Sugary soda consumption and albuminuria: results from the National Health and Nutrition Examination Survey, 1999-2004

Adherence to a healthful plant-based diet and risk of mortality among individuals with chronic kidney disease: A prospective cohort study

BACKGROUND

Plant-rich dietary patterns may protect against negative health outcomes among individuals with chronic kidney disease (CKD), although aspects of plant-based diet quality have not been studied. This study aimed to examine associations between healthful and unhealthful plant-based dietary patterns with risk of all-cause mortality among CKD patients for the first time.

METHODS

This prospective analysis included 4807 UK Biobank participants with CKD at baseline. We examined associations of adherence to both the healthful plant-based diet index (hPDI) and unhealthful plant-based diet index (uPDI), calculated from repeated 24-h dietary assessments, with risk of all-cause mortality using multivariable Cox proportional hazard regression models.

RESULTS

Over a 10-year follow-up, 675 deaths were recorded. Participants with the highest hPDI scores showed a 34% lower risk of mortality [HRQ4vsQ1 (95% CI): 0.66 (0.52-0.83), ptrend <0.001]. Those with the highest uPDI scores had a 52% [1.52 (1.20-1.93), ptrend = 0.002] higher risk of mortality compared to participants with the lowest respective scores. In food group-specific analyses, higher wholegrain intakes were associated with a 29% lower mortality risk, while intakes of refined grains, and sugar-sweetened beverages were associated a 30% and 34% higher risk, respectively.

CONCLUSIONS

In CKD patients, a higher intake of healthy plant-based foods was associated with a lower risk of mortality, while a higher intake of less healthy plant-based foods was associated with a higher risk of mortality. These results underscore the importance of plant food quality and support the potential role of healthy plant food consumption in the treatment and management of CKD to mitigate unfavourable outcomes.

Glycemic index of a nutritional supplement designed for people with chronic kidney disease

The study was carried out to measure the glycemic index (GI) of an oral food supplement for people with CKD as well as on patients on maintenance dialysis. The study was conducted as per international protocols for testing GI, was approved by the local institutional ethics committee, and was registered with the Clinical Trial Registry of India (CTRI). This was a crossover randomized controlled study which enrolled 15 participants between the ages of 18 and 45 years. The participants were randomly allotted to one group that consumed either the reference food (27.5 g of glucose monohydrate) or 118 g of the nutritional supplement which contained 25 g of available carbohydrates. Fasting capillary blood samples as well as blood samples at different time intervals as per the GI protocol, after consumption of either the supplement or the reference food were taken from the participants. Each testing day was separated by a 3-day washout period. GI was calculated from the incremental area under the blood glucose response elicited by the nutritional supplement as a percentage of the response after the consumption of 25 g of glucose (27.5 g of glucose monohydrate) by the same participant using a standard formula. The GI of the nutritional supplement was calculated to be 10.3 ± 2.0 which is considered to be low as per international GI testing standards. The product was created to supplement the diet of people with CKD at different stages and to help prevent the progression from CKD to ESRD as well as the risk for CVD. This product was found to have a low GI which is desirable for people with CKD as well as diabetics in general who are at risk for developing CKD.

Impacts of High Fructose Diet and Chronic Exercise on Nitric Oxide Synthase and Oxidative Stress in Rat Kidney

Chronic exercise (Ex) exerts antihypertensive and renoprotective effects in rats fed a high fructose diet (HFr). To elucidate the mechanisms, the impacts of an HFr and Ex on the nitric oxide (NO) system and oxidative stress in the kidney were examined. Rats were fed a control diet or an HFr, and a part of the HFr-fed rats underwent treadmill running for 12 weeks. The HFr did not affect nitrate/nitrite (NO_x) levels in plasma and urine, and Ex increased the NO_x levels. The HFr increased thiobarbituric acid reactive substance (TBARS) levels in plasma and urine, and Ex decreased the HFr-increased TBARS levels in plasma. The HFr increased the neuronal and endothelial NO synthase (nNOS and eNOS) expressions, and Ex enhanced the HFr-increased eNOS expression. The HFr inhibited the eNOS phosphorylation at serine 1177, and Ex restored the HFr-inhibited eNOS phosphorylation. The HFr increased xanthine oxidase and NADPH oxidase activities, and Ex restored the HFr-increased xanthine oxidase activity but enhanced the HFr-increased NADPH oxidase activity. The HFr increased the nitrotyrosine levels, and Ex attenuated the HFr-increased levels. These results indicate that although Ex enhances the HFr-increased eNOS expression and NADPH oxidase activity, an HFr inhibits renal eNOS phosphorylation and NO bioavailability, whereas Ex ameliorates them.

High Fructose Corn Syrup Accelerates Kidney Disease and Mortality in Obese Mice with Metabolic Syndrome

The presence of obesity and metabolic syndrome is strongly linked with chronic kidney disease (CKD), but the mechanisms responsible for the association are poorly understood. Here, we tested the hypothesis that mice with obesity and metabolic syndrome might have increased susceptibility to CKD from liquid high fructose corn syrup (HFCS) by favoring the absorption and utilization of fructose. We evaluated the pound mouse model of metabolic syndrome to determine if it showed baseline differences in fructose transport and metabolism and whether it was more susceptible to chronic kidney disease when administered HFCS. Pound mice have increased expression of fructose transporter (Glut5) and fructokinase (the limiting enzyme driving fructose metabolism) associated with enhanced fructose absorption. Pound mice receiving HFCS rapidly develop CKD with increased mortality rates associated with intrarenal mitochondria loss and oxidative stress. In pound mice lacking fructokinase, the effect of HFCS to cause CKD and early mortality was aborted, associated with reductions in oxidative stress and fewer mitochondria loss. Obesity and metabolic syndrome show increased susceptibility to fructose-containing sugars and increased risk for CKD and mortality. Lowering added sugar intake may be beneficial in reducing the risk for CKD in subjects with metabolic syndrome.

ChREBP-β/TXNIP aggravates frucose-induced renal injury through triggering ferroptosis of renal tubular epithelial cells

High fructose intake is an essential risk factor for kidney injury. However, the specific mechanism underlying high fructose-induced kidney injury remains unclarified. Carbohydrate response element-binding protein (ChREBP) is a key transcriptional activator that regulates fructose metabolism. ChREBP-β exhibits sustained activity due to the lack of a low glucose inhibitory domain, and is thus described as the active form of ChREBP. In this study, a mouse model with specific overexpression of ChREBP-β in the renal tubule was established by using the Cre/LoxP method. Quantitative proteomic analysis and experimental verification results suggest that ChREP-β overexpression leads to ferroptosis of renal tubular epithelial cells and kidney injury. ChREPB-β promotes the gene transcription of thioredoxin-interacting protein (TXNIP) and thereby increases its expression level. TXNIP is associated with activation of ferroptosis. TXNIP can initiate ferroptosis and eventually contribute to high fructose-induced renal tubular epithelial cell damage. Through down-regulating ChREBP-β, metformin can inhibit gene transcription of TXNIP, attenuate high fructose-induced ferroptosis in renal tubular epithelial cells, and alleviate kidney injury. In conclusion, ChREBP-β mediates fructose-induced ferroptosis of renal tubular epithelial cells, and metformin with a ChREBP-β inhibitory effect may be a potential treatment for ferroptosis of renal tubular epithelial cells.

Dietary Fructose and Fructose-Induced Pathologies

The consumption of fructose as sugar and high-fructose corn syrup has markedly increased during the past several decades. This trend coincides with the exponential rise of metabolic diseases, including obesity, nonalcoholic fatty liver disease, cardiovascular disease, and diabetes. While the biochemical pathways of fructose metabolism were elucidated in the early 1990s, organismal-level fructose metabolism and its whole-body pathophysiological impacts have been only recently investigated. In this review, we discuss the history of fructose consumption, biochemical and molecular pathways involved in fructose metabolism in different organs and gut microbiota, the role of fructose in the pathogenesis of metabolic diseases, and the remaining questions to treat such diseases.

Renal Tubular Handling of Glucose and Fructose in Health and Disease

The proximal tubule of the kidney is programmed to reabsorb all filtered glucose and fructose. Glucose is taken up by apical sodium-glucose cotransporters SGLT2 and SGLT1 whereas SGLT5 and potentially SGLT4 and GLUT5 have been implicated in apical fructose uptake. The glucose taken up by the proximal tubule is typically not metabolized but leaves via the basolateral facilitative glucose transporter GLUT2 and is returned to the systemic circulation or used as an energy source by distal tubular segments after basolateral uptake via GLUT1. The proximal tubule generates new glucose in metabolic acidosis and the postabsorptive phase, and fructose serves as an important substrate. In fact, under physiological conditions and intake, fructose taken up by proximal tubules is primarily utilized for gluconeogenesis. In the diabetic kidney, glucose is retained and gluconeogenesis enhanced, the latter in part driven by fructose. This is maladaptive as it sustains hyperglycemia. Moreover, renal glucose retention is coupled to sodium retention through SGLT2 and SGLT1, which induces secondary deleterious effects. SGLT2 inhibitors are new anti-hyperglycemic drugs that can protect the kidneys and heart from failing independent of kidney function and diabetes. Dietary excess of fructose also induces tubular injury. This can be magnified by kidney formation of fructose under pathological conditions. Fructose metabolism is linked to urate formation, which partially accounts for fructose-induced tubular injury, inflammation, and hemodynamic alterations. Fructose metabolism favors glycolysis over mitochondrial respiration as urate suppresses aconitase in the tricarboxylic acid cycle, and has been linked to potentially detrimental aerobic glycolysis (Warburg effect). © 2022 American Physiological Society. Compr Physiol 12:2995-3044, 2022.

Sugar-sweetened beverage consumption and mortality of chronic kidney disease: results from the US National Health and Nutrition Examination Survey, 1999–2014

Background

The relationship between intake of sugar-sweetened beverages (SSBs) and the risk of death in patients with chronic kidney disease (CKD) is unclear. We evaluated the association between SSB intake and subsequent overall mortality in CKD patients.

Methods

We included data from 3996 CKD patients who participated in the 1999–2014 National Health and Nutrition Examination Survey (NHANES). SSB intake was assessed by a 24-h dietary recall, grouped as none, >0 to <1 serving/day, 1 to <2 servings/day and ≥2 servings/day. After adjusting for demographic variables, lifestyle, diet and comorbidities, Cox proportional risk regressions were applied to analyze the associations between the daily intake of SSBs as well as added sugar from beverages and all-cause mortality.

Results

In the whole research population, the median age at baseline was 67 years, 22% were Black and 54% were female. A total of 42% had stage 3 CKD. During an average follow-up period of 8.3 years, a sum of 1137 (28%) deaths from all causes was recorded. The confounder-adjusted risk of mortality was associated with an increase of 1 serving/day of SSBs, with all-cause mortality of 1.18 [95% confidence interval (95% CI)1.08–1.28], and intakes of increased 20-g added sugar/1000 kcal of total energy per day were associated with all-cause mortality of 1.14 (1.05–1.24). Equivalently substituting 1 serving/day of SSBs with unsweetened coffee [HR (95% CI) 0.82 (0.74–0.91)], unsweetened tea [HR (95% CI) 0.86 (0.76–0.98)], plain water [HR (95% CI) 0.79 (0.71–0.88)], or non- or low-fat milk [HR (95% CI) 0.75 (0.60–0.93)] were related to a 14–25% reduced risk of all-cause mortality.

Conclusion

Findings suggest that in the CKD population, increased SSB intake was associated with a higher risk of mortality and indicated a stratified association with dose. Plain water and unsweetened coffee/tea might be possible alternatives for SSBs to avert untimely deaths.

Impact of water consumption on renal function in the general population: a cross-sectional analysis of KNHANES data (2008-2017)

BACKGROUND

The renoprotective effect of water intake remains unclear. We aimed to investigate the relationship between water intake and renal impairment in the Korean general population, focusing on individual differences in body fluid distribution and risk of chronic dehydration.

METHODS

We conducted a cross-sectional analysis of the 2008-2017 Korea National Health and Nutrition Examination Survey (KNHANES). Adult participants who had body weight and serum creatinine data and had answered 24-h recall nutritional survey were included. Four water intake groups were defined by daily total water intake per body weight: lowest (< 20 mL/kg/day), low-moderate (20-29.9 mL/kg/day), high-moderate (30-49.9 mL/kg/day), and highest (≥ 50 mL/kg/day). We assessed the risk of renal impairment (estimated glomerular filtration rate ≤ 60 mL/min/1.73 m2) according to water intake.

RESULTS

In total of 50,113 participants, 3.9% had renal impairment. The risk of renal impairment gradually decreased as water intake increased. After adjustment of sodium intake, the trend of renoprotective effect was remained in low-moderate and high-moderate water intake group compared to low intake group, whereas no significant impact was observed with the highest water intake due to concurrent intake of high sodium. In subgroup analysis, the renoprotective effect of water intake was significant in the participants with elderly, male and daily sodium intake over 2 g/day.

CONCLUSIONS

High daily water intake is renoprotective. Our data may provide an important basis for determining the amount of water intake needed to prevent renal impairment, considering variations in body weight, body composition and risk of chronic dehydration.

Prevalence and cardiometabolic correlates of ketohexokinase gene variants among UK Biobank participants

Essential fructosuria (EF) is a benign, asymptomatic, autosomal recessive condition caused by loss-of-function variants in the ketohexokinase gene and characterized by intermittent appearance of fructose in the urine. Despite a basic understanding of the genetic and molecular basis of EF, relatively little is known about the long-term clinical consequences of ketohexokinase gene variants. We examined the frequency of ketohexokinase variants in the UK Biobank sample and compared the cardiometabolic profiles of groups of individuals with and without these variants alone or in combination. Study cohorts consisted of groups of participants defined based on the presence of one or more of the five ketohexokinase gene variants tested for in the Affymetrix assays used by the UK Biobank. The rs2304681:G>A (p.Val49Ile) variant was present on more than one-third (36.8%) of chromosomes; other variant alleles were rare (<1%). No participants with the compound heterozygous genotype present in subjects exhibiting the EF phenotype in the literature (Gly40Arg/Ala43Thr) were identified. The rs2304681:G>A (p.Val49Ile), rs41288797 (p.Val188Met), and rs114353144 (p.Val264Ile) variants were more common in white versus non-white participants. Otherwise, few statistically or clinically significant differences were observed after adjustment for multiple comparisons. These findings reinforce the current understanding of EF as a rare, benign, autosomal recessive condition.

Sugar- and artificially-sweetened beverages and the risks of chronic kidney disease: a systematic review and dose-response meta-analysis

BACKGROUND

Consumption of sugar or artificially-sweetened beverages (SASBs) has been linked to albuminuria, decline in kidney function, and risk of chronic kidney disease (CKD). However, the results are controversial. We therefore aim to evaluate the effects of sugar or artificially-sweetened beverage consumption on CKD risk.

METHODS

Original observational studies reporting relative risks (RRs) with 95% confidence intervals (CIs) for the association between sugar or artificially-sweetened beverage consumption and impaired renal function or CKD risk in adults were identified using a systematic search of PubMed and EMBASE from inception to 20 February, 2019. Random effects model was applied to derive summary RRs and 95% CIs. Linear and non-linear dose-response relationships were estimated using data from sugar or artificially-sweetened beverage consumption categories in each study.

RESULTS

The summary RR of CKD for high versus low sugar-sweetened beverage consumption was 1.30 (95% CI 0.88-1.94) according to six included studies with a total of 25,455 participants, while the pooled RR of CKD for high versus low artificially sweetened beverage consumption was 1.40 (95% CI 0.65-3.02) according to three studies with a total of 19,995 participants. For dose-response analysis, a significant, increased risk of CKD was observed with the sugar or artificially-sweetened beverage consumption above seven servings per week (P < 0.001).

CONCLUSION

Our study found a positive association between consumption of sugar or artificially-sweetened beverage consumption and CKD, though it did not reach statistical significance. However, the dose-response results suggest that more than seven servings per week should be avoided.

Association of self-reported moderate vegetable juice intake with small decline in kidney function in a five-year prospective study

OBJECTIVES

Although consumption of vegetable and 100% fruit juices are an acceptable alternative for vegetable and fruit intake, information about their actual effects on kidney function is sparse. The aim of this study was to determine the association between the consumption of vegetable and fruit juices and changes in kidney function in a Japanese population over a 5-y period.

METHODS

In this prospective study, we analyzed 2755 Japanese (742 men and 2013 women) individuals who participated in both the baseline and follow-up surveys in the Daiko study (a study within the Japan Multi-Institutional Collaborative Cohort study). Estimated glomerular filtration rate (eGFR) was calculated by age, sex, and serum creatinine level. For each beverage, we categorized all participants into four groups-rare (rarely consumed), low (≤2 cups/wk), moderate (3-4 cups/wk), or frequent (≥5 cups/wk) consumers of the beverage-based on a food frequency questionnaire.

RESULTS

The mean baseline and follow-up eGFR (SD) were 82.4 (14.6) and 72.2 (12.6), respectively. In fully adjusted regression analyses, moderate consumption of vegetable juice was associated a lower decline in eGFR compared with the rare consumption group (β = -1.30; P = 0.01). Moreover, stratified analyses revealed that this significant association remained in those who were young, female, non-obese, normotensive, smoked cigarettes, consumed alcohol, or exercised. However, no significant association was found in analyses for fruit juices.

CONCLUSIONS

This 5-y prospective study suggested an association between self-reported moderate consumption of vegetable juice and changes (possibly smaller decline) in kidney function in a relatively healthy Japanese population.

Hyperuricemia in Kidney Disease: A Major Risk Factor for Cardiovascular Events, Vascular Calcification, and Renal Damage

Kidney disease, especially when it is associated with a reduction in estimated glomerular filtration rate, can be associated with an increase in serum urate (uric acid), suggesting that hyperuricemia in subjects with kidney disease may be a strictly secondary phenomenon. Mendelian randomization studies that evaluate genetic scores regulating serum urate also generally have not found evidence that serum urate is a causal risk factor in chronic kidney disease. Nevertheless, this is countered by a large number of epidemiologic, experimental, and clinical studies that have suggested a potentially important role for uric acid in kidney disease and cardiovascular disease. Here, we review the topic in detail. Overall, the studies strongly suggest that hyperuricemia does have an important pathogenic role that likely is driven by intracellular urate levels. An exception may be the role of extracellular uric acid in atherosclerosis and vascular calcification. One of the more striking findings on reviewing the literature is that the primary benefit of lowering serum urate in subjects with CKD is not by slowing the progression of renal disease, but rather by reducing the incidence of cardiovascular events and mortality. We recommend large-scale clinical trials to determine if there is a benefit in lowering serum urate in hyperuricemic subjects in acute and chronic kidney disease and in the reduction of cardiovascular morbidity and mortality in subjects with end-stage chronic kidney disease.

Tissue-Specific Fructose Metabolism in Obesity and Diabetes

PURPOSE OF REVIEW

The objective of this review is to provide up-to-date and comprehensive discussion of tissue-specific fructose metabolism in the context of diabetes, dyslipidemia, and nonalcoholic fatty liver disease (NAFLD).

RECENT FINDINGS

Increased intake of dietary fructose is a risk factor for a myriad of metabolic complications. Tissue-specific fructose metabolism has not been well delineated in terms of its contribution to detrimental health effects associated with fructose intake. Since inhibitors targeting fructose metabolism are being developed for the management of NAFLD and diabetes, it is essential to recognize how inability of one tissue to metabolize fructose may affect metabolism in the other tissues. The primary sites of fructose metabolism are the liver, intestine, and kidney. Skeletal muscle and adipose tissue can also metabolize a large portion of fructose load, especially in the setting of ketohexokinase deficiency, the rate-limiting enzyme of fructose metabolism. Fructose can also be sensed by the pancreas and the brain, where it can influence essential functions involved in energy homeostasis. Lastly, fructose is metabolized by the testes, red blood cells, and lens of the eye where it may contribute to infertility, advanced glycation end products, and cataracts, respectively. An increase in sugar intake, particularly fructose, has been associated with the development of obesity and its complications. Inhibition of fructose utilization in tissues primary responsible for its metabolism alters consumption in other tissues, which have not been traditionally regarded as important depots of fructose metabolism.

Fructose and Uric Acid: Major Mediators of Cardiovascular Disease Risk Starting at Pediatric Age

Recently, there has been a growing interest in epidemiological and clinical studies supporting a pathogenetic role of fructose in cardio-metabolic diseases, especially in children and adolescents. In the present review, we summarize experimental data on the potential biological mechanisms linking fructose and uric acid in the development of insulin resistance, metabolic syndrome, obesity, diabetes, hypertension, non-alcoholic fatty liver disease and chronic renal disease, thereby contributing to an increase in cardiovascular risk at pediatric age.

Vitamin A deficiency increases the oleic acid (C18:1) levels in the kidney of high fructose diet-fed rats

Background & objectives

Stearoyl-CoA desaturase 1 (SCD1) is a key lipogenic enzyme responsible for endogenous synthesis of monounsaturated fatty acids (MUFA) and plays a key role in various pathophysiology, including fatty liver diseases. In this experimental study the impact of vitamin A deficiency was assessed on SCD1 regulation in relation to kidney biology, under high fructose (HFr) diet-fed condition in rats.

Methods

Forty male weanling (21 day old) Wistar rats were divided into four groups control, vitamin A-deficient (VAD), HFr, VAD with HFr consisting of eight rats each, except 16 for the VAD group. The groups received one of the following diets: control, VAD, HFr and VAD with HFr for 16 wk, except half of the VAD diet-fed rats were shifted to HFr diet, after eight week period.

Results

Feeding of VAD diet (alone or with HFr) significantly reduced the kidney retinol (0.51, 0.44 μg/g vs. 2.1 μg/g; P < 0.05), while increased oleic (C18:1) and total MUFA levels (23.3, 22.2% and 27.3, 25.4% respectively vs. 14.7 and 16.6%; P < 0.05) without affecting the SCD1, both at protein and mRNA levels, when compared with HFr. Comparable, immunohistological staining for SCD1 was observed in the distal convoluted tubules. Despite an increase in MUFA, morphology, triglyceride content and markers of kidney function were not affected by VAD diet feeding.

Interpretation & conclusions

Feeding of VAD diet either alone or under HFr condition increased the kidney oleic acid (C18:1) levels and thus total MUFA, which corroborated with elevated SCD1 activity index, without affecting its expression status. However, these changes did not alter the kidney morphology and function. Thus, nutrient-gene regulation in kidney biology seems to be divergent.

Fructose Production and Metabolism in the Kidney

Understanding fructose metabolism might provide insights to renal pathophysiology. To support systemic glucose concentration, the proximal tubular cells reabsorb fructose as a substrate for gluconeogenesis. However, in instances when fructose intake is excessive, fructose metabolism is costly, resulting in energy depletion, uric acid generation, inflammation, and fibrosis in the kidney. A recent scientific advance is the discovery that fructose can be endogenously produced from glucose under pathologic conditions, not only in kidney diseases, but also in diabetes, in cardiac hypertrophy, and with dehydration. Why humans have such a deleterious mechanism to produce fructose is unknown, but it may relate to an evolutionary benefit in the past. In this article, we aim to illuminate the roles of fructose as it relates to gluconeogenesis and fructoneogenesis in the kidney.

Diet-Induced Rodent Models of Diabetic Peripheral Neuropathy, Retinopathy and Nephropathy

Unhealthy dietary habits are major modifiable risk factors for the development of type 2 diabetes mellitus, a metabolic disease with increasing prevalence and serious consequences. Microvascular complications of diabetes, namely diabetic peripheral neuropathy (DPN), retinopathy (DR), and nephropathy (DN), are associated with high morbidity rates and a heavy social and economic burden. Currently, available therapeutic options to counter the evolution of diabetic microvascular complications are clearly insufficient, which strongly recommends further research. Animal models are essential tools to dissect the molecular mechanisms underlying disease progression, to unravel new therapeutic targets, as well as to evaluate the efficacy of new drugs and/or novel therapeutic approaches. However, choosing the best animal model is challenging due to the large number of factors that need to be considered. This is particularly relevant for models induced by dietary modifications, which vary markedly in terms of macronutrient composition. In this article, we revisit the rodent models of diet-induced DPN, DR, and DN, critically comparing the main features of these microvascular complications in humans and the criteria for their diagnosis with the parameters that have been used in preclinical research using rodent models, considering the possible need for factors which can accelerate or aggravate these conditions.

Glycation With Fructose: The Bitter Side of Nature's Own Sweetener

Fructose is a ketohexose and sweetest among all the natural sugars. Like other reducing sugars, it reacts readily with the amino- and nucleophilic groups of proteins, nucleic acids and other biomolecules resulting in glycation reactions. The non-enzymatic glycation reactions comprise Schiff base formation, their Amadori rearrangement followed by complex and partly incompletely understood reactions culminating in the formation of Advance Glycation End products (AGEs). The AGEs are implicated in complications associated with diabetes, cardiovascular disorders, Parkinson's disease, etc. Fructose is highly reactive and forms glycation products that differ both in structure and reactivity as compared to those formed from glucose. Nearly all tissues of higher organisms utilize fructose but only a few like the ocular lens, peripheral nerves erythrocytes and testis have polyol pathway active for the synthesis of fructose. Fructose levels rarely exceed those of glucose but, in tissues that operate the polyol pathway, its concentration may rise remarkably during diabetes and related disorders. Diet contributes significantly to the body fructose levels however, availability of technologies for the large scale and inexpensive production of fructose, popularity of high fructose syrups as well as the promotion of vegetarianism have resulted in a remarkable increase in the consumption of fructose. In vivo glycation reactions by fructose, therefore, assume remarkable significance. The review, therefore, aims to highlight the uniqueness of glycation reactions with fructose and its role in some pathophysiological situations.

Sleep debt and prevalence of proteinuria in subjects with short sleep duration on weekdays: a cross-sectional study

STUDY OBJECTIVE

Short sleep duration is a risk factor of chronic kidney disease, along with cardiovascular diseases and all-cause mortality. Several studies reported that many people sleep longer on weekends than on weekdays, suggesting that they should be compensated for their sleep debt on weekdays on the weekends. Few studies have reported the clinical impact of sleep debt on the kidney.

METHODS

This cross-sectional study included 5799 employees of Osaka University who visited its Health Care Center for their annual health examinations and answered ≤ 6 h of sleep duration on weekdays. The independent variable was the sleep debt index defined as a gap in self-reported sleep duration (≤ 5, 5-6, 6-7, 7-8, 8-9, and ≥ 9 h) between weekdays and weekends, which was categorized into ≤ 0, + 1, + 2, + 3 and ≥+4. An association between the sleep debt index and a prevalence of proteinuria defined as dipstick proteinuria of ≥ 1 + was assessed using logistic regression models adjusting for clinically relevant factors.

RESULTS

More than four-fifths of the subjects had a positive sleep debt index (≤ 0, + 1, + 2, + 3, and ≥+4 recorded for 19%, 36%, 28%, 11%, and 6%, respectively). The multivariable-adjusted logistic regression models showed the sleep debt index ≥ 3 + was significantly associated with the prevalence of proteinuria (sleep debt index ≤ 0, adjusted odds ratio 1.13 [0.77, 1.65]; + 1, 1.00 [reference]; + 2, 1.29 [0.93, 1.79]; + 3, 1.54 [1.02, 2.33]; ≥ + 4, 1.87 [1.15, 3.05]).

CONCLUSIONS

Sleep debt was associated with the prevalence of proteinuria in a dose-dependent manner.

Beware Energy Drinks: A Case of a Toxic Triad Syndrome in a Diabetic Patient With Nonalcoholic Fatty Liver Disease

Energy drinks are widely used and very popular. They are touted as "harmless" energy boosters for use in professional, recreational and domestic settings. They are typically high in monosaccharides, and caffeine with other assorted products like ginseng. Careful study of the potential risks of their use is nonexistent while rigorous documentation of their touted energy boosting capacity is also meagre. We present the cautionary case of a 46-year-old Caucasian man with well-controlled type 2 diabetes and nonalcoholic fatty liver disease who developed a toxic triad syndrome of gastritis, hepatitis and pancreatitis within 4 months of commencing daily consumption of 2-3 160z cans of the energy drink Monster Energy. His clinical symptoms and biochemical derangements promptly resolved with stopping the beverage. We discuss the potential risks inherent in unsupervised liberal consumption of energy drinks and the need for both caution and vigilance among clinicians and patients.

Pediatric Thermoregulation: Considerations in the Face of Global Climate Change

Predicted global climate change, including rising average temperatures, increasing airborne pollution, and ultraviolet radiation exposure, presents multiple environmental stressors contributing to increased morbidity and mortality. Extreme temperatures and more frequent and severe heat events will increase the risk of heat-related illness and associated complications in vulnerable populations, including infants and children. Historically, children have been viewed to possess inferior thermoregulatory capabilities, owing to lower sweat rates and higher core temperature responses compared to adults. Accumulating evidence counters this notion, with limited child-adult differences in thermoregulation evident during mild and moderate heat exposure, with increased risk of heat illness only at environmental extremes. In the context of predicted global climate change, extreme environmental temperatures will be encountered more frequently, placing children at increased risk. Thermoregulatory and overall physiological strain in high temperatures may be further exacerbated by exposure to/presence of physiological and environmental stressors including pollution, ultraviolet radiation, obesity, diabetes, associated comorbidities, and polypharmacy that are more commonly occurring at younger ages. The aim of this review is to revisit fundamental differences in child-adult thermoregulation in the face of these multifaceted climate challenges, address emerging concerns, and emphasize risk reduction strategies for the health and performance of children in the heat.

Patterns of Beverages Consumed and Risk of Incident Kidney Disease

BACKGROUND AND OBJECTIVES

Selected beverages, such as sugar-sweetened beverages, have been reported to influence kidney disease risk, although previous studies have been inconsistent. Further research is necessary to comprehensively evaluate all types of beverages in association with CKD risk to better inform dietary guidelines.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted a prospective analysis in the Jackson Heart Study, a cohort of black men and women in Jackson, Mississippi. Beverage intake was assessed using a food frequency questionnaire administered at baseline (2000-2004). Incident CKD was defined as onset of eGFR<60 ml/min per 1.73 m² and ≥30% eGFR decline at follow-up (2009-13) relative to baseline among those with baseline eGFR ≥60 ml/min per 1.73 m². Logistic regression was used to estimate the association between the consumption of each individual beverage, beverage patterns, and incident CKD. Beverage patterns were empirically derived using principal components analysis, in which components were created on the basis of the linear combinations of beverages consumed.

RESULTS

Among 3003 participants, 185 (6%) developed incident CKD over a median follow-up of 8 years. At baseline, mean age was 54 (SD 12) years, 64% were women, and mean eGFR was 98 (SD 18) ml/min per 1.73 m². After adjusting for total energy intake, age, sex, education, body mass index, smoking, physical activity, hypertension, diabetes, HDL cholesterol, LDL cholesterol, history of cardiovascular disease, and baseline eGFR, a principal components analysis-derived beverage pattern consisting of higher consumption of soda, sweetened fruit drinks, and water was associated with significantly greater odds of incident CKD (odds ratio tertile 3 versus 1 =1.61; 95% confidence interval, 1.07 to 2.41).

CONCLUSIONS

Higher consumption of sugar-sweetened beverages was associated with an elevated risk of subsequent CKD in this community-based cohort of black Americans.

A Higher Fructose Intake Is Associated with Greater Albuminuria in Subjects with Type 2 Diabetes Mellitus

The aim of this single center cross-sectional study was to investigate the association between fructose intake and albuminuria in subjects with type 2 diabetes mellitus (T2DM). This is a single center cross-sectional study. One hundred and forty-three subjects with T2DM were recruited from the Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran. The median daily fructose intake was estimated with a prospective food registry during 3 days (2 week-days and one weekend day) and they were divided into low fructose intake (<25 g/day) and high fructose intake (≥ 25 g/day). Complete clinical and biochemical evaluations were performed, including anthropometric variables and a 24-hour urine collection for albuminuria determination. One hundred and thirty-six subjects were analyzed in this study. We found a positive significant association between daily fructose intake and albuminuria (ρ= 0.178, p=0.038) in subjects with type 2 diabetes mellitus. Other variables significantly associated with albuminuria were body mass index (BMI) (ρ= 0.170, p=0.048), mean arterial pressure (MAP) (ρ= 0.280, p=0.001), glycated hemoglobin (A1c) (ρ= 0.197, p=0.022), and triglycerides (ρ= 0.219, p=0.010). After adjustment for confounding variables we found a significant and independent association between fructose intake and albuminuria (β= 13.96, p=0.006). We found a statistically significant higher albuminuria (60.8 [12.8-228.5] versus 232.2 [27.2-1273.0] mg/day, p 0.002), glycated hemoglobin (8.6±1.61 versus 9.6±2.1 %), p= 0.003, and uric acid (6.27±1.8 versus 7.2±1.5 mg/dL), p=0.012, in the group of high fructose intake versus the group with low fructose intake, and a statistically significant lower creatinine clearance (76.5±30.98 mL/min versus 94.9±36.8, p=0.014) in the group with high fructose intake versus the group with low fructose intake. In summary we found that a higher fructose intake is associated with greater albuminuria in subjects with T2DM.

Fructose increases risk for kidney stones: potential role in metabolic syndrome and heat stress

Background

Fructose intake, mainly as table sugar or high fructose corn syrup, has increased in recent decades and is associated with increased risk for kidney stones. We hypothesized that fructose intake alters serum and urinary components involved in stone formation.

Methods

We analyzed a previously published randomized controlled study that included 33 healthy male adults (40–65 years of age) who ingested 200 g of fructose (supplied in a 2-L volume of 10% fructose in water) daily for 2 weeks. Participants were evaluated at the Unit of Nephrology of the Mateo Orfila Hospital in Menorca. Changes in serum levels of magnesium, calcium, uric acid, phosphorus, vitamin D, and intact PTH levels were evaluated. Urine magnesium, calcium, uric acid, phosphorus, citrate, oxalate, sodium, potassium, as well as urinary pH, were measured.

Results

Ingestion of fructose was associated with an increased serum level of uric acid (p < 0.001), a decrease in serum ionized calcium (p = 0.003) with a mild increase in PTH (p < 0.05) and a drop in urinary pH (p = 0.02), an increase in urine oxalate (p = 0.016) and decrease in urinary magnesium (p = 0.003).

Conclusions

Fructose appears to increase urinary stone formation in part via effects on urate metabolism and urinary pH, and also via effects on oxalate. Fructose may be a contributing factor for the development of kidney stones in subjects with metabolic syndrome and those suffering from heat stress.

Trial registration

ClinicalTrials.gov NCT00639756 March 20, 2008.

High fructose diet feeding accelerates diabetic nephropathy in Spontaneously Diabetic Torii (SDT) rats

Diabetic nephropathy (DN) is one of the complications of diabetes and is now the most common cause of end-stage renal disease. Fructose is a simple carbohydrate that is present in fruits and honey and is used as a sweetener because of its sweet taste. Fructose has been reported to have the potential to progress diabetes and DN in humans even though fructose itself does not increase postprandial plasma glucose levels. In this study, we investigated the effects of high fructose intake on the kidney of the Spontaneously Diabetic Torii (SDT) rats which have renal lesions similar to those in DN patients and compared these with the effects in normal SD rats. This study revealed that a 4-week feeding of the high fructose diet increased urinary excretion of kidney injury makers for tubular injury and accelerated mainly renal tubular and interstitial lesions in the SDT rats but not in normal rats. The progression of the nephropathy in the SDT rats was considered to be related to increased internal uric acid and blood glucose levels due to the high fructose intake. In conclusion, high fructose intake exaggerated the renal lesions in the SDT rats probably due to effects on the tubules and interstitium through metabolic implications for uric acid and glucose.

Oxidative Stress as a Mechanism Involved in Kidney Damage After Subchronic Exposure to Vanadium Inhalation and Oral Sweetened Beverages in a Mouse Model

Kidney diseases have notably increased in the last few years. This is partially explained by the increase in metabolic syndrome, diabetes, and systemic blood hypertension. However, there is a segment of the population that has neither of the previous risk factors, yet suffers kidney damage. Exposure to atmospheric pollutants has been suggested as a possible risk factor. Air-suspended particles carry on their surface a variety of fuel combustion-related residues such as metals, and vanadium is one of these. Vanadium might produce oxidative stress resulting in the damage of some organs such as the kidney. Additionally, in countries like Mexico, the ingestion of sweetened beverages is a major issue; whether these beverages alone are responsible for direct kidney damage or whether their ingestion promotes the progression of an existing renal damage generates controversy. In this study, we report the combined effect of vanadium inhalation and sweetened beverages ingestion in a mouse model. Forty CD-1 male mice were distributed in 4 groups: control, vanadium inhalation, 30% sucrose in drinking water, and vanadium inhalation plus sucrose 30% in drinking water. Our results support that vanadium inhalation and the ingestion of 30% sucrose induce functional and histological kidney damage and an increase in oxidative stress biomarkers, which were higher in the combined effect of vanadium plus 30% sucrose. The results also support that the ingestion of 30% sucrose alone without hyperglycemia also produces kidney damage.

Consumption of caffeinated beverages and serum concentrations of sex steroid hormones in US men

BACKGROUND

By modulating the levels of sex steroid hormones and sex hormone-binding globulin (SHBG), caffeine could be a factor in the development of several conditions in men, including prostate cancer. The aim of this study was to evaluate if caffeine consumption is associated with concentrations of sex steroid hormones and SHBG in men.

METHODS

1,410 men aged 20 + years who attended the morning examination session of the Third National Health and Nutrition Examination Survey (1988-1991) were included in the analysis. Coffee and soft drink consumption was assessed using a food frequency questionnaire. Daily caffeine intake was estimated by multiplying caffeine content per cup times the daily frequency of coffee, tea, or soft drink consumption. Serum levels of hormones and SHBG were measured by immunoassay. Associations of frequency of beverage consumption or estimated caffeine intake with hormone levels were examined using multivariable linear regression.

RESULTS

Coffee consumption was positively associated with SHBG concentration (p = 0.045) taking lifestyle factors into account, but mutually adjusting for testosterone and estradiol attenuated the association; no association with SHBG was observed for soft drink consumption or caffeine intake. No associations between caffeinated beverage consumption and androgen or estrogen concentrations were observed.

CONCLUSION

Men who drink coffee more frequently may have higher circulating SHBG concentration, but there were no consistent associations for soft drinks or caffeine intake.

Health outcomes of non-nutritive sweeteners: analysis of the research landscape

BACKGROUND

Food products containing non-nutritive sweeteners (NNSs) instead of sugar have become increasingly popular in the last decades. Their appeal is obviously related to their calorie-free sweet taste. However, with the dramatic increase in their consumption, it is reasonable and timely to evaluate their potential health benefits and, more importantly, potential adverse effects. The main aim of this scoping review was to map the evidence about health outcomes possibly associated with regular NNS consumption by examining the extent, range, and nature of research activity in this area.

METHODS

We systematically searched Ovid MEDLINE, EMBASE and the Cochrane CENTRAL databases for studies on NNSs (artificial sweeteners or natural, non-caloric sweeteners, either used individually or in combination) using text terms with appropriate truncation and relevant indexing terms. All human studies investigating any health outcomes of a NNS intervention or exposure were eligible for inclusion. No studies were excluded based on language, study design or methodological quality. Data for each health outcome were summarized in tabular form and were discussed narratively.

RESULTS

Finally, we included 372 studies in our scoping review, comprising 15 systematic reviews, 155 randomized controlled trials (RCTs), 23 non-randomized controlled trials, 57 cohort studies, 52 case-control studies, 28 cross sectional studies and 42 case series/case reports. In healthy subjects, appetite and short term food intake, risk of cancer, risk of diabetes, risk of dental caries, weight gain and risk of obesity are the most investigated health outcomes. Overall there is no conclusive evidence for beneficial and harmful effects on those outcomes. Numerous health outcomes including headaches, depression, behavioral and cognitive effects, neurological effects, risk of preterm delivery, cardiovascular effects or risk of chronic kidney disease were investigated in fewer studies and further research is needed. In subjects with diabetes and hypertension, the evidence regarding health outcomes of NNS use is also inconsistent.

CONCLUSIONS

This scoping review identifies the needs for future research to address the numerous evidence gaps related to health effects of NNSs use.It also specifies the research questions and areas where a systematic review with meta-analyses is required for the proper evaluation of health outcomes associated to regular NNSs consumption.

The Chronic Kidney Disease Water Intake Trial: Protocol of a Randomized Controlled Trial

Background:

In observational studies, drinking more water associates with a slower rate of kidney function decline; whether the same is true in a randomized controlled trial is unknown.

Objective:

To examine the 1-year effect of a higher vs usual water intake on estimated glomerular filtration rate (eGFR) in patients with chronic kidney disease.

Design:

Parallel-group randomized controlled trial.

Setting:

Nine centers in Ontario, Canada. Enrollment and randomization occurred between May 2013 and May 2016; follow-up for the primary outcome will continue until June 2017.

Participants:

Adults (n = 631) with stage 3 chronic kidney disease (eGFR 30-60 mL/min/1.73 m²) and microalbuminuria.

Intervention:

The high water intake group was coached to increase their oral water intake by 1.0 to 1.5 L/day (depending on sex and weight), over and above usual consumed beverages, for a period of 1 year. The control group was coached to maintain their usual water intake during this time.

Measures:

Participants provided 24-hour urine samples at baseline and at 6 and 12 months after randomization; urine samples were analyzed for volume, creatinine, osmolality, and the albumin-to-creatinine ratio. Blood samples were obtained at baseline and at 3- to 6-month intervals after randomization, and analyzed for creatinine, copeptin, osmolality, and electrolytes. Other measures collected included health-related quality of life, blood pressure, body mass index, and diet.

Primary outcome:

The between-group change in eGFR from baseline (prerandomization) to 12 months after randomization.

Secondary outcomes:

Change in plasma copeptin concentration, 24-hour urine albumin-to-creatinine ratio, measured creatinine clearance, estimated 5-year risk of kidney failure (using the 4-variable Kidney Failure Risk Equation), and health-related quality of life.

Planned analysis:

The primary analysis will follow an intention-to-treat approach. The between-group change in eGFR will be compared using linear regression. Supplementary analyses will examine alternative definitions of eGFR change, including annual percentage change, rate of decline, and rapid decline (a P value <0.05 will be interpreted as statistically significant if there is concordance with the primary outcome).

Trial Registration:

This randomized controlled trial has been registered at www.clinicaltrials.gov; government identifier: NCT01766687.

The Effect of Diet on the Survival of Patients with Chronic Kidney Disease

The prevalence of chronic kidney disease (CKD) is high and it is gradually increasing. Individuals with CKD should introduce appropriate measures to hamper the progression of kidney function deterioration as well as prevent the development or progression of CKD-related diseases. A kidney-friendly diet may help to protect kidneys from further damage. Patients with kidney damage should limit the intake of certain foods to reduce the accumulation of unexcreted metabolic products and also to protect against hypertension, proteinuria and other heart and bone health problems. Despite the fact that the influence of certain types of nutrients has been widely studied in relation to kidney function and overall health in CKD patients, there are few studies on the impact of a specific diet on their survival. Animal studies demonstrated prolonged survival of rats with CKD fed with protein-restricted diets. In humans, the results of studies are conflicting. Some of them indicate slowing down of the progression of kidney disease and reduction in proteinuria, but other underline significant worsening of patients' nutritional state, which can be dangerous. A recent systemic study revealed that a healthy diet comprising many fruits and vegetables, fish, legumes, whole grains, and fibers and also the cutting down on red meat, sodium, and refined sugar intake was associated with lower mortality in people with kidney disease. The aim of this paper is to review the results of studies concerning the impact of diet on the survival of CKD patients.

Stirring the Pot: Can Dietary Modification Alleviate the Burden of CKD?

Diet is one of the largest modifiable risk factors for chronic kidney disease (CKD)-related death and disability. CKD is largely a progressive disease; however, it is increasingly appreciated that hallmarks of chronic kidney disease such as albuminuria can regress over time. The factors driving albuminuria resolution remain elusive. Since albuminuria is a strong risk factor for GFR loss, modifiable lifestyle factors that lead to an improvement in albuminuria would likely reduce the burden of CKD in high-risk individuals, such as patients with diabetes. Dietary therapy such as protein and sodium restriction has historically been used in the management of CKD. Evidence is emerging to indicate that other nutrients may influence kidney health, either through metabolic or haemodynamic pathways or via the modification of gut homeostasis. This review focuses on the role of diet in the pathogenesis and progression of CKD and discusses the latest findings related to the mechanisms of diet-induced kidney disease. It is possible that optimizing diet quality or restricting dietary intake could be harnessed as an adjunct therapy for CKD prevention or progression in susceptible individuals, thereby reducing the burden of CKD.

Diet Soda Consumption and Risk of Incident End Stage Renal Disease

BACKGROUND AND OBJECTIVES

Diet soda consumption is common in the United States and is associated with impaired glucose metabolism, diabetes, and metabolic syndrome.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We prospectively analyzed diet soda consumption, assessed by food frequency questionnaire at baseline (1987-1989) and a follow-up examination (1993-1995), and incident ESRD through December 31, 2012 in the Atherosclerosis Risk in Communities study (n=15,368).

RESULTS

Baseline mean age of participants was 54 years, 55% were female, and 27% were black. The majority of participants (43.5%) consumed <1 glass/wk of diet soda; 17.8% consumed 1-4 glasses/wk; 25.3% consumed 5-7 glasses/wk; and 13.5% consumed >7 glasses/wk. Over a median follow-up of 23 years, 357 incident ESRD cases were observed. Relative to <1 glass/wk of diet soda, consuming 1-4 glasses/wk, 5-7 glasses/wk, and >7 glasses/wk, respectively, was associated with 1.08-times (95% confidence interval [95% CI], 0.75 to 1.55), 1.33-times (95% CI, 1.01 to 1.75), and 1.83-times (95% CI, 1.01 to 2.52) higher risk of ESRD after adjusting for age, sex, race-center, education level, smoking status, physical activity, total caloric intake, eGFR, body mass index category, diabetes, systolic BP, and serum uric acid (P value for trend <0.001). Results were similar after additional adjustment for dietary acid load, diet quality, dietary sodium, dietary fructose, sugar-sweetened beverages, and dietary phosphorus. Risk estimates were similar by body mass index category (P value for interaction = 0.82), but the association between diet soda and ESRD was only significant for those who were overweight or obese at baseline. Sugar-sweetened beverage consumption was not significantly associated with ESRD in the fully adjusted model.

CONCLUSIONS

Diet soda consumption was associated with higher ESRD risk in this general population sample. Further research is necessary to validate these findings in other study populations and to examine potential mechanisms through which diet soda could impact kidney disease.

Heat stress, hydration and uric acid: a cross-sectional study in workers of three occupations in a hotspot of Mesoamerican nephropathy in Nicaragua

OBJECTIVES

To study Mesoamerican nephropathy (MeN) and its risk factors in three hot occupations.

DESIGN

Cross-sectional.

SETTING

Chinandega and León municipalities, a MeN hotspot on the Nicaraguan Pacific coast, January-February 2013.

PARTICIPANTS

194 male workers aged 17-39 years: 86 sugarcane cutters, 56 construction workers, 52 small-scale farmers.

OUTCOME MEASURES

(1) Differences between the three occupational groups in prevalences/levels of socioeconomic, occupational, lifestyle and health risk factors for chronic kidney disease (CKD) and in biomarkers of kidney function and hydration; (2) differences in prevalences/levels of CKD risk factors between workers with reduced estimated glomerular filtration rate (eGFR_CKD-EPI <80 mL/min/1.73 m²) and workers with normal kidney function (eGFR_CKD-EPI ≥80 mL/min/1.73 m²).

RESULTS

Sugarcane cutters were more exposed to heat and consumed more fluid on workdays and had less obesity, lower blood sugar, lower blood pressure and a better lipid profile. Reduced eGFR occurred in 16%, 9% and 2% of sugarcane cutters, construction workers and farmers, respectively (trend cane > construction > farming, p=0.003). Significant trends (cane > construction > farming) were also observed for high serum urea nitrogen (blood urea nitrogen (BUN) >20 mg/dL), high serum creatinine (SCr >1.2 mg/dL), low urinary pH (≤5.5) and high BUN/SCr ratio (>20) but not for high urinary specific gravity (≥1.030). Sugarcane cutters also more often had proteinuria and blood and leucocytes in the urine. Workers with eGFR <80 mL/min/1.73 m² reported a higher intake of water and lower intake of sugary beverages. Serum uric acid levels related strongly and inversely to eGFR levels (adj β -10.4 mL/min/1.73 m², 95% CI -12.2 to -8.5, p<0.001). No associations were observed for other metabolic risk factors, pesticides, non-steroidal anti-inflammatory drugs or alcohol. Among cane cutters, consumption of electrolyte hydration solution appeared preventive (adj β 8.1 mL/min/1.73 m², p=0.09).

CONCLUSIONS

Heat stress, dehydration and kidney dysfunction were most common among sugarcane cutters. Kidney dysfunction also occurred to a lesser extent among construction workers, but hardly at all among small-scale farmers. High serum uric acid was associated with reduced kidney function.

Nuciferine Alleviates Renal Injury by Inhibiting Inflammatory Responses in Fructose-Fed Rats

Nuciferine is a major active component from the lotus leaf. This study examines the effects of nuciferine on fructose-induced renal injury and explores its possible mechanism. Rats consumed drinking water or 10% fructose for 12 weeks. Fructose-fed rats were orally treated with water or 7, 14, or 28 mg/kg of nuciferine for the last 6 weeks. HK-2 cells were exposed to 5 mM fructose alone or in combination with nuciferine (2.5-40 μM) for 24 h. Nuciferine significantly attenuated fructose-induced hyperuricemia, dyslipidemia, and systemic inflammation in rats. More importantly, it alleviated renal pathological injury with proteinuria at 20 and 40 mg/kg (2.58 ± 0.97 and 2.48 ± 1.04 mg/mg·creatinine, P < 0.05) compared with fructose-vehicle group (4.10 ± 1.18 mg/mg·creatinine). Furthermore, nuciferine reduced TLR4, MyD88, PI3K, ILK, p-AKT, p-P65, and NLRP3 inflammasome protein levels (P < 0.05 for all) in the renal cortex of fructose-fed rats (14 and 28 mg/kg) and fructose-exposed HK-2 cells (5-40 μM), which is consistent with its reduction of inflammatory cytokines IL-1β, IL-6, TNF-α, and MCP-1 (P < 0.05 for all) in vivo and in vitro. These findings suggest that nuciferine alleviated fructose-induced inflammation by inhibiting TLR4/PI3K/NF-κB signaling and NLRP3 inflammasome activation in rat renal cortex and HK-2 cells, which may contribute to the improvement of renal injury.

Aging-associated renal disease in mice is fructokinase dependent

Aging-associated kidney disease is usually considered a degenerative process associated with aging. Recently, it has been shown that animals can produce fructose endogenously, and that this can be a mechanism for causing kidney damage in diabetic nephropathy and in association with recurrent dehydration. We therefore hypothesized that low-level metabolism of endogenous fructose might play a role in aging-associated kidney disease. Wild-type and fructokinase knockout mice were fed a normal diet for 2 yr that had minimal (<5%) fructose content. At the end of 2 yr, wild-type mice showed elevations in systolic blood pressure, mild albuminuria, and glomerular changes with mesangial matrix expansion, variable mesangiolysis, and segmental thrombi. The renal injury was amplified by provision of high-salt diet for 3 wk, as noted by the presence of glomerular hypertrophy, mesangial matrix expansion, and alpha smooth muscle actin expression, and with segmental thrombi. Fructokinase knockout mice were protected from renal injury both at baseline and after high salt intake (3 wk) compared with wild-type mice. This was associated with higher levels of active (phosphorylated serine 1177) endothelial nitric oxide synthase in their kidneys. These studies suggest that aging-associated renal disease might be due to activation of specific metabolic pathways that could theoretically be targeted therapeutically, and raise the hypothesis that aging-associated renal injury may represent a disease process as opposed to normal age-related degeneration.

Added sugars drive chronic kidney disease and its consequences: A comprehensive review

The consumption of added sugars (e.g. sucrose [table sugar] and high-fructose corn syrup) over the last 200 years has increased exponentially and parallels the increased prevalence of chronic kidney disease (CKD). Data for animals and humans suggest that the consumption of added sugars leads to kidney damage and related metabolic derangements that increase cardiovascular risk. Importantly, the consumption of added sugars has been found to induce insulin resistance and increase uric acid in humans, both of which increase the conversion of glucose to fructose (i.e. fructogenesis) via the polyol pathway. The polyol pathway has recently been implicated in the contribution and progression of kidney damage, suggesting that even glucose can be toxic to the kidney via its endogenous transformation into fructose in the proximal tubule. Consuming added fructose has been shown to induce insulin resistance, which can lead to hyperglycaemia, oxidative stress, inflammation and the activation of the immune system, all of which can synergistically contribute to kidney damage. CKD guidelines should stress a reduction in the consumption of added sugars as a means to prevent and treat CKD as well as reduce CKD–related morbidity and mortality.

Rehydration with soft drink-like beverages exacerbates dehydration and worsens dehydration-associated renal injury

Recurrent dehydration, such as commonly occurs with manual labor in tropical environments, has been recently shown to result in chronic kidney injury, likely through the effects of hyperosmolarity to activate both vasopressin and aldose reductase-fructokinase pathways. The observation that the latter pathway can be directly engaged by simple sugars (glucose and fructose) leads to the hypothesis that soft drinks (which contain these sugars) might worsen rather than benefit dehydration associated kidney disease. Recurrent dehydration was induced in rats by exposure to heat (36°C) for 1 h/24 h followed by access for 2 h to plain water (W), a 11% fructose-glucose solution (FG, same composition as typical soft drinks), or water sweetened with noncaloric stevia (ST). After 4 wk plasma and urine samples were collected, and kidneys were examined for oxidative stress, inflammation, and injury. Recurrent heat-induced dehydration with ad libitum water repletion resulted in plasma and urinary hyperosmolarity with stimulation of the vasopressin (copeptin) levels and resulted in mild tubular injury and renal oxidative stress. Rehydration with 11% FG solution, despite larger total fluid intake, resulted in greater dehydration (higher osmolarity and copeptin levels) and worse renal injury, with activation of aldose reductase and fructokinase, whereas rehydration with stevia water had opposite effects. In animals that are dehydrated, rehydration acutely with soft drinks worsens dehydration and exacerbates dehydration associated renal damage. These studies emphasize the danger of drinking soft drink-like beverages as an attempt to rehydrate following dehydration.

Effects of acute and chronic hypohydration on kidney health and function

The kidneys play a critical role in the homeostasis of body fluid tonicity and effective circulating volume. Renal homeostatic mechanisms are frequently challenged in acutely ill people. Fluid depletion causing hypovolemia may result in renal hypoperfusion that, if left untreated, may lead to acute kidney failure. Some populations, notably older people and neonates, are less tolerant of extremes in fluid loading and deprivation, similar to those with established chronic kidney disease. Risk of kidney injury during fluid depletion is increased by medications including diuretics, nonsteroidal antiinflammatory drugs, and renin-angiotensin system blockers. There is no consistent evidence indicating that lower-than-average fluid intake can cause chronic kidney disease, nor accelerate progression of established kidney disease. Increasing consumption of sugar-containing beverages is, however, a major concern for kidney health as a precursor of obesity and diabetes. There is no evidence that high dietary protein intake can cause chronic kidney disease, nor accelerate progression of established kidney disease. Idiosyncratic, adverse renal responses have been described with creatine supplements. There are only a few clinical conditions for which high fluid intake should be considered. These include recurrent kidney stones or urinary tract infections and, possibly, polycystic kidney disease.

Fructose and Cardiometabolic Health: What the Evidence From Sugar-Sweetened Beverages Tells Us

Recent attention has focused on fructose as having a unique role in the pathogenesis of cardiometabolic diseases. However, because we rarely consume fructose in isolation, the major source of fructose in the diet comes from fructose-containing sugars, sucrose and high fructose corn syrup, in sugar-sweetened beverages and foods. Intake of sugar-sweetened beverages has been consistently linked to increased risk of obesity, type 2 diabetes, and cardiovascular disease in various populations. Putative underlying mechanisms include incomplete compensation for liquid calories, adverse glycemic effects, and increased hepatic metabolism of fructose leading to de novo lipogenesis, production of uric acid, and accumulation of visceral and ectopic fat. In this review we summarize the epidemiological and clinical trial evidence evaluating added sugars, especially sugar-sweetened beverages, and the risk of obesity, diabetes, and cardiovascular disease and address potential biological mechanisms with an emphasis on fructose physiology. We also discuss strategies to reduce intake of fructose-containing beverages.

Dietary (-)-epicatechin mitigates oxidative stress, NO metabolism alterations, and inflammation in renal cortex from fructose-fed rats

High fructose consumption has been associated to deleterious metabolic conditions. In the kidney, high fructose causes renal alterations that contribute to the development of chronic kidney disease. Evidence suggests that dietary flavonoids have the ability to prevent/attenuate risk factors of chronic diseases. This work investigated the capacity of (-)-epicatechin to prevent the renal damage induced by high fructose consumption in rats. Male Sprague Dawley rats received 10% (w/v) fructose in the drinking water for 8 weeks, with or without supplementation with (-)-epicatechin (20mg/kg body weight/d) in the rat chow diet. Results showed that, in the presence of mild proteinuria, the renal cortex from fructose-fed rats exhibited fibrosis and decreases in nephrin, synaptopodin, and WT1, all indicators of podocyte function in association with: (i) increased markers of oxidative stress; (ii) modifications in the determinants of NO bioavailability, i.e., NO synthase (NOS) activity and expression; and (iii) development of a pro-inflammatory condition, manifested as NF-κB activation, and associated with high expression of TNFα, iNOS, and IL-6. Dietary supplementation with (-)-epicatechin prevented or ameliorated the adverse effects of high fructose consumption. These results suggest that (-)-epicatechin ingestion would benefit when renal alterations occur associated with inflammation or metabolic diseases.

Dashing away hypertension: Evaluating the efficacy of the dietary approaches to stop hypertension diet in controlling high blood pressure

The dietary approaches to stop hypertension (DASH) diet has been developed and popularized as a non-pharmaceutical intervention for high blood pressure reduction since 1995. However, to date, a comprehensive description of the biochemical rationale behind the diet’s principal guidelines has yet to be compiled. With rising interest for healthy and reliable life-style modifications to combat cardiovascular disease, this review aims to compile the most recent and relevant studies on this topic and make an informed assessment as to the efficacy of and underlying mechanisms operant in the DASH diet. Specifically, the merits of lowering dietary intake of sodium and saturated fat, as well as increasing the intake of fruits, vegetables, fiber, and dairy, have been shown to attenuate hypertension individually. Upon review of this evidence, we conclude that the combination of dietary patterns proposed in the DASH diet is effective in attenuating high blood pressure. We also suggest that efforts to more widely implement adoption of the DASH diet would be beneficial to public health.

Associations of sugar-sweetened and artificially sweetened soda with chronic kidney disease: a systematic review and meta-analysis

BACKGROUND/OBJECTIVES

The risk of chronic kidney disease (CKD) in patients who regularly drink soda is controversial. The objective of this meta-analysis was to evaluate the associations between consumption of sugar-sweetened and artificially sweetened soda and CKD.

METHODS

A literature search was performed using MEDLINE, EMBASE and the Cochrane Database of Systematic Reviews from inception until 30 June 2014. Studies that reported odds ratios or hazard ratios comparing the risk of CKD in patients consuming significant amounts of either sugar-sweetened or artificially sweetened soda versus those who did not consume soda were included. Pooled risk ratios (RR) and 95% confidence intervals (CI) were calculated using a random-effects, generic inverse variance method.

RESULTS

Five studies were included in our analysis of the association between consumption of sugar-sweetened soda and CKD. The pooled RR of CKD in patients consuming sugar-sweetened soda was 1.58 (95% CI 1.00-2.49). Four studies were selected to assess the association between consumption of artificially sweetened soda and CKD. The pooled RR of CKD in patients consuming artificially sweetened soda was 1.33 (95% CI 0.82-2.15).

CONCLUSIONS

Our study demonstrates statistically significant increased risks of CKD in patients consuming sugar-sweetened soda, but not in patients consuming artificially sweetened soda. This finding suggests that sugar-sweetened soda consumption is associated with CKD and may impact clinical management and primary prevention of CKD in high-risk patients.

Mechanisms by Which Dehydration May Lead to Chronic Kidney Disease

Dehydration, a condition that characterizes excessive loss of body water, is well known to be associated with acute renal dysfunction; however, it has largely been considered reversible and to be associated with no long-term effects on the kidney. Recently, an epidemic of chronic kidney disease has emerged in Central America in which the major risk factor seems to be recurrent heat-associated dehydration. This has led to studies investigating whether recurrent dehydration may lead to permanent kidney damage. Three major potential mechanisms have been identified, including the effects of vasopressin on the kidney, the activation of the aldose reductase-fructokinase pathway, and the effects of chronic hyperuricemia. The discovery of these pathways has also led to the recognition that mild dehydration may be a risk factor in progression of all types of chronic kidney diseases. Furthermore, there is some evidence that increasing hydration, particularly with water, may actually prevent CKD. Thus, a whole new area of investigation is developing that focuses on the role of water and osmolarity and their influence on kidney function and health.

Diabetes and Kidney Disease in American Indians: Potential Role of Sugar-Sweetened Beverages

Since the early 20th century, a marked increase in obesity, diabetes, and chronic kidney disease has occurred in the American Indian population, especially the Pima Indians of the Southwest. Here, we review the current epidemic and attempt to identify remediable causes. A search was performed using PubMed and the search terms American Indian and obesity, American Indian and diabetes, American Indian and chronic kidney disease, and American Indian and sugar or fructose, Native American, Alaska Native, First Nations, Aboriginal, Amerind, and Amerindian for American Indian for articles linking American Indians with diabetes, obesity, chronic kidney disease, and sugar; additional references were identified in these publications traced to 1900 and articles were reviewed if they were directly discussing these topics. Multiple factors are involved in the increased risk for diabetes and kidney disease in the American Indian population, including poverty, overnutrition, poor health care, high intake of sugar, and genetic mechanisms. Genetic factors may be especially important in the Pima, as historical records suggest that this group was predisposed to obesity before exposure to Western culture and diet. Exposure to sugar-sweetened beverages may also be involved in the increased risk for chronic kidney disease. In these small populations in severe health crisis, we recommend further studies to investigate the role of excess added sugar, especially sugar-sweetened beverages, as a potentially remediable risk factor.

Socioeconomic disparities in chronic kidney disease: a systematic review and meta-analysis

CONTEXT

Evidence on the strength of the association between low SES and chronic kidney disease (CKD; measured by low estimated glomerular filtration rate [eGFR], high albuminuria, low eGFR/high albuminuria, and renal failure) is scattered and sometimes conflicting. Therefore, a systematic review and meta-analysis was performed to summarize the strength of the associations between SES and CKD and identify study-level characteristics related to this association.

EVIDENCE ACQUISITION

Studies published through January 2013 in MEDLINE and Embase were searched. From 35 studies that met the inclusion criteria, association estimates were pooled per CKD measure in the meta-analysis (performed between 2013 and 2014). Meta-regression analysis was used to identify study-level characteristics related to the strength of the SES-CKD association.

EVIDENCE SYNTHESIS

Low SES was associated with low eGFR (OR=1.41, 95% CI=1.21, 1.62), high albuminuria (OR=1.52, 95% CI=1.22, 1.82), low eGFR/high albuminuria (OR=1.38, 95% CI=1.03, 1.74), and renal failure (OR=1.55, 95% CI=1.40, 1.71). Differences in SES measures across studies were not related to the strength of associations between low SES and any of the CKD measures (low GFR, p=0.63; high albuminuria, p=0.29; low eGFR/high albuminuria, p=0.54; renal failure, p=0.31). Variations in the strength of associations were related to the level of covariate adjustment for low eGFR (p<0.001) and high albuminuria (p<0.001).

CONCLUSIONS

Socioeconomic disparities in CKD were fairly strong, irrespective of how SES was measured. Variations in the strength of the associations were related to the level of covariate adjustment, particularly for low eGFR and high albuminuria.

Hispanic Americans living in the United States and their risk for obesity, diabetes and kidney disease: Genetic and environmental considerations

The Hispanic American, the largest minority population in the United States, is at increased risk for obesity, diabetes and end-stage renal disease. Here we review genetic and environmental factors that might account for their increased risk for these conditions. Whereas many environmental and genetic factors have important roles in driving the increased risk for obesity and kidney disease in this population, a case is made that excessive intake of sugary beverages is a contributory cause. Studies focusing on decreasing intake of sugary beverages among the Hispanic American could potentially reduce renal and cardiovascular complications in this population.