Elevated plasma and urinary concentrations of green tea catechins associated with improved plasma lipid profile in healthy Japanese women.

This study investigated green tea catechins in plasma and urine and chronic disease biomarkers. We hypothesized that plasma and urinary concentration of green tea catechins are associated with cardiovascular disease and diabetes biomarkers. First void urine and fasting plasma samples were collected from 57 generally healthy females aged 38 to 73 years (mean, 52 ± 8 years) recruited in Himeji, Japan. The concentrations of plasma and urinary green tea catechins were determined by liquid chromatography coupled with mass tandem spectrometer. Low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, triglyceride, glucose, insulin, glycated hemoglobin, and C-reactive protein in plasma/serum samples were analyzed by a commercial diagnostic laboratory. Statistical associations were assessed using Spearman correlation coefficients. The results showed weak associations between plasma total catechin and triglyceride (r = -0.30) and LDL cholesterol (r = -0.28), whereas plasma (-)-epigallocatechin-3-gallate, (-)-epigallocatechin, (-)-epicatechin-3-gallate, and (-)-epicatechin exhibited weak to moderate associations with triglyceride or LDL cholesterol, but little associations with HDL cholesterol, body fat, and body mass index were evident. Urinary total catechin was weakly associated with triglyceride (r = -0.19) and LDL cholesterol (r = -0.15), whereas urinary (-)-epigallocatechin-3-gallate (r = -0.33), (-)-epigallocatechin (r = -0.23), and (-)-epicatechin-3-gallate (r = -0.33) had weak to moderate correlations with triglyceride and similarly with body fat and body mass index. Both plasma (r = -0.24) and urinary (r = -0.24) total catechin, as well as individual catechins, were weakly associated with glycated hemoglobin. Plasma total and individual catechins were weakly to moderately associated with C-reactive protein, but not the case for urinary catechins. In conclusion, we found weak to moderate associations between plasma and urinary green tea catechin concentrations and plasma biomarkers of cardiovascular disease and diabetes.

Urinary phytoestrogens and cancer, cardiovascular, and all-cause mortality in the continuous National Health and Nutrition Examination Survey.

PURPOSE: Experimental studies suggest that phytoestrogen intake alters cancer and cardiovascular risk. This study investigated the associations of urinary phytoestrogens with total cancer (n = 79), cardiovascular (n = 108), and all-cause (n = 290) mortality among 5179 participants in the continuous National Health and Nutrition Examination Survey (1999-2004). METHODS: Urinary phytoestrogens were measured using high-performance liquid chromatography with tandem mass spectrometric detection. Survival analysis was performed to evaluate hazard ratios (HRs) and 95 % confidence intervals (CIs) for each of the three outcomes in relation to urinary phytoestrogens. RESULTS: After adjustment for confounders, higher urinary concentrations of total enterolignans were associated with a reduced risk of death from cardiovascular disease (HR for tertile 3 vs. tertile 1 0.48; 95 % CI 0.24, 0.97), whereas higher urinary concentrations of total isoflavones (HR for tertile 3 vs. tertile 1 2.14; 95 % CI 1.03, 4.47) and daidzein (HR for tertile 3 vs. tertile 1 2.05; 95 % CI 1.02, 4.11) were associated with an increased risk. A reduction in all-cause mortality was observed for elevated urinary concentrations of total enterolignans (HR for tertile 3 vs. tertile 1 0.65; 95 % CI 0.43, 0.96) and enterolactone (HR for tertile 3 vs. tertile 1 0.65; 95 % CI 0.44, 0.97). CONCLUSIONS: Some urinary phytoestrogens were associated with cardiovascular and all-cause mortality in a representative sample of the US population. This is one of the first studies that used urinary phytoestrogens as biomarkers of their dietary intake to evaluate the effect of these bioactive compounds on the risk of death from cancer and cardiovascular disease.

Cardiometabolic risk factors are associated with high urinary enterolactone concentration, independent of urinary enterodiol concentration and dietary fiber intake in adults.

The study objective was to evaluate independent and interactive associations of dietary fiber intake and high urinary enterolignans with cardiometabolic risk factors. The analysis included 2260 adults (≥20 y of age) from the 2003-2010 NHANES. Logistic regression models were used to evaluate obesity and clinically defined cardiometabolic risk factors in relation to dietary fiber intake and urinary enterolignan concentrations. Three sets of models were created: 1) independent associations, 2) mutually adjusted associations, and 3) interactions. Models were adjusted for age, gender, race/ethnicity, education, smoking status, and energy intake. High concentrations were considered to be above the 90th percentile of urinary enterolignan concentrations. Increasing dietary fiber intake was associated with high blood pressure (P = 0.02) and low serum HDL cholesterol (P-trend = 0.03). High urinary enterodiol concentration was not associated with obesity or cardiometabolic risk factors. High urinary enterolactone concentration was inversely associated with obesity (OR: 0.44; 95% CI: 0.29, 0.66), abdominal obesity (OR: 0.58; 95% CI: 0.39, 0.87), high serum C-reactive protein (CRP; OR: 0.52; 95% CI: 0.37, 0.74), high serum triglycerides (OR: 0.39; 95% CI: 0.23, 0.61), low serum HDL cholesterol (OR: 0.37; 95% CI: 0.23, 0.61), and metabolic syndrome (OR: 0.47; 95% CI: 0.30, 0.74). In mutually adjusted models, enterolactone associations observed in independent models remained similar, but associations for dietary fiber intake were attenuated, with the exception of blood pressure. In interaction models, there were 2 significant interactions: between high urinary enterodiol concentration and dietary fiber intake for high serum CRP (P = 0.04) and high plasma glucose (P = 0.04). Overall, being in the highest 10% of urinary enterolactone concentration was associated with cardiometabolic risk factors, independent of dietary fiber intake and enterodiol concentration. Future studies are warranted to evaluate physiologic actions of enterolactone or aspects of the gut microbial profile responsible for lignan metabolism to enterolactone.

The association between urinary phytoestrogen excretion and components of the metabolic syndrome in NHANES.

BACKGROUND: Metabolic syndrome is a major risk factor for cardiovascular diseases, which are still the major cause of death in developed countries. METHODS: We cross-sectionally studied the association between urinary phytoestrogen excretion and metabolic cardiovascular risk factors. Hence, we used data from the National Health and Nutrition Examination Survey from 1999 to 2004 with 1,748 participants, who had urine levels of isoflavones and lignans measured. Geometric means of waist circumference, blood pressure, fasting glucose, HDL cholesterol, and triglyceride levels were computed by quartiles of isoflavone or lignan urinary excretion. Outcome was assessed as the presence of metabolic syndrome according to NCEP-ATP III criteria. The association between phytoestrogen concentration and the metabolic syndrome was calculated using logistic regression analyses. RESULTS: Plasma triglyceride and HDL cholesterol levels were lower in participants in the highest quartile of lignan excretion compared with the lowest (both P < 0.01). However, blood pressure, waist circumference, and plasma glucose levels did not differ significantly between extreme quartiles. The presence of metabolic syndrome was lower with increasing levels of urinary lignans (OR 0.48, 95% CI 0.28; 0.80 top vs. bottom quartile), especially when separately computed for the excretion of enterolactone (OR 0.47, 95% CI 0.28; 0.78). There was no significant association between isoflavone excretion and any component of the metabolic syndrome. CONCLUSIONS: Our study shows that an increasing excretion of lignans, especially enterolactone, might be associated with a decreased presence of the metabolic syndrome.

Urinary isoflavone concentrations are inversely associated with cardiometabolic risk markers in pregnant U.S. women.

Some evidence suggests that phytoestrogens, such as soy-derived isoflavones, may have beneficial effects on cardiovascular health and glycemic control. These data are mainly limited to postmenopausal women or individuals at elevated cardiometabolic risk. There is a lack of data for pregnant women who have elevated estrogen levels and physiologically altered glucose and lipid metabolism. We analyzed data from 299 pregnant women who participated in the NHANES 2001-2008 surveys. Multivariable linear regression analyses were used to examine the association between urinary concentrations of isoflavonoids and cardiometabolic risk markers, adjusted for body mass index, pregnancy trimester, total energy intake, dietary intake of protein, fiber, and cholesterol, and demographic and lifestyle factors. Cardiometabolic risk markers were log-transformed, and geometric means were calculated by quartiles of urinary concentrations of isoflavonoids. Comparing women in the highest vs. lowest quartiles of urine total isoflavone concentrations, we observed significant, inverse associations with circulating concentrations of fasting glucose (79 vs. 88 mg/dL, P-trend = 0.0009), insulin (8.2 vs. 12.8 µU/mL, P-trend = 0.03), and triglyceride (156 vs. 185 mg/dL, P-trend = 0.02), and the homeostasis model assessment of insulin resistance (1.6 vs. 2.8, P-trend = 0.01), but not for total, low-density lipoprotein cholesterol and high-density lipoprotein cholesterol. The concentrations of individual isoflavonoids, daidzein, equol, and O-desmethylangolensin were inversely associated with some cardiometabolic risk markers, although no clear pattern emerged. These data suggest that there may be a relation between isoflavone intake and cardiometabolic risk markers in pregnant women.

Fractional excretion of phosphorus modifies the association between fibroblast growth factor-23 and outcomes.

Fibroblast growth factor-23 (FGF23) induces phosphaturia through its effects on renal tubules. Higher levels of FGF23 associate with cardiovascular disease (CVD) events and all-cause mortality, but it is unknown whether these associations differ by the degree of phosphaturia. Here, we measured serum FGF23 and 24-hour urine fractional excretion of phosphorus (FePi) in 872 outpatients with stable CVD and a mean estimated GFR of 71 ml/min per 1.73 m(2). During an average 7.5 years of follow-up, there were 337 deaths and 199 CVD events. Urinary FePi significantly modified the association of FGF23 with each outcome (P interaction<0.001 for all-cause mortality and P interaction<0.05 for CVD events). In models adjusted for CVD risk factors, kidney function, and PTH, those patients who had FGF23 above the median (≥ 42.3 relative units [RU]/ml) but FePi below the median (<15.7%) had the highest risks of both all-cause mortality (HR=1.98, 95% CI=1.42-2.77) and CVD events (HR=1.92, 95% CI=1.25-2.94) compared with those patients who had low concentrations of FGF23 and low FePi. In summary, associations of FGF23 with mortality and CVD events are stronger in persons with lower FePi independent of PTH and kidney function. In such individuals, the renal tubular response to FGF23 may be suboptimal.

24-hour urine phosphorus excretion and mortality and cardiovascular events.

BACKGROUND AND OBJECTIVES: Higher morning serum phosphorus has been associated with cardiovascular disease (CVD) in patients with or without CKD. In patients with CKD and a phosphorous level >4.6 mg/dl, the Kidney Disease Improving Global Outcomes guidelines recommend dietary phosphorus restriction. However, whether phosphorus restriction influences serum phosphorus concentrations and whether dietary phosphorus is itself associated with CVD or death are uncertain. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Among 880 patients with stable CVD and normal kidney function to moderate CKD, 24-hour urine phosphorus excretion (UPE) and serum phosphorus were measured at baseline. Participants were followed for a median of 7.4 years for CVD events and all-cause mortality. RESULTS: Mean ± SD age was 67±11 years, estimated GFR (eGFR) was 71±22 ml/min per 1.73 m(2), and serum phosphorus was 3.7±0.6 mg/dl. Median UPE was 632 (interquartile range, 439, 853) mg/d. In models adjusted for demographic characteristics and eGFR, UPE was weakly and nonsignificantly associated with serum phosphorus (0.03 mg/dl higher phosphorus per 300 mg higher UPE; P=0.07). When adjusted for demographics, eGFR, and CVD risk factors, each 300-mg higher UPE was associated with 17% lower risk of CVD events. The association of UPE with all-cause mortality was not statistically significant (hazard ratio, 0.93; 95% confidence interval, 0.82 to 1.05). Results were similar irrespective of CKD status (P interactions > 0.87). CONCLUSIONS: Among outpatients with stable CVD, the magnitude of the association of UPE with morning serum phosphorus is modest. Greater UPE is associated with lower risk for CVD events. The association was similar for all-cause mortality but was not statistically significant.

A crossover comparison of urinary albumin excretion as a new surrogate marker for cardiovascular disease among 4 types of calcium channel blockers.

BACKGROUND: At the intervention for cardiovascular disease (CVD), albuminuria is a new pivotal target. Calcium channel blocker (CCB) is one of the most expected agents. Currently CCBs have been classified by delivery system, half-life and channel types. We tested anti-albuminuric effect among 4 types of CCBs. METHODS: Subjects were 50 hypertensives (SBP/DBP 164.7±17.1/92.3±12.2mmHg, s-Cr 0.81±0.37mg/dl, urinary albumin excretion (UAE) 69.4 (33.5-142.6) mg/gCr). Four CCBs were administered in a crossover setting: nifedipine CR, a long biological half-life L type by controlled release; cilnidipine, an N/L type; efonidipine, a T/L type; and amlodipine, a long biological half-life L type. RESULTS: Comparable BP reductions were obtained. UAE at endpoints ware as follows (mg/gCr, *P<0.01): nifedipine CR 30.8 (17.3-81.1),* cilnidipine 33.9 (18.0-67.7),* efonidipine 51.0 (21.2-129.8), amlodipine 40.6 (18.7-94.7). By all agents, significant augmentations were observed in PRA, angiotensin I and angiotensin II (AngII). AngII at cilnidipine was significantly lower than that at amlodipine. PAC at cilnidipine and efonidipine was significantly lower than that at amlodipine. Nifedipine CR significantly reduced ANP concentration. CONCLUSIONS: It is revealed that only nifedipine CR and cilnidipine could reduce albuminuria statistically. Thus, it is suggested that the 2 CCBs might be favorable for organ protection in hypertensives.

Dietary selenium (Se) and vitamin E (V(E)) supplementation modulated methylmercury-mediated changes in markers of cardiovascular diseases in rats.

Epidemiological studies demonstrated that human exposure to methylmercury (MeHg) may contribute to the development and progression of metabolic and cardiovascular disorders. However, the mechanisms involved and the role of selenium (Se) and vitamin E (V(E)) supplementation in modulating MeHg cardiovascular toxicities remain unclear. This study examined the effects of Se and V(E) supplementation on MeHg-mediated systemic oxidative stress, antioxidant defense, inflammation, and endothelial dysfunction in an animal model. Male Sprague-Dawley rats were fed a starch-based casein diet or the same diet supplemented with 1 or 3 mg Se/kg diet and with or without 250 or 750 mg V(E)/kg diet. After 28 days of dietary treatment, rats were gavaged with 0 or 3 mg MeHg/kg BW for 14 consecutive days. Results suggested that exposure to MeHg may increase the risk of cardiovascular disease by decreasing circulating paraoxonase-1 activities, increasing serum oxidized low density lipoprotein levels, and associated systemic inflammation and endothelial dysfunction as reflected by increased leukocyte counts and serum levels of intercellular adhesion molecule-1 and monocyte chemotactic protein-1. Se and V(E) supplementation may either alleviate or augment the effects of MeHg, depending on their doses and combinations.

Relation of sex and estrogen therapy to serum fibroblast growth factor 23, serum phosphorus, and urine phosphorus: the Heart and Soul Study.

BACKGROUND: Menopause is associated with urine phosphorus retention, which is mitigated by estrogen therapy. Fibroblast growth factor 23 (FGF-23) is a hormone originating from bone that regulates urine phosphorus excretion. Whether sex or estrogen therapy is associated with different FGF-23 levels is unknown. STUDY DESIGN & SETTING: Cross-sectional study of ambulatory individuals with prevalent cardiovascular disease. PREDICTORS: Sex and, in women, use or nonuse of estrogen. OUTCOMES: Serum phosphorus, tubular maximum reabsorption of phosphorus indexed to glomerular filtration rate (TMP/GFR), and plasma FGF-23 concentrations. RESULTS: For 987 participants, mean age was 67 ± 11 years, 182 (18%) were women, and 46 (25%) were using estrogen. Mean estimated GFR was 71 ± 23 (SD) mL/min/1.73 m(2). Compared with women who were not using estrogen, both women on estrogen therapy and men had significantly lower serum phosphorus concentrations, lower TMP/GFR values (indicating higher urine phosphorus excretion), and lower FGF-23 concentrations with adjustment for age, demographics, and kidney function (P < 0.001 for each). Mean FGF-23 levels were 68.7 (95% CI, 59.7-79.0) relative units (RU)/mL in non-estrogen-using women, 43.8 (95% CI, 41.2-46.5) RU/mL in men, and 45.1 (95% CI, 35.2-57.4) RU/mL in women using estrogen in adjusted analysis (P < 0.001). LIMITATIONS: Most participants were men. Estrogen therapy was not randomly assigned. CONCLUSIONS: Older women who are not using estrogen have higher FGF-23 levels than either men or women using estrogen. In the context of prior literature, these data suggest that postmenopausal phosphorus retention may stimulate higher FGF-23 concentrations after menopause.

Effect of a traditional Chinese medicine preparation Xindi soft capsule on rat model of acute blood stasis: a urinary metabonomics study based on liquid chromatography-mass spectrometry.

Xindi soft capsule is a traditional Chinese medicine preparation which consists of sea buckthorn flavonoids and sea buckthorn berry oil. In this study, a urinary metabonomics method based on the ultra-performance liquid chromatography combined with quadrupole time-of-flight tandem mass spectrometry (UPLC Q-TOF MS) was used to evaluate the efficacy and study the mechanism of traditional Chinese medicine preparation to blood stasis. With pattern recognition analysis (principal component analysis and partial least squares-discriminate analysis) of urinary metabolites, a clear separation of acute blood stasis model group and healthy control group was achieved, the dose groups were located between acute blood stasis model group and healthy control group showing a tendency of recovering to healthy control group, high dose and middle dose were more effective than low dose. Some significantly changed metabolites like cholic acid, phenylalanine and kynurenic acid have been found and identified and used to explain the mechanism. The work shows that the metabonomics method is a valuable tool in the research mechanism of traditional Chinese medicine.

Serum selenium predicts levels of F2-isoprostanes and prostaglandin F2alpha in a 27 year follow-up study of Swedish men.

Low concentrations of selenium (Se) predict mortality and cardiovascular diseases in some populations. The effect of Se on in vivo indicators of oxidative stress and inflammation, two important features of atherosclerosis, in human populations is largely unexplored. This study investigated the longitudinal association between serum selenium (s-Se) and a golden standard indicator of oxidative stress in vivo (8-iso-prostaglandin F2alpha, a major F2-isoprostane), an indicator of cyclooxygenase (COX)-mediated inflammation (prostaglandin F2alpha), high sensitive C-reactive protein (hsCRP), interleukin-6 (IL-6) and serum amyloid A protein (SAA) in a follow-up study of 27 years. The s-Se was measured in 615 Swedish men at 50 years of age in a health investigation. The status of oxidative stress and inflammation was evaluated in a re-investigation 27 years later by quantification of urinary 8-iso-PGF2alpha and 15-keto-dihydro-PGF2alpha (a major metabolite of PGF2alpha) and serum hsCRP, SAA and IL-6. Men in the highest quartile of s-Se at age 50 had decreased levels of 8-iso-PGF2alpha compared to all lower quartiles and decreased levels of PGF2alpha compared to all lower quartiles at follow-up. These associations were independent of BMI, diabetes, hyperlipidemia, hypertension, smoking, alpha-tocopherol and beta-carotene at baseline. The s-Se was not associated with hsCRP, SAA or IL-6 at follow-up. In conclusion, high concentrations of s-Se predict reduced levels of oxidative stress and subclinical COX-mediated (but not cytokine-mediated) inflammation in a male population. The associations between Se, oxidative stress and inflammation, respectively, might be related to the proposed cardiovascular protective property of Se.

Worldwide epidemic of obesity: hope for Japanese diets.

1. WHO-coordinated Cardiovascular Diseases and Alimentary Comparison Study (CARDIAC) and its follow-up, MONALISA Study covering 60 populations in 25 countries indicated an increasing prevalence of obesity, even in developing countries. 2. The index of obesity, BMI was confirmed to be related positively with both systolic and diastolic blood pressure (BP) in 60 CARDIAC populations and with the age-adjusted mortality rates of coronary heart diseases (CHD) in 25 populations where reliable demographic data were available. 3. CHD mortality rates were inversely related with biomarkers for soy bean and fish intakes, isoflavones and taurine in 24-h urine samples in 25 CARDIAC study populations. 4. Population samples were divided into two groups: soy eaters and non-eaters as well as fish eaters and non-eaters, respectively, based on WHO-CARDIAC study data. Soy eaters as well as fish eaters had significantly lower BMI, BP and serum cholesterol levels, which are three major CHD risk factors. 5. BMI was inversely related with 24-h urinary isoflavones excretion, the biomarker of soy intake and also with 24-h urinary excretion of histidine, relatively rich in fish. 6. Since both nutrients, isoflavones as phytoestrogen and histidine as the precursor of histamine may affect central appetite mechanisms, soy and fish intake may be recommended to control obesity, the major common risk of lifestyle-related diseases.

Cardiovascular risk, renal hypertensive damage, and effects of amlodipine treatment in transgenic TGR(mREN2)27 rats.

Transgenic rats (TGRs) TGR(mREN2)27 are characterized by fulminant hypertension, an inverse circadian blood pressure rhythm, and severe hypertensive target organ damage. In the present study, we evaluated cardiovascular risk factors, renal function, and urinary protein loss in transgenic rats before and after treatment with the calcium channel blocker amlodipine. Amlodipine was injected intraperitoneally in a dose of 5 mg/kg/day, either once daily at 8.00 h or twice daily in divided doses at 8.00 and 20.00 h. Untreated TGRs and Sprague-Dawley rats served as hypertensive and normotensive controls, respectively. Before and after 5 weeks of treatment, rats were placed in metabolic cages for sampling of urine. Prior to treatment, urinary excretion rates of protein, albumin, and Ca2+ were significantly higher in TGRs than in Sprague-Dawley controls. Urinary excretion of protein and albumin was reduced by 5 weeks of amlodipine treatment, whereas the excretion of Ca2+ was not affected. The reductions in renal proteinuria and albuminuria by amlodipine treatment were significantly correlated with the treatment-induced decrease in blood pressure. These findings indicate that blood pressure itself is an important contributor to albumin loss by the kidney in renin-dependent hypertension of TGRs.

Serum and urine selenium concentrations in patients with cardiovascular diseases and relationship to other nutritional indexes.

Serum and urine selenium levels were determined in patients with cardiovascular diseases by hydride generation atomic absorption spectrometry. Mean serum Se concentrations measured in patients with acute myocardial infarction (AMI; n = 32) or with ischemic cardiomyopathy (n = 50) were significantly lower than those determined in control groups. In AMI patients, serum triglyceride levels showed a positive significant correlation with the serum Se concentration (r = 0.59, p < 0.05). This result reinforces the important role of Se as an antioxidant agent in this disease. Mean urine Se concentrations of AMI patients (n = 33) were also significantly lower to those determined in the control group (p < 0. 05). This reaction of the organism contributes to regulate the Se homeostasis to keep the body Se status as high as possible.

[Iodine deficiency in cardiovascular diseases]. / Jódhiány elöfordulása cardiovascularis megbetegedésekben.

The thyroid hormone deficiency on cardiovascular function can be characterized with decreased myocardial contractility and increased peripheral vascular resistance as well as with the changes in lipid metabolism. 42 patients with cardiovascular disease (mean age 65 +/- 13 yr, 16 males) were investigated if iodine insufficiency can play a role as a risk factor for the cardiovascular diseases. The patients were divided in 5 subgroups on the ground of the presence of hypertension, congestive heart failure, cardiomyopathy, coronary disfunction and arrhythmia. Urine iodine concentration (5.29 +/- 4.52 micrograms/dl) was detected with Sandell-Kolthoff colorimetric reaction. The most decreased urine iodine concentration was detected in the subgroups with arrhythmia and congestive heart failure (4.7 +/- 4.94 micrograms/dl and 4.9 +/- 4.81 micrograms/dl, respectively). An elevated TSH level was found by 3 patients (5.3 +/- 1.4 mlU/l). An elevation in lipid metabolism (cholesterol, triglyceride) associated with all subgroups without arrhythmia. In conclusion, the occurrence of iodine deficiency in cardiovascular disease is frequent. Iodine supplementation might prevent the worsing effect of iodine deficiency on cardiovascular disease.

The effect of boron supplementation on its urinary excretion and selected cardiovascular risk factors in healthy male subjects.

Boron (B) is an essential trace element for plants and its interrelationship with mineral and bone metabolism and endocrine function in humans has been proposed. Relatively little is known about the occurrence of B in the food chain and hence a biomarker which reflects its intake is required. Two studies were carried out to quantify the urinary B concentration of subjects consuming their habitual diet and the effect of supplementation. In addition, the effect of supplementation on plasma lipoprotein cholesterol concentrations and susceptibility to oxidation and plasma steroid hormones were determined. Boron excretion, obtained on two different occasions from 18 healthy male subjects, was found to be in the range 0.35-3.53 mg/day, with no significant difference between the two occasions. Supplementation with 10 mg B/d for 4 wk resulted in 84% of the supplemented dose being recovered in the urine. Plasma estradiol concentrations increased significantly as a result of supplementation (51.9 +/- 21.4 to 73.9 +/- 22.2 pmol/L; p < 0.004) and there was a trend for plasma testosterone levels to be increased. However, there was no difference in plasma lipids or the oxidizability of low-density lipoprotein. Our studies suggest that the absorption efficiency of B is very high and estimation of the urinary B concentration may provide a useful reflection of B intake. In addition, the elevation of endogenous estrogen as a result of supplementation suggests a protective role for B in atherosclerosis.