A low-carbohydrate diet may prevent end-stage renal failure in type 2 diabetes. A case report

Comparative Efficacy of Low-Carbohydrate and Ketogenic Diets on Diabetic Retinopathy and Oxidative Stress in High-Fat Diet-Induced Diabetic Rats

This study examined the effect of a low-carbohydrate diet (LCD) and a low-carbohydrate ketogenic diet (LCKD) on diabetic retinopathy in high-fat diet-induced diabetes mellitus in rats and studied the mechanisms of action. Rats were divided into four groups: the Control group, which was fed a normal diet for 16 weeks; the HFD group, which was fed a high-fat diet (HFD) for the first 8 weeks and then switched to a normal diet for 8 weeks; the HFD+LCD group, fed a HFD for 8 weeks followed by an LCD for 8 weeks, and the HFD+LCKD group, which was fed a HFD for 8 weeks followed by an LCKD for 8 more weeks. Both the LCD and the LCKD effectively reduced the final body and total fat weights and decreased fasting serum levels of glucose, insulin, hemoglobin A1 (HbA1C), triglycerides, cholesterol, and LDL-c. They also reduced the levels of malondialdehyde (MDA), tumor necrosis factor-α, vascular endothelial factor, caspapse-3, and bax. In the HFD rats, we found increased serum levels of β-Hydroxybutyrate and upregulated expression of Bcl2, glutathione, superoxide dismutase, and hemeoxygenase-1. Moreover, the LCD and LCKD significantly reduced mRNA levels of Kelch-like ECH-associated protein 1 (Keap1) and enhanced mRNA and nuclear concentrations of nuclear factor erythroid factor 2 (Nrf2). All these effects were associated with improved layers of the retina in the HFD - LCD and HFD + LCKD rats but not in HFD animals. The impact of the LCKD was always more profound on all measured parameters and on improving the structure of the retina compared to the LCD. In conclusion, the LCKD is superior to the LCD in preventing diabetic retinopathy in HFD-fed rats. Mechanistically, our results suggest that the hypoglycemic and hypolipidemic conditions and the Nrf2-dependent antioxidant and anti-inflammatory effects may be involved in the preventative effects of the LCD and LCKD.

Chronic Kidney Disease Interplay with Comorbidities and Carbohydrate Metabolism: A Review

Chronic kidney disease (CKD) poses a global health challenge, engendering various physiological and metabolic shifts that significantly impact health and escalate the susceptibility to severe illnesses. This comprehensive review delves into the intricate complexities of CKD, scrutinizing its influence on cellular growth homeostasis, hormonal equilibrium, wasting, malnutrition, and its interconnectedness with inflammation, oxidative stress, and cardiovascular diseases. Exploring the genetic, birth-related, and comorbidity factors associated with CKD, alongside considerations of metabolic disturbances, anemia, and malnutrition, the review elucidates how CKD orchestrates cellular growth control. A pivotal focus lies on the nexus between CKD and insulin resistance, where debates persist regarding its chronological relationship with impaired kidney function. The prevalence of insulin abnormalities in CKD is emphasized, contributing to glucose intolerance and raising questions about its role as a precursor or consequence. Moreover, the review sheds light on disruptions in the growth hormone and insulin-like growth factor axis in CKD, underscoring the heightened vulnerability to illness and mortality in cases of severe growth retardation. Wasting, a prevalent concern affecting up to 75% of end-stage renal disease (ESRD) patients, is analyzed, elucidating the manifestations of cachexia and its impact on appetite, energy expenditure, and protein reserves. Taste disturbances in CKD, affecting sour, umami, and salty tastes, are explored for their implications on food palatability and nutritional status. Independent of age and gender, these taste alterations have the potential to sway dietary choices, further complicating the management of CKD. The intricate interplay between CKD, inflammation, oxidative stress, and cardiovascular diseases is unraveled, emphasizing the profound repercussions on overall health. Additionally, the review extends its analysis to CKD's broader impact on cognitive function, emotional well-being, taste perception, and endothelial dysfunction. Concluding with an emphasis on dietary interventions as crucial components in CKD management, this comprehensive review navigates the multifaceted dimensions of CKD, providing a nuanced understanding essential for developing targeted therapeutic strategies.

Low-Carbohydrate and Very-Low-Carbohydrate Diets in Patients With Diabetes

Low-carbohydrate diets have been advocated as an effective method for promoting weight loss in overweight and obese individuals and preventing and treating type 2 diabetes. This article reviews the differences between various low-carbohydrate eating plans and discusses the benefits and drawbacks of such a diet based on available evidence. It also offers practical pointers for clinicians.

An evidence-based approach to developing low-carbohydrate diets for type 2 diabetes management: A systematic review of interventions and methods

AIM

To identify core diet and delivery components of low-carbohydrate (CHO) diets that have demonstrated efficacy for type 2 diabetes (T2D) management.

MATERIALS AND METHODS

MEDLINE, Pre-MEDLINE, EMBASE, CINAHL and the Cochrane Library of Controlled Trials databases were systematically searched from inception until August 18, 2018. Primary intervention studies of low-CHO diets (≤130 g/d or 26% total energy intake [TEI]) were included. Content analysis was performed on the low-CHO diet protocols classified as safe and effective for T2D management.

RESULTS

A total of 41 studies published between 1963 and 2018 were included, of which 40 were classified as safe and effective for inclusion in the primary analysis. Thirteen studies (13/40) were on very-low-CHO diets (<50 g/d), 14/40 included low-CHO diets (≤130 g/d or 26% TEI), and 13/40 were adapted according to participant progress. Thirty-one studies reported a total energy prescription, of which 18/31 encouraged ad libitum intakes. Twenty studies reported a prescribed dietary fat amount, of which 18/20 were unrestricted or high-fat (>35% TEI). Twenty-six studies reported a prescribed dietary protein amount, of which 22 were unrestricted or were high-protein (>25% TEI). The types of dietary CHO, fat and protein recommended were predominantly whole foods. Common delivery methods reported were dietician and/or physician involvement, moderate to high frequency of contact (≥1 session/month) and use of participant self-monitoring.

CONCLUSIONS

Multiple approaches for developing and delivering a low-CHO diet intervention for T2D management are safe and effective. A comprehensive set of core dietary components to consider in the formulation of low-CHO diet protocols were identified for use in clinical practice and to inform evidence-based guidelines for T2D management.

Dietary restriction regimens for fighting kidney disease: Insights from rodent studies

This review critically discusses the research findings on the effects of various dietary restriction regimens in rodent models of kidney disease. Long-term caloric restriction executed at both early and progressive stages of kidney disease was found to exert beneficial effects in rodents. Moreover, some studies have also demonstrated the efficacy of short-term caloric restriction in treating the kidney disease of variable aetiologies possibly by improving mitochondrial dysfunction, autophagy process and suppression of inflammation. However, the mechanisms underlying these short-term caloric restriction mediated protective effects in rodent models of kidney disease are not completely understood. Importantly, few available evidences have also suggested that carbohydrate restriction can exert beneficial effects in aging and experimentally induced renal injury models, but the mechanisms are not explored yet. Interestingly, the benefits of low protein diet in kidney disease models are extensively reported in literature. However, in most of these studies implementation of the low protein dietary regimen was found to associated with increased high carbohydrate and caloric intake (non-isocaloric). Thus, testing the effects of low protein diet under isocaloric conditions might further help to particularly understand the role of dietary protein content in pathology of kidney disease. Moreover, the direct evidences comparing the efficacy of various dietary restriction regimens in rodent models of kidney diseases are also scarce at present.

Dietary intake in type 1 diabetes at different stages of diabetic kidney disease

AIM

Diet plays an important role in the kidney health of individuals with type 1 diabetes. However, not much is known about dietary practices at different stages of diabetic nephropathy. We aimed at investigating food intake, dietary patterns, and nutrient intakes in individuals with type 1 diabetes differing in renal status.

METHODS

Data were available from 1874 individuals with type 1 diabetes (45% men, age 48 ± 13 years). Diet was assessed at the levels of food items and diet patterns (diet questionnaire), and energy and nutrient intakes (food record). Six groups were formed based on the eGFR or dialysis and transplantation status.

RESULTS

Reductions in liquid-milk product and salt consumption, and increase in special diet adherence were observed at the early stages of eGFR decline. Reduced coffee consumption was observed after eGFR was <30 ml/min/1.73 m². With advancing kidney failure, rye bread consumption decreased, but that of wheat bread increased. Compared to those with intact kidney function (the index group), the Fish and vegetable diet pattern scores were higher in individuals with mildly-to-severely decreased eGFR. Instead, the Sweet pattern scores were lower than in the index group in all other groups. Energy intake was lower in all groups compared to those with intact kidney function. Advancing kidney failure was associated with reductions in protein intake per body weight, and in the intakes of sodium, potassium, calcium, and phosphorus.

CONCLUSIONS

Differences in the dietary intake are seen already at the early stages of kidney function decline.

Gastric Bypass in Chronic Renal Failure and Renal Transplant

BACKGROUND

Morbid obesity has reached epidemic proportions in developed nations worldwide, causing considerable mortality and increased healthcare expenditures. The use of gastric bypass surgery to achieve weight loss in morbidly obese patients with chronic renal failure (CRF) and postrenal transplant patients has not been studied adequately.

METHODS

Forty-one patients with different stages of CRF (25 already receiving dialysis) underwent a gastric bypass (GBP), and an additional 10 patients underwent a GBP after becoming morbidly obese after transplantation.

RESULTS

Of the 41 patients with CRF, 5 stabilized or resolved their kidney disease and 9 underwent successful transplantation. These patients had a loss of 68% excess body mass index (BMI) by 12 months after GBP. Of the 10 patients with GBP after transplant, the mean loss of excess BMI was 70.5%. There were no in-hospital or 30-day mortalities, but 8 of the 51 patients died from 112 to 2869 days postoperatively, 7 from cardiac or vascular events and 1 from an automobile accident. This compares with an approximate 10% mortality per year for patients receiving dialysis. Comorbid conditions associated with morbid obesity improved in all patients and permitted eligibility for transplantation.

CONCLUSIONS

GBP for massive weight reduction in morbidly obese renal failure and transplant patients leads to a reduction in comorbid conditions that are associated with an increased risk for cardiovascular deaths. There was no operative mortality in this series, and all but 1 death were related to previously existing disease of the cardiovascular system.

Dietary cholesterol from eggs increases plasma HDL cholesterol in overweight men consuming a carbohydrate-restricted diet

Carbohydrate-restricted diets (CRD) significantly decrease body weight and independently improve plasma triglycerides (TG) and HDL cholesterol (HDL-C). Increasing intake of dietary cholesterol from eggs in the context of a low-fat diet maintains the LDL cholesterol (LDL-C)/HDL-C for both hyper- and hypo-responders to dietary cholesterol. In this study, 28 overweight/obese male subjects (BMI = 25-37 kg/m2) aged 40-70 y were recruited to evaluate the contribution of dietary cholesterol from eggs in a CRD. Subjects were counseled to consume a CRD (10-15% energy from carbohydrate) and they were randomly allocated to the EGG group [intake of 3 eggs per day (640 mg/d additional dietary cholesterol)] or SUB group [equivalent amount of egg substitute (0 dietary cholesterol) per day]. Energy intake decreased in both groups from 10,243 +/- 4040 to 7968 +/- 2401 kJ (P < 0.05) compared with baseline. All subjects irrespective of their assigned group had reduced body weight and waist circumference (P < 0.0001). Similarly, the plasma TG concentration was reduced from 1.34 +/- 0.66 to 0.83 +/- 0.30 mmol/L after 12 wk (P < 0.001) in all subjects. The plasma LDL-C concentration, as well as the LDL-C:HDL-C ratio, did not change during the intervention. In contrast, plasma HDL-C concentration increased in the EGG group from 1.23 +/- 0.39 to 1.47 +/- 0.38 mmol/L (P < 0.01), whereas HDL-C did not change in the SUB group. Plasma glucose concentrations in fasting subjects did not change. Eighteen subjects were classified as having the metabolic syndrome (MetS) at the beginning of the study, whereas 3 subjects had that classification at the end. These results suggest that including eggs in a CRD results in increased HDL-C while decreasing the risk factors associated with MetS.