Circulating plasma phospholipid fatty acid levels as a biomarker of habitual dietary fat intake: The INTERMAP/INTERLIPID Study.

BACKGROUND: Accurate assessment of fat intake is essential to examine relationships between diet and disease risk. However, estimating individual intakes of fat quantity by dietary assessment is difficult. OBJECTIVE: We assessed the association of plasma phospholipid fatty acid levels with dietary intake of fatty acids in the INTERMAP/INTERLIPID study, conducted with a standardized protocol. METHODS: The study participants were 1339 men and women ages 40-59 years from five Japanese populations one from Hawaii; four from Japan. Fatty acid intake was estimated from four standardized 24-hour dietary recalls. Plasma phospholipid fatty acid composition was analyzed by gas chromatography. We illustrated the relationship between intake and circulating fatty acid levels using Spearman's rank-correlation coefficients, mean, and median values. RESULTS: Spearman's rank-correlation coefficients between intake (g/d) and circulating fatty acid levels (µg/ml) were -0.03 to 0.21 for saturated fatty acids and monounsaturated fatty acids and -0.04 to 0.32 for trans fatty acids. The coefficients for essential n-3 and n-6 fatty acids were moderate to high, especially for eicosapentaenoic acid (EPA), 0.60; docosahexaenoic acid (DHA), 0.41; and EPA+DHA, 0.51. The circulating levels and intake of marine-derived n-3 fatty acids showed a linear association, at least for the intake of EPA+DHA up to 2.1 g/d. CONCLUSION: We observed high correlation between intake and circulating levels of marine-derived n-3 fatty acids in participants from Japanese and Japanese-American populations with high and low fish intake. Plasma phospholipid marine-derived n-3 fatty acid measurements are a simple and reliable biomarker for assessing dietary intake.

Investigation of the urinary sodium-to-potassium ratio target level based on the recommended dietary intake goals for the Japanese population: The INTERMAP Japan.

Growing epidemiological evidence has shown an association of the urinary sodium (Na) to potassium (K) ratio (Na/K ratio) with blood pressure and cardiovascular diseases. However, no clear cutoff level has been defined. We investigated the cutoff level of the urinary Na/K ratio under different dietary guidelines for Japanese individuals, especially that endorsed by the 2020 revised Japanese Dietary Reference Intakes (DRIs). A population of 1145 Japanese men and women aged 40 to 59 years from the INTERMAP study was examined. Using high-quality standardized data, the averages of two 24 h urinary collections and four 24 h dietary recalls were used to calculate the 24 h urinary and dietary Na/K ratios, respectively. Associations between the urinary and dietary Na/K ratios were tested by sex- and age-adjusted partial correlation. The optimal urinary Na/K ratio cutoff level was determined by receiver operating characteristic (ROC) curves and sex-specific cross tables for recommended dietary K and salt. Overall, the average molar ratio of 24 h urinary Na/K was 4.3. We found moderate correlations (P < 0.001) of the 24 h urinary Na/K ratio with 24 h urinary Na and K excretion (r = 0.52, r = -0.49, respectively) and the dietary Na/K ratio (r = 0.53). ROC curves showed that a 24 h urinary Na/K ratio of approximately 2 predicted Na and K intake that meets the dietary goals of the Japanese DRIs. The range of urinary Na/K ratios meeting the dietary goals of the Japanese DRIs for both Na and K was 1.6‒2.2 for men and 1.7‒1.9 for women. Accomplishing a urinary Na/K ratio of 2 would be desirable to achieve the DRIs dietary goals for both Na and K simultaneously in middle-aged Japanese men and women accustomed to Japanese dietary habits. This observational study is registered at www.clinicaltrials.gov as NCT00005271.

Blood pressure interactions with the DASH dietary pattern, sodium, and potassium: The International Study of Macro-/Micronutrients and Blood Pressure (INTERMAP).

BACKGROUND: Adherence to the Dietary Approaches to Stop Hypertension (DASH) diet enhances potassium intake and reduces sodium intake and blood pressure (BP), but the underlying metabolic pathways are unclear. OBJECTIVES: Among free-living populations, we delineated metabolic signatures associated with the DASH diet adherence, 24-hour urinary sodium and potassium excretions, and the potential metabolic pathways involved. METHODS: We used 24-hour urinary metabolic profiling by proton nuclear magnetic resonance spectroscopy to characterize the metabolic signatures associated with the DASH dietary pattern score (DASH score) and 24-hour excretion of sodium and potassium among participants in the United States (n = 2164) and United Kingdom (n = 496) enrolled in the International Study of Macro- and Micronutrients and Blood Pressure (INTERMAP). Multiple linear regression and cross-tabulation analyses were used to investigate the DASH-BP relation and its modulation by sodium and potassium. Potential pathways associated with DASH adherence, sodium and potassium excretion, and BP were identified using mediation analyses and metabolic reaction networks. RESULTS: Adherence to the DASH diet was associated with urinary potassium excretion (correlation coefficient, r = 0.42; P < 0.0001). In multivariable regression analyses, a 5-point higher DASH score (range, 7 to 35) was associated with a lower systolic BP by 1.35 mmHg (95% CI, -1.95 to -0.80 mmHg; P = 1.2 × 10-5); control of the model for potassium but not sodium attenuated the DASH-BP relation. Two common metabolites (hippurate and citrate) mediated the potassium-BP and DASH-BP relationships, while 5 metabolites (succinate, alanine, S-methyl cysteine sulfoxide, 4-hydroxyhippurate, and phenylacetylglutamine) were found to be specific to the DASH-BP relation. CONCLUSIONS: Greater adherence to the DASH diet is associated with lower BP and higher potassium intake across levels of sodium intake. The DASH diet recommends greater intake of fruits, vegetables, and other potassium-rich foods that may replace sodium-rich processed foods and thereby influence BP through overlapping metabolic pathways. Possible DASH-specific pathways are speculated but confirmation requires further study. INTERMAP is registered as NCT00005271 at www.clinicaltrials.gov.

Association between egg intake and blood pressure in the USA: the INTERnational study on MAcro/micronutrients and blood Pressure (INTERMAP).

OBJECTIVES: To investigate associations of egg intake with blood pressure (BP) and the role of dietary variables and other macro- and micro-nutrients in the association. DESIGN: We used cross-sectional data for the USA as part of the INTERnational study on MAcro/micronutrients and blood Pressure (INTERMAP). INTERMAP was surveyed between 1996 and 1999, including four 24-h dietary recalls, two 24-h urine collections and eight measurements of systolic BP and diastolic BP (SBP, DBP). Average egg intake (g/d) was calculated. Multivariable linear regression models were used to estimate the association between egg intake (per each 50 g/d or per quintile) and BP. The roles of dietary variables and other macro- and micro-nutrients in this association were also investigated. SETTING: In the USA. PARTICIPANTS: In total, 2195 US INTERMAP men and women aged 40-59 years. RESULTS: Participants were 50 % female, 54 % non-Hispanic White and 16 % non-Hispanic Black. Mean egg intake (sd) in men and women was 30·4(29·8) and 21·6(20·5) g/d, respectively. Adjusting for demographics, socio-economics, lifestyle and urinary Na:K excretion ratios, we found non-linear associations with BP in non-obese women (P-quadratic terms: 0·004 for SBP and 0·035 for DBP).The associations remained after adjusting for dietary variables, macro/micro nutrients or minerals. Dietary cholesterol was highly correlated with egg intake and may factor in the association. No association was found in obese women and in obese or non-obese men. CONCLUSION: Egg intake was non-linearly associated with SBP and DBP in non-obese women, but not in obese women or men. Underlying mechanisms require additional study regarding the role of obesity and sex.

Relationships of Alcohol Consumption with Coronary Risk Factors and Macro- and Micro-Nutrient Intake in Japanese People: The INTERLIPID Study.

Several studies have reported a J-shaped relationship between alcohol consumption and coronary heart disease (CHD) risk. However, the mechanisms of this relationship remain unclear. This study aimed to evaluate the relationships of alcohol consumption with established CHD risk factors and with macro-/micro-nutrient intake among Japanese people. Participants were 1,090 Japanese men and women aged 40-59 y enrolled in the INTERLIPID study, excluding former drinkers. Based on two 7-d alcohol records, participants were classified as non-drinkers (0 g/wk), light-drinkers (<100 g/wk), moderate-drinkers (100-299 g/wk), or heavy-drinkers (≥300 g/wk). Detailed macro-/micro-nutrient intake was evaluated using four in-depth 24-h dietary recalls and adjusted for total energy intake excluding alcohol. We analyzed the associations of CHD risk factors and nutrient intake with alcohol consumption. Serum high-density lipoprotein cholesterol and blood pressure were higher and low-density lipoprotein cholesterol was lower among those with higher alcohol consumption. J-shaped relationships with alcohol consumption were observed for the proportion of current smokers, number of cigarettes smoked, and prevalence of hypertension; these risk factors were lowest among light-drinkers. Carbohydrate and total fiber intakes were lower and protein and dietary cholesterol intakes were higher among those with higher alcohol consumption. These associations were similar for men and women. Alcohol consumption was related to nutrient intake as well as established CHD risk factors. Non-drinkers were higher on some CHD risk factors than were light-drinkers. These findings may influence the J-shaped relationship between alcohol consumption and CHD risk.

Strategy for improved characterization of human metabolic phenotypes using a COmbined Multi-block Principal components Analysis with Statistical Spectroscopy (COMPASS).

MOTIVATION: Large-scale population omics data can provide insight into associations between gene-environment interactions and disease. However, existing dimension reduction modelling techniques are often inefficient for extracting detailed information from these complex datasets. RESULTS: Here, we present an interactive software pipeline for exploratory analyses of population-based nuclear magnetic resonance spectral data using a COmbined Multi-block Principal components Analysis with Statistical Spectroscopy (COMPASS) within the R-library hastaLaVista framework. Principal component analysis models are generated for a sequential series of spectral regions (blocks) to provide more granular detail defining sub-populations within the dataset. Molecular identification of key differentiating signals is subsequently achieved by implementing Statistical TOtal Correlation SpectroscopY on the full spectral data to define feature patterns. Finally, the distributions of cross-correlation of the reference patterns across the spectral dataset are used to provide population statistics for identifying underlying features arising from drug intake, latent diseases and diet. The COMPASS method thus provides an efficient semi-automated approach for screening population datasets. AVAILABILITY AND IMPLEMENTATION: Source code is available at https://github.com/cheminfo/COMPASS. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Nutriome-metabolome relationships provide insights into dietary intake and metabolism.

Dietary assessment traditionally relies on self-reported data which are often inaccurate and may result in erroneous diet-disease risk associations. We illustrate how urinary metabolic phenotyping can be used as alternative approach for obtaining information on dietary patterns. We used two multi-pass 24-hr dietary recalls, obtained on two occasions on average three weeks apart, paired with two 24-hr urine collections from 1,848 U.S. individuals; 67 nutrients influenced the urinary metabotype measured with 1H-NMR spectroscopy characterized by 46 structurally identified metabolites. We investigated the stability of each metabolite over time and showed that the urinary metabolic profile is more stable within individuals than reported dietary patterns. The 46 metabolites accurately predicted healthy and unhealthy dietary patterns in a free-living U.S. cohort and replicated in an independent U.K. cohort. We mapped these metabolites into a host-microbial metabolic network to identify key pathways and functions. These data can be used in future studies to evaluate how this set of diet-derived, stable, measurable bioanalytical markers are associated with disease risk. This knowledge may give new insights into biological pathways that characterize the shift from a healthy to unhealthy metabolic phenotype and hence give entry points for prevention and intervention strategies.

Identifying unknown metabolites using NMR-based metabolic profiling techniques.

Metabolic profiling of biological samples provides important insights into multiple physiological and pathological processes but is hindered by a lack of automated annotation and standardized methods for structure elucidation of candidate disease biomarkers. Here we describe a system for identifying molecular species derived from nuclear magnetic resonance (NMR) spectroscopy-based metabolic phenotyping studies, with detailed information on sample preparation, data acquisition and data modeling. We provide eight different modular workflows to be followed in a recommended sequential order according to their level of difficulty. This multi-platform system involves the use of statistical spectroscopic tools such as Statistical Total Correlation Spectroscopy (STOCSY), Subset Optimization by Reference Matching (STORM) and Resolution-Enhanced (RED)-STORM to identify other signals in the NMR spectra relating to the same molecule. It also uses two-dimensional NMR spectroscopic analysis, separation and pre-concentration techniques, multiple hyphenated analytical platforms and data extraction from existing databases. The complete system, using all eight workflows, would take up to a month, as it includes multi-dimensional NMR experiments that require prolonged experiment times. However, easier identification cases using fewer steps would take 2 or 3 days. This approach to biomarker discovery is efficient and cost-effective and offers increased chemical space coverage of the metabolome, resulting in faster and more accurate assignment of NMR-generated biomarkers arising from metabolic phenotyping studies. It requires a basic understanding of MATLAB to use the statistical spectroscopic tools and analytical skills to perform solid phase extraction (SPE), liquid chromatography (LC) fraction collection, LC-NMR-mass spectroscopy and one-dimensional and two-dimensional NMR experiments.

Food Sources of Dietary Potassium in the Adult Japanese Population: The International Study of Macro-/Micronutrients and Blood Pressure (INTERMAP).

A lower-than-recommended potassium intake is a well-established risk factor for increased blood pressure. Although the Japanese diet is associated with higher sodium intake and lower potassium intake, few studies have examined the source foods quantitatively. Studies on dietary patterns in association with potassium intake will be useful to provide dietary advice to increase potassium intake. Twenty-four-hour (hr) dietary recall data and 24-hr urinary potassium excretion data from Japanese participants (574 men and 571 women) in the International Study of Macro/Micronutrients and Blood Pressure (INTERMAP) were used to calculate food sources of potassium and compare food consumption patterns among quartiles of participants categorized according to 24-hr urinary potassium excretion per unit of body weight (UK/BW). The average potassium intake was 2791 mg/day per participant, and the major sources were vegetables and fruits (1262 mg/day), fish (333 mg/day), coffee and tea (206 mg/day), and milk and dairy products (200 mg/day). Participants in the higher UK/BW quartile consumed significantly more vegetables and fruits, fish, and milk and dairy products, and ate less rice and noodles. Conclusion: Advice to increase the intake of vegetables and fruits, fish, and milk may be useful to increase potassium intake in Japan.

Potato consumption, by preparation method and meal quality, with blood pressure and body mass index: The INTERMAP study.

BACKGROUND AND AIMS: Previous studies have reported associations between higher potato intake and higher blood pressure (BP) and/or risk of hypertension and obesity. These studies rarely considered preparation methods of potatoes, overall dietary pattern or the nutrient quality of the meals. These factors may affect the association of potato intake with BP and body mass index (BMI). This study investigated potato consumption by amount, type of processing, overall dietary pattern, and nutrient quality of the meals in relation to BP and BMI. METHODS: Cross-sectional analyses were conducted among 2696 participants aged 40-59 y in the US and UK samples of the International Study of Macro- and Micro-Nutrients and Blood Pressure (INTERMAP). Nutrient quality of individual food items and the overall diet was assessed with the Nutrient-Rich Foods (NRF) index. RESULTS: No associations with BP or BMI were found for total potato intake nor for boiled, mashed, or baked potatoes or potato-based mixed dishes. In US women, higher intake of fried potato was associated with 2.29 mmHg (95% CI: 0.55, 3.83) higher systolic BP and with 1.14 mmHg (95% CI: 0.10, 2.17) higher diastolic BP, independent of BMI. Higher fried potato consumption was directly associated with a +0.86 kg/m2 difference in BMI (95% CI: 0.24, 1.58) in US women. These associations were not found in men. Higher intakes of fried potato meals with a lower nutritional quality (NRF index≤ 2) were positively associated with systolic (3.88 mmHg; 95% CI: 2.63, 5.53) and diastolic BP (1.62 mmHg; 95% CI: 0.48, 2.95) in US women. No associations with BP were observed for fried potato meals with a higher nutritional quality (NRF index> 2). CONCLUSIONS: Fried potato was directly related to BP and BMI in women, but non-fried potato was not. Poor-nutrient quality meals were associated with intake of fried potatoes and higher BP, suggesting that accompanied dietary choices are key mediators of these associations.

Association between plant-based diets and blood pressure in the INTERMAP study.

BACKGROUND: Plant-based diets are associated with a lower risk of cardiovascular diseases; however, little is known how the healthiness of the diet may be associated with blood pressure (BP). We aimed to modify three plant -based diet indices: overall plant-based diet index (PDI), healthy PDI (hPDI), and unhealthy PDI (uPDI) according to country-specific dietary guidelines to enable use across populations with diverse dietary patterns - and assessed their associations with BP. DESIGN: We used cross-sectional data including 4,680 men and women ages 40-59y in Japan, China, the United Kingdom, and the United States from the INTERnational study on MAcro/micronutrients and blood Pressure (INTERMAP). During four visits, eight BP measurements, and four 24-h dietary recalls were collected. Multivariable regression coefficients were estimated, pooled, weighted, and adjusted extensively for lifestyle/dietary confounders. RESULTS: Modified PDI was not associated with BP. Consumption of hPDI higher by 1SD was inversely associated with systolic (-0.82 mm Hg;95% CI:-1.32,-0.49) and diastolic BP (-0.49 mm Hg; 95% CI:-0.91, -0.28). In contrast, consumption of an uPDI was directly associated with systolic (0.77 mm Hg;95% CI:0.30,1.20). Significant associations between hPDI with BP were attenuated with separate adjustment for vegetables and whole grains; associations between uPDI and BP were attenuated after adjustment for refined grains, sugar-sweetened beverages, and meat. CONCLUSION: An hPDI is associated with lower BP while a uPDI is adversely related to BP. Plant-based diets rich in vegetables and whole grains and limited in refined grains, sugar-sweetened beverages, and total meat may contribute to these associations. In addition to current guidelines, the nutritional quality of consumed plant foods is as important as limiting animal-based components. TRIAL REGISTRATION NUMBER: The observational INTERMAP study was registered at www.clinicaltrials.gov as NCT00005271.

The Association Between Family Social Network Size and Healthy Lifestyle Factors: Results from the Hispanic Community Health Study/Study of Latinos (HCHS/SOL).

We examined associations of central family (i.e., children, parents, in-laws) social network size with healthy lifestyle factors (i.e., favorable body mass index, physical activity, diet, alcohol use, smoking). Using data on 15,511 Hispanics/Latinos 18-74 years old from the Hispanic Community Health Study/Study of Latinos, multivariable adjusted survey logistic regression was used to compute associations of social network size with healthy lifestyle factors. A one-unit higher total of central family size was associated with lower odds of healthy body mass index (OR 0.90; 95% CI 0.86-0.93) and having all five healthy lifestyle factors (OR 0.90; 95% CI 0.85-0.96). Findings suggest familial structural social support may contribute to healthy lifestyle factors and differ based on the type of relationship among Hispanics/Latinos.

The association of fish consumption and its urinary metabolites with cardiovascular risk factors: the International Study of Macro-/Micronutrients and Blood Pressure (INTERMAP).

BACKGROUND: Results from observational studies regarding associations between fish (including shellfish) intake and cardiovascular disease risk factors, including blood pressure (BP) and BMI, are inconsistent. OBJECTIVE: To investigate associations of fish consumption and associated urinary metabolites with BP and BMI in free-living populations. METHODS: We used cross-sectional data from the International Study of Macro-/Micronutrients and Blood Pressure (INTERMAP), including 4680 men and women (40-59 y) from Japan, China, the United Kingdom, and United States. Dietary intakes were assessed by four 24-h dietary recalls and BP from 8 measurements. Urinary metabolites (2 timed 24-h urinary samples) associated with fish intake acquired from NMR spectroscopy were identified. Linear models were used to estimate BP and BMI differences across categories of intake and per 2 SD higher intake of fish and its biomarkers. RESULTS: No significant associations were observed between fish intake and BP. There was a direct association with fish intake and BMI in the Japanese population sample (P trend = 0.03; fully adjusted model). In Japan, trimethylamine-N-oxide (TMAO) and taurine, respectively, demonstrated area under the receiver operating characteristic curve (AUC) values of 0.81 and 0.78 in discriminating high against low fish intake, whereas homarine (a metabolite found in shellfish muscle) demonstrated an AUC of 0.80 for high/nonshellfish intake. Direct associations were observed between urinary TMAO and BMI for all regions except Japan (P < 0.0001) and in Western populations between TMAO and BP (diastolic blood pressure: mean difference 1.28; 95% CI: 0.55, 2.02 mmHg; P = 0.0006, systolic blood pressure: mean difference 1.67; 95% CI: 0.60, 2.73 mmHg; P = 0.002). CONCLUSIONS: Urinary TMAO showed a stronger association with fish intake in the Japanese compared with the Western population sample. Urinary TMAO was directly associated with BP in the Western but not the Japanese population sample. Associations between fish intake and its biomarkers and downstream associations with BP/BMI appear to be context specific. INTERMAP is registered at www.clinicaltrials.gov as NCT00005271.

The MMPI factor scales and risk of death in men during 45 years of follow-up: The Western Electric study.

We examined associations between personality traits measured in 1958 and both all-cause and cause-specific mortality assessed 45 years later in 2003. Participants were 1,862 middle-aged men employed by the Western Electric Company. Outcomes were days to death from all causes, coronary heart disease, stroke, cancer, and causes other than circulatory diseases, cancer, accidents/homicide/suicides, or injuries (other causes). Measures in 1958 included age, education, health behaviors, biomedical risk factors, and nine content factors identified in the Minnesota Multiphasic Personality Inventory (MMPI). Four content factors-neuroticism, cynicism, extraversion, and intellectual interests-were related to the five-factor model domains of neuroticism, agreeableness, extraversion, and openness, respectively. The remaining five-psychoticism, masculinity versus femininity, religious orthodoxy, somatic complaints, and inadequacy-corresponded to the five-factor model's facets and styles (combinations of two domains) or were unrelated to the five-factor model. In age-adjusted and fully adjusted models, cynicism was associated with greater all-cause and cancer mortality. In fully adjusted models, inadequacy was associated with lower all-cause mortality and lower mortality from other causes. In age-adjusted models, religious orthodoxy was associated with lower cancer mortality. Further analyses revealed that the association between cynicism and all-cause mortality waned over time. Exploratory analyses of death from any disease of the circulatory system revealed no further associations. These findings reveal the importance of cynicism (disagreeableness) as a mortality risk factor, show that associations between cynicism and all-cause mortality are limited to certain periods of the lifespan, and highlight the need to study personality styles or types, such as inadequacy, that involve high neuroticism, low extraversion, and low conscientiousness. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Salt intake and prevalence of overweight/obesity in Japan, China, the United Kingdom, and the United States: the INTERMAP Study.

BACKGROUND: Several studies have reported that dietary salt intake may be an independent risk factor for overweight/obesity, but results from previous studies are controversial, reflecting study limitations such as use of a single spot urine or dietary recall to estimate daily salt intake rather than 24-h urine collections, and population samples from only a single country or center. OBJECTIVE: The aim of this study was to use data from the International Study of Macro-/Micro-nutrients and Blood Pressure (INTERMAP Study) to explore the relation between dietary salt intake estimated from 2 timed 24-h urine collections and body mass index (BMI; in kg/m2) as well as prevalence of overweight/obesity in Japan, China, the United Kingdom, and the United States. METHODS: Data were from a cross-sectional study of 4680 men and women aged 40-59 y in Japan (n = 1145), China (n = 839), the United Kingdom (n = 501), and the United States (n = 2195). General linear models were used to obtain the regression coefficients (ß) of salt intake associated with BMI. Multivariable logistic regression models were used to determine the ORs and 95% CIs of overweight/obesity associated with a 1-g/d higher dietary salt intake. RESULTS: After adjustment for potential confounding factors including energy intake, salt intake 1 g/d higher was associated with BMI higher by 0.28 in Japan, 0.10 in China, 0.42 in the United Kingdom, and 0.52 in the United States, all P values < 0.001. Salt intake 1 g/d higher was associated with odds of overweight/obesity 21% higher in Japan, 4% higher in China, 29% higher in the United Kingdom, and 24% higher in the United States, all P values < 0.05. CONCLUSIONS: Salt intake is positively associated with BMI and the prevalence of overweight/obesity in Japan, China, the United Kingdom, and the United States. This association needs to be further confirmed in well-designed prospective studies with repeated dietary and BMI measurements.This trial was registered at clinicaltrials.gov as NCT00005271.

Urinary sodium-to-potassium ratio and intake of sodium and potassium among men and women from multiethnic general populations: the INTERSALT Study.

The Na/K ratio may be more strongly related to blood pressure and cardiovascular disease than sodium or potassium. The casual urine Na/K ratio can provide prompt on-site feedback, and with repeated measurements, may provide useful individual estimates of the 24-h ratio. The World Health Organization has published guidelines for sodium and potassium intake, but no generally accepted guideline prevails for the Na/K ratio. We used standardized data on 24 h and casual urinary electrolyte excretion obtained from the INTERSALT Study for 10,065 individuals aged 20-59 years from 32 countries (52 populations). Associations between the casual urinary Na/K ratio and the 24-h sodium and potassium excretion of individuals were assessed by correlation and stratification analyses. The mean 24-h sodium and potassium excretions were 156.0 mmol/24 h and 55.2 mmol/24 h, respectively; the mean 24-h urinary Na/K molar ratio was 3.24. Pearson's correlation coefficients (r) for the casual urinary Na/K ratio with 24-h sodium and potassium excretions were 0.42 and -0.34, respectively, and these were 0.57 and -0.48 for the 24-h ratio. The urinary Na/K ratio predicted a 24-h urine Na excretion of <85 mmol/day (the WHO recommended guidelines) with a sensitivity of 99.7% and 94.0%, specificity of 39.5% and 48.0%, and positive predictive value of 96.3% and 61.1% at the cutoff point of 1 in 24 h and casual urine Na/K ratios, respectively. A urinary Na/K molar ratio <1 may be a useful indicator for adherence to the WHO recommended levels of sodium and, to a lesser extent, the potassium intake across different populations; however, cutoff points for Na/K ratio may be tuned for localization.

Agreement between 24-h dietary recalls and 24-h urine collections for estimating sodium intake in China, Japan, UK, USA: the International Study of Macro- and Micro-nutrients and Blood Pressure.

OBJECTIVE: The present study aims to compare 24-h dietary recalls with 24-h urine collections for the estimation of sodium intake at both population and individual levels in China, Japan, the United Kingdom (UK), and the United States of America (USA), using data from the International Study of Macro- and Micro-nutrients and Blood Pressure (INTERMAP). METHODS: Mean differences between 24-h dietary recalls and 24-h urine collections were calculated for their agreement in estimating sodium intake at the population level; relative and absolute differences as well as misclassification of salt intake groups (salt intake <6, 6-8.9, 9-11.9, 12-14.9, and ≥15 g/day) were used to determine the agreement at the individual level. RESULTS: The mean differences (95% CI) between dietary recalls and urine collections for China, Japan, UK, and USA were -54.0 (-59.8, -48.3), 3.9 (0.6, 7.2), 2.9 (-1.8, 7.6), and -3.5 (-5.8, -1.1) mmol/day, respectively. The proportions of individual relative differences beyond ±40% were 34.3% for China, 16.9% for Japan, 24.2% for UK, and 21.3% for USA; the proportions of individual absolute differences greater than 51.3 mmol/day (3 g salt) were 58.6% for China, 32.8% for Japan, 25.4% for UK, and 31.9% for USA. The rate for misclassification of salt intake groups at individual level for China, Japan, UK, and USA were 71.4, 60.9, 58.7, and 60.0%, respectively. CONCLUSION: The 24-h dietary recalls demonstrate greater agreement with the 24-h urine collections in estimating population sodium intake for Japan, UK, and USA, compared with China. The 24-h dietary recall has poor performance in assessing individual sodium intake in these four countries.

The Relationship of Dietary Cholesterol with Serum Low-Density Lipoprotein Cholesterol and Confounding by Reverse Causality: The INTERLIPID Study.

AIM: The positive relationship between dietary cholesterol and serum cholesterol has been questioned by a set of recent cohort studies. This study aimed to investigate how employment status and education years relate to the association between dietary cholesterol and serum low-density lipoprotein cholesterol (LDL-C) in a Japanese population. METHODS: A population-based, random sample, cross-sectional study (INTERLIPID) was performed. Among 1,145 Japanese individuals aged 40-59 years, 106 were excluded because of special diets, use of lipid-lowering drugs, hormone replacement, and missing data, leaving 1,039 individuals (533 men and 506 women). Dietary cholesterol was assessed from four 24-h dietary recalls, and LDL-C was measured enzymatically with an auto-analyzer. A standard questionnaire inquired about employment status and education years. RESULTS: In men, a 1 standard deviation (SD) higher dietary cholesterol was associated with 3.16 mg/dL lower serum LDL-C (P=0.009; unadjusted model). After adjustment for covariates, higher serum LDL-C was estimated per 1 SD higher intake of dietary cholesterol in nonemployed men [self-employed, homemakers, farmers, fishermen, and retired employees; ß=＋9.08, 95% confidence interval (CI)=＋0.90-＋17.27] and less educated men (ß=＋4.46, 95% CI=－0.97-＋9.90), whereas an inverse association was observed in employed men (ß=－3.02, 95% CI=－5.49-－0.54) and more educated men (ß=－3.66, 95% CI=－6.25-－1.07). CONCLUSIONS: In men who were nonemployed and less educated, a higher intake of dietary cholesterol was associated with elevated concentrations of serum LDL-C, whereas an inverse association was observed in men who were employed and more educated.

Factors associated with intra-individual visit-to-visit variability of blood pressure in four countries: the INTERMAP study.

Several studies demonstrated that visit-to-visit variability of blood pressure (BP) predicted future events of total death, stroke and cardiovascular disease. Little is known about factors associated with visit-to-visit BP variability in different countries. We recruited participants aged 40-59 years from four countries (Japan, the People's Republic of China [PRC], the United Kingdom [UK] and the United States [US]). At each study visit, BP was measured twice by trained observers using random zero sphygmomanometers after five minutes resting. We defined visit-to-visit BP variability as variation independent of mean (VIM) by using average systolic BP of 1st and 2nd measurement across four study visits. Data on 4680 men and women were analyzed. Mean ± standard deviation of VIM values among participants in Japan, the PRC, the UK and the US were 5.44 ± 2.88, 6.85 ± 3.49, 5.65 ± 2.81 and 5.84 ± 3.01, respectively; VIM value in the PRC participants was significantly higher. Sensitivity analyses among participants without antihypertensive treatment or past history of cardiovascular disease yielded similar results. Higher VIM value was associated with older age, female gender, lower pulse rate and urinary sodium excretion and use of antihypertensive agents such as angiotensin converting enzyme inhibitors, beta blockers and calcium channel blockers. The difference of visit-to-visit BP variability between PRC and other countries remained significant after adjustment for possible confounding factors. In this large international study across four countries, visit-to-visit BP variability in the PRC was higher than in the other three countries. Reproducibility and mechanisms of these findings remain to be elucidated.