exposure and DAQS for femur neck BMD, total femur BMD, and osteoporosis in postmenopausal women.

Periconceptional diet quality and its relation to blood heavy metal concentrations among pregnant women: The Japan environment and Children's study

BACKGROUND

Diets contain toxic chemical contaminants as well as essential nutrients, both of which influence the intrauterine environment for foetal growth. However, whether a high-quality diet that is nutritionally healthy also results in lower exposure to chemical contaminants is unknown.

OBJECTIVE

We examined associations between periconceptional maternal diet quality and circulating concentrations of heavy metals during pregnancy.

DESIGN

Dietary intake over the year prior to the first trimester of pregnancy was assessed using a validated, self-administered food frequency questionnaire among 81,104 pregnant Japanese women who participated in the Japan Environment and Children's Study. Overall diet quality was determined using the Balanced Diet Score (BDS) based on the Japanese Food Guide Spinning Top, the Healthy Eating Index-2015 (HEI-2015), the Dietary Approaches to Stop Hypertension (DASH) score and the Mediterranean diet score (MDS). We measured whole-blood concentrations of mercury (Hg), lead (Pb) and cadmium (Cd) during the second or third trimester of pregnancy.

RESULTS

After controlling for confounders, all diet quality scores were positively associated with blood Hg concentrations. By contrast, higher BDS, HEI-2015 and DASH scores were associated with lower concentrations of Pb and Cd. Although the MDS was positively associated with concentrations of Pb and Cd, when dairy products were classified as a beneficial (rather than detrimental) food component, these associations were attenuated.

CONCLUSION

A high-quality diet may reduce exposure to Pb and Cd but not Hg. Further studies are required to determine the optimal balance between mercury exposure risk and nutritional benefits of high-quality diets prior to pregnancy.

Periconceptional maternal diet quality influences blood heavy metal concentrations and their effect on low birth weight: the Japan Environment and Children's Study

BACKGROUND

Both poor maternal nutrition and toxic heavy metal exposure influence foetal growth and development. However, whether consumption of a variety of healthy foods modifies the association between prenatal heavy metal exposure and foetal growth is unknown.

OBJECTIVE

We examined whether long-term maternal diet quality in periconception modifies the associations between maternal circulating concentrations of heavy metals and foetal growth.

DESIGN

Data of 72,317 Japanese women who delivered singleton infants was extracted from the Japan Environment and Children's Study. Maternal diet over a 1-year before the first trimester of pregnancy was assessed using a validated food frequency questionnaire, and overall diet quality was determined using the balanced diet score based on the Japanese Food Guide Spinning Top. Maternal whole-blood concentrations of mercury (Hg), lead (Pb) and cadmium (Cd) were measured during the second/third trimester of pregnancy. Bayesian inference of multiple linear regression analysis was performed to evaluate the relationships between maternal diet quality and the blood concentrations of heavy metals; Bayesian logistic regression was used to analyse the risk of low birth weight (LBW; <2,500 g).

RESULTS

After controlling for confounders, a high maternal balanced diet score was associated with low concentrations of blood Pb and Cd and high Hg. While all heavy metals assessed were positively associated with LBW risk, a higher maternal balanced diet score was negatively associated with LBW risk. A high-quality maternal diet attenuated the effect of Pb on LBW, an effect that was more marked at high blood Pb concentrations.

CONCLUSION

A high-quality, 'well-balanced' diet prior to conception may reduce exposure to some heavy metals and mitigate the elevated risk of LBW associated with prenatal Pb exposure in Japanese mother-child pairs.

Single and Combined Associations of Plasma and Urine Essential Trace Elements (Zn, Cu, Se, and Mn) with Cardiovascular Risk Factors in a Mediterranean Population

Trace elements are micronutrients that are required in very small quantities through diet but are crucial for the prevention of acute and chronic diseases. Despite the fact that initial studies demonstrated inverse associations between some of the most important essential trace elements (Zn, Cu, Se, and Mn) and cardiovascular disease, several recent studies have reported a direct association with cardiovascular risk factors due to the fact that these elements can act as both antioxidants and pro-oxidants, depending on several factors. This study aims to investigate the association between plasma and urine concentrations of trace elements and cardiovascular risk factors in a general population from the Mediterranean region, including 484 men and women aged 18−80 years and considering trace elements individually and as joint exposure. Zn, Cu, Se, and Mn were determined in plasma and urine using an inductively coupled plasma mass spectrometer (ICP-MS). Single and combined analysis of trace elements with plasma lipid, blood pressure, diabetes, and anthropometric variables was undertaken. Principal component analysis, quantile-based g-computation, and calculation of trace element risk scores (TERS) were used for the combined analyses. Models were adjusted for covariates. In single trace element models, we found statistically significant associations between plasma Se and increased total cholesterol and systolic blood pressure; plasma Cu and increased triglycerides and body mass index; and urine Zn and increased glucose. Moreover, in the joint exposure analysis using quantile g-computation and TERS, the combined plasma levels of Zn, Cu, Se (directly), and Mn (inversely) were strongly associated with hypercholesterolemia (OR: 2.03; 95%CI: 1.37−2.99; p < 0.001 per quartile increase in the g-computation approach). The analysis of urine mixtures revealed a significant relationship with both fasting glucose and diabetes (OR: 1.91; 95%CI: 1.01−3.04; p = 0.046). In conclusion, in this Mediterranean population, the combined effect of higher plasma trace element levels (primarily Se, Cu, and Zn) was directly associated with elevated plasma lipids, whereas the mixture effect in urine was primarily associated with plasma glucose. Both parameters are relevant cardiovascular risk factors, and increased trace element exposures should be considered with caution.

Potential benefits of joint hypothetical interventions on diet, lead, and cadmium on mortality in US adults

BACKGROUND

Previous studies reported associations between high blood lead levels (BLLs) and urinary cadmium (UCd) concentrations and all-cause and cause-specific mortality. It is hypothesized that these associations are mediated by inflammation; therefore, adherence to an anti-inflammatory diet may mitigate these effects. We sought to estimate the potential effects of joint hypothetical interventions on metals levels and adherence to an anti-inflammatory diet or fruits and vegetables (FV) intake on the expected mortality distributions.

METHODS

We used data on 14,311 adults aged ≥ 20 years enrolled in the NHANES-III between 1988 and 1994 and followed up through Dec 31, 2015. We estimated daily FV servings and adherence to the dietary inflammatory index at baseline using 24-hour dietary recalls. Mortality was determined from the National Death Index records. We used the parametric g-formula with pooled logistic regression models to estimate the absolute risk of all-cause, cardiovascular, and cancer mortality under different hypothetical interventions compared to the natural course (no intervention).

RESULTS

Overall, we observed a decreased mortality risk when intervening to lower metals levels or increasing adherence to an anti-inflammatory diet or the daily FV servings. The joint intervention to lower BLLs and UCd and increase the adherence to the anti-inflammatory diet had the strongest impact on cancer mortality risk (risk difference [RD] = -1.50% (-2.52% to -0.62%)) compared to the joint intervention only on metals levels RD= -0.97% (-1.89 to 0.70). The same pattern of associations was observed for the joint intervention to lower both metals and increased daily FV servings and cardiovascular diseases mortality risk.

CONCLUSION

Higher diet quality may constitute a complementary approach to the interventions to reduce exposures to cadmium and lead to further minimize their effects on mortality. A paradigm shift is required from a pollutant-focused only to a combination with a human-focused approach for primary prevention against these metals.

Relationships between urinary metals concentrations and cognitive performance among U.S. older people in NHANES 2011-2014

Background

Epidemiological evidence on Urine metals and cognitive impairment in older individuals is sparse and limited. The goal of this study was to analyze if there was a link between urinary metal levels and cognitive performance in U.S. people aged 60 and up.

Methods

The National Health and Nutrition Examination Survey (NHANES) data from 2011 to 2014 were utilized in this cross-sectional analysis. Memory function was quantified using the following methods: Established Consortium for Word Learning in Alzheimer's Disease (CERAD-WL) (immediate learning and recall and delayed recall), Animal Fluency Test (AFT), and Digit Symbol Substitution Test (DSST). An inductively coupled plasma mass spectrometry (ICP-MS) was used to estimate urine metal concentrations. The connection of Urine metals level with cognitive function was investigated employing binary logistic regression and restricted cubic spline models.

Results

A total of 840 participants aged 60 years and over were enrolled in this study. After controlling for confounders, the association between cadmium, barium, cobalt, cesium, manganese, and thallium and poor cognitive performance showed significance in multiple logistic regression compared to the lowest quartile of metals. In the DSST test, the weighted multivariate adjusted ORs (95% CI) for cadmium in the highest quartile, barium and cesium in the third quartile were 2.444 (1.310-4.560), 0.412 (0.180-0.942) and 0.440 (0.198-0.979), respectively. There were L-shaped associations between urine cesium, barium, or manganese and low cognitive performance in DSST. Urine lead, molybdenum and uranium did not show any significant relationships with cognitive impairment, respectively, compared to the respective lowest quartile concentrations.

Conclusion

The levels of barium (Ba), cobalt (Co), cesium (Cs), manganese (Mn), and thallium (Tl) in urine were found to be negatively related to the prevalence of impaired cognitive performance in our cross-sectional investigation. Higher cadmium (Cd) levels were associated with cognitive impairment.