Relation of nutrient intake to microalbuminuria in nondiabetic middle-aged men and women: International Population Study on Macronutrients and Blood Pressure (INTERMAP)

Evaluation of plasma vitamin E and development of proteinuria in hypertensive patients

Background

The prospective relationship between plasma vitamin E levels and proteinuria remains uncertain. We aimed to evaluate the association between baseline plasma vitamin E levels and the development of proteinuria and examine any possible effect modifiers in patients with hypertension.

Methods

This was a post hoc analysis of the renal sub-study of the China Stroke Primary Prevention Trial (CSPPT). In total, 780 participants with vitamin E measurements and without proteinuria at baseline were included in the current study. The study outcome was the development of proteinuria, defined as a urine dipstick reading of a trace or ≥ 1+ at the exit visit.

Results

During a median follow-up duration of 4.4 years, the development of proteinuria occurred in 93 (11.9%) participants. Overall, there was an inverse relationship between plasma vitamin E and the development of proteinuria (per standard deviation [SD] increment; odds ratio [OR]: 0.73, 95% confidence interval [CI]: 0.55-0.96). Consistently, when plasma vitamin E was assessed as quartiles, lower risk of proteinuria development was found in participants in quartiles 2-4 (≥ 7.3 μg/mL; OR: 0.57, 95% CI: 0.34-0.96) compared to those in quartile 1. None of the variables, including sex, age, and body mass index, significantly modified the association between vitamin E and proteinuria development.

Conclusion

There was a significant inverse association between plasma vitamin E levels and the development of proteinuria in patients with hypertension. The results were consistent among participants with different baseline characteristics.

Alcohol consumption and microvascular dysfunction: a J-shaped association: The Maastricht Study

BACKGROUND

Microvascular dysfunction (MVD) is an important contributor to major clinical disease such as stroke, dementia, depression, retinopathy, and chronic kidney disease. Alcohol consumption may be a determinant of MVD.

OBJECTIVE

Main objectives were (1) to study whether alcohol consumption was associated with MVD as assessed in the brain, retina, skin, kidney and in the blood; and (2) to investigate whether associations differed by history of cardiovascular disease or sex.

DESIGN

We used cross-sectional data from The Maastricht Study (N = 3,120 participants, 50.9% men, mean age 60 years, and 27.5% with type 2 diabetes [the latter oversampled by design]). We used regression analyses to study the association between total alcohol (per unit and in the categories, i.e. none, light, moderate, high) and MVD, where all measures of MVD were combined into a total MVD composite score (expressed in SD). We adjusted all associations for potential confounders; and tested for interaction by sex, and history of cardiovascular disease. Additionally we tested for interaction with glucose metabolism status.

RESULTS

The association between total alcohol consumption and MVD was non-linear, i.e. J-shaped. Moderate versus light total alcohol consumption was significantly associated with less MVD, after full adjustment (beta [95% confidence interval], -0.10 [-0.19; -0.01]). The shape of the curve differed with sex (P_interaction = 0.03), history of cardiovascular disease (P_interaction < 0.001), and glucose metabolism status (P_interaction = 0.02).

CONCLUSIONS

The present cross-sectional, population-based study found evidence that alcohol consumption may have an effect on MVD. Hence, although increasing alcohol consumption cannot be recommended as a policy, this study suggests that prevention of MVD may be possible through dietary interventions.

A Scoping Review of Epidemiological Studies on Intake of Sugars in Geographically Dispersed Asian Countries: Comparison of Dietary Assessment Methodology

Previous systematic reviews, which focused on sugar intake and its relation with health issues, were mainly conducted in Western countries, not Asian countries characterized by differences in dietary habits and disease prevalence. The scarcity of Asian studies may be attributed to the lack of assessment tools for estimating sugar intake. To provide an overview of the epidemiological studies on sugar intake in Asian countries, with a primary focus on dietary assessment methodology for estimating sugar intake, we conducted a scoping review of the epidemiological studies estimating sugar intake in Asian countries (the United Nations' definition) and Taiwan using PubMed and Web of Science. Study quality was evaluated based on its assessment of sugar intake in the whole diet, dietary assessment methods, and data sources used for estimating sugar content. We identified 143 studies from 136 publications from Eastern (n = 63), Southern (n = 30), South-Eastern (n = 26), and Western (n = 24) Asia. Total sugars were investigated in 95 studies, while 23-30 studies investigated sucrose, fructose, added sugars, and free sugars. The main aim of the selected studies was assessment of diet-disease relations (n = 85) and estimation of dietary intake (n = 40), and 62 studies assessed sugars as the primary exposure/outcome. A total of 120 studies assessed sugar intake in the whole diet, and 62 studies used validated FFQs or multiple-day dietary assessment methods. Only 41 studies used country-specific comprehensive food-composition databases or directly measured sugar content. Only 17 studies reported high-quality data. This review elucidated a sufficient number of epidemiological studies estimating sugar intake across Asian countries; however, most studies reported low-quality data. The results from our review showed that both feasible and validated dietary assessment methods, as well as comprehensive country-specific sugar-composition databases, are essential for producing high-quality studies with accurate sugar intake to examine its association with health outcomes.

Association between urinary salt excretion and albuminuria in Japanese patients with chronic kidney disease: the Fukuoka kidney disease registry study

BACKGROUND

Several large population-based studies have demonstrated that urinary salt excretion (USALT) is associated with albuminuria. However, this relationship has not been assessed in a large cohort study of patients with chronic kidney disease (CKD). Thus, the present study aimed to elucidate whether USALT was independently associated with albuminuria in a large cohort of patients with CKD.

METHODS

This cross-sectional study was conducted in 4075 patients with CKD not on dialysis. USALT (g/day) was estimated from spot urine. Patients were divided into quartiles (Q1-Q4) according to estimated USALT. Multivariable regression models were used to determine whether USALT was independently related to urinary albumin-to-creatinine ratio (UACR) or the presence of macroalbuminuria.

RESULTS

In multivariable linear regression analyses, 1-g/day increment in USALT was significantly associated with log UACR [coefficient 0.098, 95% confidence interval (CI) 0.075-0.121]. In addition, compared with the first USALT quartile, the third and fourth quartiles exhibited significant associations with log UACR (Q3: coefficient 0.305, 95% CI 0.154-0.456; Q4: coefficient 0.601, 95% CI 0.447-0.756). Furthermore, multivariable logistic regression analyses showed that USALT (1-g/day increment) was significantly associated with the presence of macroalbuminuria [odds ratio (OR) 1.11, 95% CI 1.07-1.14]; the third and fourth USALT quartiles exhibited significantly greater risks of macroalbuminuria, compared with the first quartile (Q3: OR 1.33, 95% CI 1.09-1.62; Q4: OR 1.89, 95% CI 1.54-2.32).

CONCLUSIONS

This significant association of USALT with UACR and macroalbuminuria suggests that higher USALT may cause increased albuminuria, thereby contributing to kidney disease progression.

Prevalence and risk factors of microalbuminuria in patients with lacunar infarction

Objectives: To investigate the prevalence and risk factors for microalbuminuria in patients with lacunar infarction. Methods: 702 lacunar infarction patients and 234 controls were recruited in this study, the concentration of urinary albumin and clinical characteristics were collected for each participant. We analyzed the prevalence of microalbuminuria in lacunar infarction patients, as well as the risk factors of microalbuminuria in patients with lacunar infarction. Results: The prevalence of microalbuminuria in patients with lacunar infarction was 32.8%, which was significantly higher than that in controls (9.8%, P＜0.001). Multiple linear regression analysis indicated that age, alcohol abuse, fasting blood glucose, systolic blood pressure, and triglyceride were positively associated with albumin/creatinine ratio levels. Multiple logistic regression analysis indicated that age (odds ratio [OR] = 1.067, 95% confidence interval [CI] = 1.029 to 1.105), alcohol abuse (OR = 3.001, 95% CI = 1.668 to 5.398), fasting blood glucose (OR = 2.014, 95% CI = 1.794 to 2.260), and systolic blood pressure (OR = 1.033, 95% CI = 1.010 to 1.056) were the independent risk factors for microalbuminuria in acute lacunar infarction patients, with high sensitivity, specificity, positive predictive value, and negative predictive value. Receiver operating characteristic curve analysis showed that the area under the curve for age, systolic blood pressure, and fasting blood glucose were 0.618 (cutoff value, 63.5 years; sensitivity, 54.8%; and specificity, 62.9%), 0.736 (cutoff level, 149.5 mmHg; sensitivity, 78.3%; and specificity, 61.2%) and 0.893 (cutoff value, 7 mmol/L; sensitivity, 92.2%; and specificity, 86%), respectively. Conclusion: Lacunar infarction was associated with higher microalbuminuria prevalence. Age, alcohol abuse, fasting blood glucose, and systolic blood pressure were individually significant and correlated factors of microalbuminuria in patients with lacunar infarction. More attention should be provided to this group of patients.

Renal function in relation to sodium intake: a quantitative review of the literature

We undertook a quantitative literature review to search for evidence underpinning current guidelines proposing a reduction of sodium intake to less than 2.4 g/d for the management of chronic kidney disease. We searched PubMed for peer-reviewed articles published from January 1980 through May 2016. Two investigators screened 5072 publications and extracted data from 36, including 11 cross-sectional and 5 longitudinal observational studies and 20 intervention trials. Within-study effect sizes were pooled and standardized to a sodium gradient of 100 mmol/d by using inverse-variance weighted random effects models. Among cross-sectional studies, the pooled odds ratio for albuminuria was 1.23 (95% confidence interval [CI], 0.92-1.64, P = 0.16), and the pooled mean difference in glomerular filtration rate amounted to 8.5 ml/min (CI, -2.3 to 19.2 ml/min; P = 0.12). In the cohort studies, the pooled relative risk of a renal endpoint was 1.08 (CI, 0.92-1.29; P = 0.35). In the intervention trials (median duration, 14 days [range, 4-186 days]), the mean differences in estimated glomerular filtration rate and albuminuria (high vs. low sodium intake) averaged 4.6 ml/min (CI, 3.4-5.8 ml/min; P < 0.0001) and 53% (CI, 21-84; P = 0.001), respectively. Cochran's Q statistic indicated significant heterogeneity among cross-sectional studies for both estimated glomerular filtration rate and albuminuria (P < 0.0001) and among intervention trials for albuminuria (P = 0.04). In conclusion, there is no robust evidence suggesting that long-term reduction of salt intake would prevent chronic kidney disease or delay its progression. However, our current findings, which were mainly obtained in people with slight renal impairment, cannot be extrapolated to patients with moderate or severe chronic kidney disease.

The relationship between sodium excretion and blood pressure, urine albumin, central retinal arteriolar equivalent

BACKGROUND

Many studies showed an association between dietary salt intake, blood pressure and increased CVD risk. The potential reason may be related to vascular structural and functional changes, through alterations in endothelial function. The central retinal arteriolar equivalent and urinary albumin reflected vascular endothelial dysfunction in different part of the body. The urinary sodium-creatinine ratio of causal urine specimens could represent the 24-h urinary sodium intake to estimate sodium intake.

METHODS

The 24-h sodium excretion was estimated by urinary sodium-creatinine ratio. Urinary albumin-creatinine ratio (UACR), reflecting renal arterial damage, was also determined. The central retinal arteriolar equivalent (CRAE) was detected by fundus photography and was further analyzed by semi-quantitative software.

RESULTS

Participants included 951 hypertensive patients with the average sodium excretion of 11.62 ± 3.01 g. The sodium excretion was significantly higher (P < 0.01) in the hypertensive as compared to that of the non-hypertensive participants. Prevalence of hypertension was increased with increasing sodium excretion. The sodium excretion was positively correlated with systolic blood pressure (SBP) and diastolic blood pressure (DBP), respectively (r = 0.20 and 0.14; P < 0.01). Furthermore, UACR and CRAE were significantly (P < 0.01) different within the sodium excretion quartiles (Q1-Q4). After adjusting the confounding variables, such as age and sex, the binary logistic regression analysis showed that sodium excretion was an independent factor of UACR and CRAE (P < 0.01).

CONCLUSION

Our results suggest that sodium excretion in the hypertensive participants were higher. The high sodium excretion was related with the renal arterial damage as well as retinal arteriolar changes.

Higher dietary salt intake is associated with microalbuminuria, but not with retinopathy in individuals with type 1 diabetes: the EURODIAB Prospective Complications Study

AIMS/HYPOTHESIS

High dietary salt intake has been associated with elevated BP and may also have a deleterious effect on microvascular complications. We studied the cross-sectional associations between dietary salt intake (estimated from 24 h urinary sodium excretion) and urinary potassium excretion on the one hand, and the prevalence of microvascular complications on the other, in individuals with type 1 diabetes.

METHODS

We measured sodium and potassium concentrations in two 24 h urine samples in 1,212 individuals with type 1 diabetes (40 ± 10 years old, 51% men) who participated in the EURODIAB Prospective Complications Study. We used multiple logistic regression analyses to investigate associations between dietary salt intake and microvascular complications adjusted for age and sex, and additionally for BMI, smoking, urinary potassium excretion, antihypertensive medication and physical activity, and total energy, protein, alcohol, saturated fat and fibre intake.

RESULTS

After full adjustment, 1 g/day higher dietary salt intake was positively associated with the presence of microalbuminuria (OR 1.06 [95% CI 1.01, 1.10]), but not macroalbuminuria (OR 0.99 [95% CI 0.94, 1.05]), non-proliferative retinopathy (OR 1.00 (95% CI 0.96, 1.04]) or proliferative retinopathy (OR 1.02 (95% CI 0.95, 1.08]). After excluding individuals with cardiovascular disease and/or antihypertensive medication (n = 418), we found a non-significant association with microalbuminuria (OR 1.04 [95% CI 0.99, 1.10]) and macroalbuminuria (OR 1.05 [95% CI 0.96, 1.16]). The association between dietary salt intake and microalbuminuria was stronger in individuals with a BMI above 25 kg/m(2) (OR 1.11 [95% CI 1.04, 1.18]) than in those with BMI below 25 kg/m(2) (OR 1.03 [95% CI 0.97, 1.09]). No significant associations were found between urinary potassium excretion and microvascular complications.

CONCLUSIONS/INTERPRETATION

In individuals with type 1 diabetes, higher dietary salt intake, as determined by 24 h urinary sodium excretion, may be positively associated with microalbuminuria, particularly in overweight individuals.

The prevalence, characteristics, and clinical significance of abnormal albuminuria in patients with hypertension

Kidney function and cardiovascular disease are closely connected and albuminuria is a proven marker of cardiovascular risk. The present study investigated the prevalence and characteristics of albuminuria in patients with hypertension. Outpatients with essential hypertension under medical treatment were enrolled in this study (n = 350, 70.0 ± 11.4 years old). Urine samples were collected for the measurement of albumin concentration, which are expressed as the ratio of urine albumin to creatinine concentration (mg/g Cr). Cross-sectional analyses were also performed of the relationships between urinary albumin and other variables. Urinary albumin was detected in 88.3% of patients, while only 35.4% showed abnormal albuminuria (≥30 mg/g Cr). The presence of abnormal albuminuria was independently correlated with systolic blood pressure, B-type natriuretic peptide, and C-reactive protein by multivariate analysis (P < 0.05). Furthermore, multivariate regression analysis identified systolic blood pressure, serum creatinine, B-type natriuretic peptide, and C-reactive protein as the only factors showing independent correlation with urinary albumin (P < 0.05). Thus, approximately 35% of hypertensive patients had abnormal albuminuria. Urinary albumin was closely associated with blood pressure, C-reactive protein, and B-type natriuretic peptide, indicating that the severity of albuminuria parallels that of systemic inflammation, cardiac load, and blood pressure.

Weight-loss diets in people with type 2 diabetes and renal disease: a randomized controlled trial of the effect of different dietary protein amounts

BACKGROUND

Higher-protein weight-loss diets (defined as >25% of energy as protein) are not recommended for individuals with type 2 diabetes because of their potential adverse effect on renal function.

OBJECTIVE

We aimed to examine the effect of such diets on renal function over 12 mo in people with type 2 diabetes and early renal disease.

DESIGN

Overweight and obese people with type 2 diabetes were screened to identify those with an albumin:creatinine ratio from 3 to 30 mg/mmol. Seventy-six subjects were randomly assigned to either a moderate-protein weight-loss diet or a standard-protein weight-loss diet for 12 mo. The primary endpoint was the change in renal function as assessed by the isotope glomerular filtration rate (GFR), estimated GFR, and cystatin C. Forty-five subjects (moderate protein: n = 21; standard protein: n = 24) completed the study.

RESULTS

The mean (±SE) weight loss was not different between diets at 9.7 ± 13.4 kg for the moderate-protein diet and 6.6 ± 7.1 kg for the standard-protein diet. There were no changes in renal function or albuminuria or blood pressure, although glycated hemoglobin was lowered with both diets. Changes in renal function were related to the baseline estimated GFR. Patients with stage 1-3 renal disease (<120 mL · min(-1) · 1.73 m(-2); n = 33) had an improvement in renal function, whereas patients with hyperfiltration (>120 mL · min(-1) · 1.73 m(-2); n = 12) had a decrease in the GFR. After adjustment for weight loss, the baseline GFR remained a significant predictor of outcomes with no effect of dietary treatment. An average difference in protein intake between diets of 19 ± 6 g/d was achieved.

CONCLUSION

Weight loss improved renal function, but differences in dietary protein had no effect. This trial was registered at the Australian and New Zealand Clinical Trial Register as ACTRN12608000045314.

The prevalence and characteristics of microalbuminuria in the general population: a cross-sectional study

Background

Microalbuminuria is a marker of cardiovascular events. This study investigated the prevalence of microalbuminuria in the general population and the factors that can affect urinary excretion of albumin.

Methods

Apparently healthy subjects who participated in a health checkup at our hospital were enrolled in this study (n = 7963, male 64.0%, 56.2 ± 11.8 years old) Urine samples were collected for the measurement of albumin concentrations, which were expressed as the ratio of urinary albumin to creatinine concentrations (UACR [mg/g Cr]). Individual salt intake was assessed by estimating the 24-hour urinary salt excretion of subjects.

Results

The mean blood pressure was 124 ± 15/76 ± 10 mmHg and 31.6%, 7.4%, and 44.1% of subjects had hypertension, diabetes mellitus, and dyslipidemia, respectively. Urinary albumin was detected in 7265 subjects (91.2%: UACR ≥ 300 mg/g Cr, 0.5%; 300 > UACR ≥ 30 mg/g Cr, 4.6%; 30 > UACR ≥ 20 mg/g Cr, 2.4%; 20 > UACR ≥ 10 mg/g Cr, 8.7%; 10 > UACR ≥ 5 mg/g Cr, 21.8%; UACR < 5 mg/g Cr, 53.2%). In subjects with detectable albuminuria, UACR was independently correlated with age, systolic blood pressure, serum creatinine, fasting plasma glucose, and salt intake after adjustment for possible factors (P < 0.0001).

Conclusion

The prevalence of microalbuminuria was found to be 4.6% in the general population. The urinary excretion of albumin was closely associated with blood pressure and salt intake. These data indicated the importance of salt restriction for the prevention of cardiovascular disease and end-stage renal disease.

Recent findings on the effects of marine-derived n-3 polyunsaturated fatty acids on urinary albumin excretion and renal function

Albuminuria (this includes microalbuminuria and macroalbuminuria) and reduced glomerular filtration rate are present not only in high-risk populations, but also in the general population. These manifestations of renal disease are associated with an increased risk of cardiovascular disease and may reflect subclinical vascular disease. Long-chain n-3 polyunsaturated fatty acids have been vigorously studied for their potential cardioprotective effects. These fatty acids reduce the levels of serum lipids, blood pressure, inflammation, and endothelial dysfunction, all of which are associated with albuminuria and renal impairment; therefore, marine-derived n-3 fatty acids may potentially play a role in their prevention. This report reviews the recent findings relating marine-derived n-3 fatty acids to urinary albumin excretion and renal function and their risk factors. Although some evidence suggests that marine-derived n-3 fatty acids are associated with a lower incidence of albuminuria in diabetes, there is inadequate evidence supporting their role in glomerular filtration.

Optimal nutrition for predialysis chronic kidney disease

Diet potentially plays a major role in the progression and complications of predialysis CKD. Moderate protein consumption along with a diet low in sodium might slow kidney disease progression. Increasing vegetable protein intake might decrease serum phosphorus, uremic toxins, and kidney damage. Because obesity might be an important factor in the increasing prevalence of CKD, dietary strategies targeting obesity might also benefit CKD progression. In those with more advanced CKD, dietary calcium and phosphorus restriction could minimize vascular calcification. Dietary fiber and vitamin D supplementation might also be important to decrease inflammation in CKD.

Factors affecting levels of urinary albumin excretion in the general population of Spain: the Di@bet.es study

The present study was undertaken to examine the prevalence of urinary ACR (albumin/creatinine ratio) >30 mg/g and the associated clinical and environmental factors in a representative sample of the population of Spain. Di@bet.es study is a national, cross-sectional population-based survey conducted in 2009-2010. Clinical, metabolic, socio-demographic, anthropometric data and information about lifestyle habit were collected. Those subjects without KDM (known diabetes mellitus) were given an OGTT (oral glucose tolerance test). Albumin and creatinine were measured in a urinary sample and ACR was calculated. The population prevalence of ACR >30 mg/g was 7.65% (adjusted for sex and age). The prevalence of ACR >30 mg/g increased with age (P<0.001). Subjects with carbohydrate metabolism disorders had a greater prevalence of ACR >30 mg/g but after being adjusted for age, sex and hypertension, was significant only in those subjects with UKDM (unknown diabetes mellitus) {OR (odd ratio), 2.07 [95% CI (confidence interval), 1.38-3.09]; P<0.001] and KDM [OR, 3.55 (95% CI, 2.63-4.80); P<0.001]. Prevalence of ACR >30 mg/g was associated with hypertension [OR, 1.48 (95% CI, 1.12-1.95); P=0.001], HOMA-IR (homoeostasis model assessment of insulin resistance) [OR, 1.47 (95% CI, 1.13-1.92); P≤0.01], metabolic syndrome [OR, 2.17 (95% CI, 1.72-2.72); P<0.001], smoking [OR, 1.40 (95% CI, 1.06-1.83); P≤0.05], physical activity [OR, 0.68 (95% CI, 0.54-0.88); P≤0.01] and consumption of fish [OR, 0.38 (95% CI, 0.18-0.78); P≤0.01]. This is the first study that reports the prevalence of ACR >30 mg/g in the Spanish population. The association between clinical variables and other potentially modifiable environmental variables contribute jointly, and sometimes interactively, to the explanation of prevalence of ACR >30 mg/g. Many of these risk factors are susceptible to intervention.

Relationship between dietary intake and microalbuminuria: findings from the Takahata study

BACKGROUND

Although several studies have investigated the relationship between dietary nutrient intake and microalbuminuria, no study of an Asian population has been reported. The present study investigates the relationship between dietary intake and microalbuminuria in a general Japanese population.

METHODS

We analyzed 675 men and 924 women who did not have diabetes. Participants who had a urinary albumin-to-creatinine ratio (UACR) ≥300 mg/g, who did not complete a questionnaire regarding food frequency and who did not provide complete urine measurements were excluded. Nutrient intake was assessed by validated food frequency questionnaire. Microalbuminuria was defined as UACR ≥30 mg/g. The relationship between dietary nutrient intake and microalbuminuria was examined using a multiple logistic regression model adjusted for age, total energy intake, body mass index, smoking status, systolic blood pressure and use of antihypertensive medication.

RESULTS

No significant association was observed among the men. The multiple adjusted odds ratios (95% confidence interval) of having microalbuminuria per 1 standard deviation increase in total protein (%kcal), animal protein (%kcal), animal protein (g/day), animal fat, niacin, carbohydrate and β-cryptoxanthin among the women were 1.33 (1.07-1.66), 1.35 (1.09-1.66), 1.42 (1.08-1.88), 1.29 (1.05-1.59), 1.28 (1.04-1.57), 0.73 (0.58-0.92) and 0.76 (0.59-0.996), respectively. The multiple adjusted odds ratio (95% confidence interval) of having microalbuminuria in the highest quintile of n-3 polyunsaturated fatty acids compared with the lowest was 2.16 (1.03-4.54).

CONCLUSION

Less animal protein and more β-cryptoxanthin in the diet might help to prevent microalbuminuria. Prospective studies including controlled trials are required to confirm this conclusion.

Altered dietary salt intake for preventing and treating diabetic kidney disease

BACKGROUND

There is strong evidence that our current consumption of salt is a major factor for increased blood pressure (BP) and a modest reduction in salt intake lowers BP whether BP levels are normal or raised. Tight control of BP in diabetics lowers the risk of strokes, heart attacks and heart failure and slows the progression of diabetic kidney disease (DKD). Currently there is no consensus in restricting salt intake in diabetic patients.

OBJECTIVES

To evaluate the effect of altered salt intake on BP and markers of cardiovascular disease and DKD.

SEARCH STRATEGY

In January 2010, we searched the Cochrane Renal Group's Specialised Register, CENTRAL (in The Cochrane Library), MEDLINE (from 1966) and EMBASE (from 1980) to identify appropriate articles.

SELECTION CRITERIA

We included all randomised controlled trials of salt reduction in individuals with type 1 and type 2 diabetes.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed studies and resolved differences by discussion with a third independent author. We calculated mean effect sizes using both the fixed-effect and random-effects models.

MAIN RESULTS

Thirteen studies (254 individuals) met our inclusion criteria. These included 75 individuals with type 1 diabetes and 158 individuals with type 2 diabetes. The median reduction in urinary sodium was 203 mmol/24 h (11.9 g/day) in type 1 diabetes and 125 mmol/24 h (7.3 g/day) in type 2 diabetes. The median duration of salt restriction was one week in both type 1 and type 2 diabetes. BP was reduced in both type 1 and type 2 diabetes. In type 1 diabetes (56 individuals), salt restriction reduced BP by -7.11/-3.13 mm Hg (systolic/diastolic); 95% CI: systolic BP (SBP) -9.13 to -5.10; diastolic BP (DBP) -4.28 to -1.98). In type 2 diabetes (56 individuals), salt restriction reduced BP by -6.90/-2.87 mm Hg (95% CI: SBP -9.84 to -3.95; DBP -4.39 to -1.35). There was a greater reduction in BP in normotensive patients, possibly due to a larger decrease in salt intake in this group.

AUTHORS' CONCLUSIONS

Although the studies are not extensive, this meta-analysis shows a large fall in BP with salt restriction, similar to that of single drug therapy. All diabetics should consider reducing salt intake at least to less than 5-6 g/day in keeping with current recommendations for the general population and may consider lowering salt intake to lower levels, although further studies are needed.

Cross-sectional association between fish consumption and albuminuria: the European Prospective Investigation of Cancer-Norfolk Study

BACKGROUND

Studies have shown a potential beneficial role for fish and fish oil consumption in the management of diabetes and its complications. The aim of this study is to examine the association between fish consumption and albuminuria in individuals with and without diabetes.

STUDY DESIGN

A cross-sectional analysis conducted in the European Prospective Investigation of Cancer-Norfolk population-based cohort study.

SETTING & PARTICIPANTS

22,384 men and women from general practices in the city of Norwich and vicinity, of whom 517 had diabetes by self-report and 21,867 did not report diabetes.

PREDICTORS

Fish consumption was measured in a validated semiquantitative food frequency questionnaire and categorized as less than 1, 1 to 2, and more than 2 portions/wk. Interaction between fish intake and diabetes status was hypothesized a priori.

OUTCOMES & MEASUREMENTS

Microalbuminuria and macroalbuminuria were defined as urinary albumin-creatinine ratio of 2.5 or greater to 24.9 and 25 mg/mmol or greater, respectively. Log-transformed albumin-creatinine ratio was used as a continuous variable.

RESULTS

Prevalences of microalbuminuria were 22.6% in participants with diabetes and 11.4% in participants without diabetes. Prevalences of macroalbuminuria were 8.3% and 0.6%, respectively. Fish consumption was associated with a lower risk of macroalbuminuria in participants with diabetes (odds ratio, 0.22, >2 versus <1 portion/wk; 95% confidence interval, 0.07 to 0.70; P for trend = 0.009) after adjustment for confounding. This association was not observed in participants with diabetes with microalbuminuria or in the nondiabetic population. There was a significant interaction between diabetes status and fish consumption of 1 to 2 portions/wk (P = 0.03) and more than 2 portions/wk (P = 0.007) for risk of macroalbuminuria.

LIMITATIONS

Cross-sectional nature of study. Self-report of fish intake and diabetes status.

CONCLUSIONS

Greater fish intake was associated with a lower risk of macroalbuminuria in a self-defined diabetic population. These findings merit confirmation in prospective studies and intervention trials and suggest that fish intake may be beneficial for albuminuria in people with diabetes.

Associations between microalbuminuria and animal foods, plant foods, and dietary patterns in the Multiethnic Study of Atherosclerosis

BACKGROUND

The balance between the intake of animal and the intake of plant foods may influence renal vascular integrity as reflected by urinary albumin excretion.

OBJECTIVE

We assessed cross-sectional associations between urinary albumin excretion and dietary patterns and intake of plant and animal foods.

DESIGN

At baseline, diet (food-frequency questionnaire) and the urinary albumin-to-creatinine ratio (ACR; spot urine collection) were measured in 5042 participants in the Multi-Ethnic Study of Atherosclerosis who were aged 45-84 y and were without clinical cardiovascular disease, diabetes, or macroalbuminuria (sex-adjusted ACR >or= 250). We derived dietary patterns by principal components analysis. We also summed food groups to characterize plant food intake (fruit, fruit juice, vegetables, nuts, legumes, whole grains, and refined grains), animal food intake (red meat, processed meat, poultry, fish, high-fat dairy, and low-fat dairy), and nondairy animal food intake.

RESULTS

After adjustment for multiple demographic and lifestyle confounders, a dietary pattern characterized by high consumption of whole grains, fruit, vegetables, and low-fat dairy foods was associated with 20% lower ACR across quintiles (P for trend = 0.004). Neither total animal nor total plant food intake was associated with ACR. However, greater low-fat dairy consumption was associated with 13% lower ACR across quartiles (P for trend = 0.03). Total nondairy animal food consumption was associated with 11% higher ACR across quintiles (P for trend = 0.03).

CONCLUSIONS

A high intake of low-fat dairy foods and a dietary pattern rich in whole grains, fruit, and low-fat dairy foods were both associated with lower ACR. In contrast, collectively, nondairy animal food intake was positively associated with ACR.

Cross-sectional relations of serum aldosterone and urine sodium excretion to urinary albumin excretion in a community-based sample

Experimental models suggest that increased aldosterone and sodium intake are associated with renovascular damage and resultant proteinuria. We hypothesized that serum aldosterone and urinary sodium would be associated with urinary albumin excretion, an indicator of kidney damage. We evaluated 2700 participants (53% women, mean age 58 years) from the Framingham Offspring Study who attended a routine examination between 1995 and 1998, who were free of heart failure and renal failure, and underwent testing for serum aldosterone, spot urinary sodium, and urinary albumin excretion (urine albumin/creatinine ratio, UACR), the latter two indexed to urinary creatinine. Stepwise multivariable linear regression was used to evaluate the relations between UACR with urinary sodium index and serum aldosterone. In multivariable regression, log urinary sodium index was associated positively with log-UACR (P<0.0001). UACR levels in the fourth and fifth quintiles of urinary sodium index were 24% (95% confidence interval (CI) 3-49%), and twofold higher (95% CI 72-150%), respectively, relative to the lowest quintile (P-value for trend across quintiles <0.001). In multivariable models, log-transformed aldosterone was not related to log-UACR. The top quintile of serum aldosterone levels was associated with a 21% higher (95% 1-44%) UACR levels relative to the lowest quintile. Urinary albumin excretion was strongly and positively associated in a continuous fashion with urinary sodium excretion, whereas a weaker nonlinear positive relation with serum aldosterone was noted. Our cross-sectional observations raise the possibility that dietary salt intake may be associated with early renovascular damage.