High-protein diets in hyperlipidemia: effect of wheat gluten on serum lipids, uric acid, and renal function

Animal vs Plant-Based Meat: A Hearty Debate

Plant-based meat alternatives (PBMAs) are highly processed food products that typically replace meat in the diet. In Canada, the growing demand for PBMAs coincides with public health recommendations to reduce ultra-processed food consumption, which prompts the need to investigate the long-term health implications of PBMAs. This review assesses the available literature on PBMAs and cardiovascular disease (CVD), including an evaluation of their nutritional profile and impact on CVD risk factors. Overall, the nutritional profiles of PBMAs vary considerably but generally align with recommendations for improving cardiovascular health; compared with meat, PBMAs are usually lower in saturated fat and higher in polyunsaturated fat and dietary fibre. Some dietary trials that have replaced meat with PBMAs have reported improvements in CVD risk factors, including total cholesterol, low-density lipoprotein cholesterol, apolipoprotein B-100, and body weight. No currently available evidence suggests that the concerning aspects of PMBAs (eg, food processing and high sodium content) negate the potential cardiovascular benefits. We conclude that replacing meat with PBMAs may be cardioprotective; however, long-term randomised controlled trials and prospective cohort studies that evaluate CVD events (eg, myocardial infarction, stroke) are essential to draw more definitive conclusions.

Dietary protein sources, genetics, and cardiovascular disease incidence

BACKGROUND

To explore the potential correlation between the amount and source of dietary protein and cardiovascular disease (CVD), as well as the potential impact of genetic susceptibility on these connections.

METHODS

We performed a prospective analysis of 98,224 participants from the UK. We measured dietary protein intake using two 24-hour dietary recall interviews. To analyze the data, we used multivariable-adjusted Cox regression models and restricted cubic spline models. Additionally, we calculated weighted genetic risk scores.

RESULTS

A total of 8818 new cases of CVD were documented, which included 4076 cases of coronary artery disease (CAD) and 1126 cases of stroke. The study found a J-shaped association (p nonlinearity = 0.005) between CVD risk and the percentage of energy obtained from consuming plant protein. Higher intake of plant protein and whole protein was associated with a decreased risk of CVD. On the other hand, larger intakes of animal protein was linked to a higher occurrence of CAD. Additionally, increased intake of plant protein was also linked to a lower incidence of stroke. Replacing 5 % of animal protein-based energy intake with plant protein-based energy intake resulted in a 5 % decrease in CVD risk.

LIMITATIONS

There remains an effect of residual confounders.

CONCLUSION

The consumption of larger amounts of plant protein, whole protein, and nut protein was found to be associated with a lower risk of CVD events. Conversely, higher intakes of animal protein was associated with an increased risk of CAD events. Furthermore, replacing 5 % of energy intake from animal protein with energy intake from plant protein was found to reduce the risk of CVD by 5 %.

Protein supplementation: the double-edged sword

Protein supplements are widely consumed by athletes as well as young adults and teenagers going to the gym and are an excellent source to increase protein intake, build muscle mass, and enhance recovery. They are available in the form of powders, gummies, protein bars, and ready-to-drink shakes and have been shown to have effects on almost every system in the body. Subjects consuming whey protein-based supplements regularly show significantly lower systolic blood pressure, while subjects who consume soy-based protein supplements have been reported to show a significant decrease in their systolic and diastolic blood pressures. Favorable effects of soy protein consumption have been observed on the serum lipid profile, with significant decreases in serum low-density lipoprotein and triglyceride levels. Lower postprandial glucose levels have been observed in diabetic subjects as well, which can be attributed to the lower glycemic index of these supplements. This can lead to an indirect decrease in diabetes-related complications. While these supplements affect the body positively, caution has to be exercised while consuming them in excess, as they have been shown to cause hyperfiltration and increased urinary calcium excretion which can, in turn, lead to chronic kidney disease development. This article focuses on the effects of protein supplementation on the human body, with emphasis on the cardiovascular, endocrine, and renal systems.

Decreased cardiovascular risk factors and inflammation with remission of type 2 diabetes in adults with obesity using a high protein diet: Randomized control trial

Objective

The study objective was to determine the effects a high protein (HP) vs. a high carbohydrate (HC) diet on cardiovascular risk factors (CVR), inflammation, metabolic parameters, oxidative stress, weight loss, lean and fat body mass, and remission of Type 2 Diabetes (T2DM) in subjects with obesity.

Research design and methods

Twelve women and men with T2D were recruited and randomized to either a HP (30%protein, 30%fat, 40%carbohydrate) (n = 6) or HC (15%protein, 30%fat, 55%carbohydrate) (n = 6) diet feeding study for 6 months in this randomized controlled trial. All meals were purchased at local grocery stores and provided to subjects for 6 months with daily food menus for HP or HC compliance with weekly food pick-up and weight measurements. Oral glucose tolerance and meal tolerance tests with glucose and insulin measurements and DXA scans were done at baseline and after 6 months on the respective diets.

Results

After 6 months on the HP diet, 100% of the subjects had remission of their T2DM to Normal Glucose Tolerance (NGT), whereas only 16.6% of subjects on the HC diet had remission of their T2DM. The HP diet group exhibited significant improvement in a) cardiovascular risk factors (p = 0.004, b) inflammatory cytokines(p = 0.001), c) insulin sensitivity(p = 0.001), d) oxidative stress(p = 0.001), e) increased %lean body mass(p = 0.001) compared to the HC diet group at 6 months.

Conclusions

A significant improvement in cardiovascular risk factors, inflammation, metabolic parameters and 100% remission of T2DM to NGT was achieved with a HP diet compared to a HC diet at 6 months.

Clinicaltrialsgov identifier

NCT01642849.

Dietary protein score and carbohydrate quality index with the risk of chronic kidney disease: Findings from a prospective cohort study

BACKGROUND/AIM

This study aimed to examine the associations between dietary protein score and carbohydrate quality index (CQI) and the risk of chronic kidney disease (CKD) in Iranian adults.

METHODS

This population-based cohort study was performed within the Tehran Lipid and Glucose Study framework on 6,044 subjects aged ≥18 years old, who were followed up for a mean of 7.7 years. Dietary protein score and CQI were determined using a food frequency questionnaire. CKD was defined as an estimated glomerular filtration rate <60 ml/min/1.73 m2. A multivariate Cox proportional hazard regression model was used to estimate the risk of CKD across tertiles of protein score and CQI.

RESULTS

The mean (standard deviation) of age and body mass index of participants were 37.9 (12.8) years and 26.8 (4.7) kg/m2, respectively. During the 7.7 ± 2.7 years of follow-up, 1,216 cases (20.1%) of CKD were ascertained. In the final adjusted model, individuals in the highest tertile of protein score had decreased risk of CKD (HR: 0.85, 95% CI: 0.74-0.98, P trend = 0.033). Also, there is a significant association between total carbohydrate score (HR: 0.85, 95% CI: 0.73-0.99, P trend = 0.016), the ratio of whole grain/total grains (HR: 0.81, 95% CI: 0.70-0.94, P trend = 0.004), and glycemic index (HR: 1.30, 95% CI: 1.12-1.51, P trend < 0.001) and risk of CKD. However, no significant association was found between total protein intakes, plant-to-animal ratio, and solid carbohydrate/total carbohydrate with the risk of CKD.

CONCLUSION

Our results revealed a diet with a high protein score and high quality of carbohydrates, characterized by higher intakes of plant proteins, low glycaemic index (GI) carbohydrates, whole grain, fibers, and lower intakes of animal proteins, can be related to reduced CKD risk.

How Healthy Are Non-Traditional Dietary Proteins? The Effect of Diverse Protein Foods on Biomarkers of Human Health

Future food security for healthy populations requires the development of safe, sustainably-produced protein foods to complement traditional dietary protein sources. To meet this need, a broad range of non-traditional protein foods are under active investigation. The aim of this review was to evaluate their potential effects on human health and to identify knowledge gaps, potential risks, and research opportunities. Non-traditional protein sources included are algae, cereals/grains, fresh fruit and vegetables, insects, mycoprotein, nuts, oil seeds, and legumes. Human, animal, and in vitro data suggest that non-traditional protein foods have compelling beneficial effects on human health, complementing traditional proteins (meat/poultry, soy, eggs, dairy). Improvements in cardiovascular health, lipid metabolism, muscle synthesis, and glycaemic control were the most frequently reported improvements in health-related endpoints. The mechanisms of benefit may arise from their diverse range of minerals, macro- and micronutrients, dietary fibre, and bioactive factors. Many were also reported to have anti-inflammatory, antihypertensive, and antioxidant activity. Across all protein sources examined, there is a strong need for quality human data from randomized controlled intervention studies. Opportunity lies in further understanding the potential effects of non-traditional proteins on the gut microbiome, immunity, inflammatory conditions, DNA damage, cognition, and cellular ageing. Safety, sustainability, and evidence-based health research will be vital to the development of high-quality complementary protein foods that enhance human health at all life stages.

Nutritional and dietary interventions to prolong renal allograft survival after kidney transplantation

PURPOSE OF REVIEW

Diet plays an important role in slowing progression of chronic kidney disease in native and transplanted kidneys. There is limited evidence on the association on dietary intake with renal allograft function. Mechanisms of major nutrients and dietary patterns with focusing on a plant-based diet related to kidney transplant health and longevity are reviewed.

RECENT FINDINGS

High dietary protein intake may adversely affect renal allograft. Low protein plant-focused diets such as Dietary Approaches to Stop Hypertension, plant-dominant low-protein diet and Mediterranean diets appear associated with favorable outcomes in slowing renal allograft function decline. The mechanism may be related to a change in renal hemodynamic by decreasing glomerular hyperfiltration from low dietary protein intake and plant-based ingredients. Recent observational studies of association between dietary protein intake and kidney allograft outcomes are conflicting. Although strong evidence is still lacking, a low protein diet of 0.6-0.8 g/kg/day with at least 50% of the protein source from plant-based components in kidney transplant recipients with stable kidney allograft function should be considered as the dietary target.

SUMMARY

Dietary intervention with low-protein plant-focused meals may improve outcomes in kidney transplant recipients, but the evidence remains limited and further studies are warranted.

Nutritional Approaches for the Management of Metabolic Acidosis in Chronic Kidney Disease

Metabolic acidosis is a severe complication of chronic kidney disease (CKD) which is associated with nefarious impairments such as bone demineralization, muscle wasting, and hormonal alterations, for example, insulin resistance. Whilst it is possible to control this condition with alkali treatment, consisting in the oral administration of sodium citrate or sodium bicarbonate, this type of intervention is not free from side effects. On the contrary, opting for the implementation of a targeted dietetic-nutritional treatment for the control of CKD metabolic acidosis also comes with a range of additional benefits such as lipid profile control, increased vitamins, and antioxidants intake. In our review, we evaluated the main dietary-nutritional regimens useful to counteract metabolic acidosis, such as the Mediterranean diet, the alkaline diet, the low-protein diet, and the vegan low-protein diet, analyzing the potentialities and limits of every dietary-nutritional treatment. Literature data suggest that the Mediterranean and alkaline diets represent a valid nutritional approach in the prevention and correction of metabolic acidosis in CKD early stages, while the low-protein diet and the vegan low-protein diet are more effective in CKD advanced stages. In conclusion, we propose that tailored nutritional approaches should represent a valid therapeutic alternative to counteract metabolic acidosis.

Dietary Plant Protein and Mortality Among Patients Receiving Maintenance Hemodialysis: A Cohort Study

RATIONALE & OBJECTIVE

Although greater dietary intake of protein has been associated with beneficial health effects among patients receiving maintenance hemodialysis (MHD), the effects of plant protein intake are less certain. We studied the association of the proportion of protein intake derived from plant sources with the risk of mortality among patients receiving MHD and explored factors that may modify these associations.

STUDY DESIGN

Prospective observational cohort study.

SETTING & PARTICIPANTS

1,119 Chinese hemodialysis patients aged over 18 years receiving MHD in 2014-2015.

PREDICTORS

The proportion of plant protein intake to total protein intake.

OUTCOMES

All-cause mortality and cardiovascular disease (CVD) mortality.

ANALYTICAL APPROACH

Segmented regression models were fit to examine the association of plant protein intake proportion with the risk of all-cause mortality and CVD mortality. Multivariable-adjusted Cox proportional and cause-specific hazards models were used to estimate the hazard ratios (HR) and 95% CI for these outcomes.

RESULTS

The means of plant protein intake normalized to ideal body weight and plant protein intake proportion were 0.6±0.2 (SD) g/kg per day and 0.538±0.134, respectively. During a median follow-up period of 28.0 months, 249 deaths occurred, with 146 of these deaths resulting from CVD. Overall, there was a U-shaped association between plant protein intake proportion and the risk of all-cause mortality, with an inflection point at 45%. Among patients with a plant protein intake proportion<45%, there was a 17% lower rate of mortality with each 5% greater plant protein intake proportion (HR, 0.83 [95% CI, 0.73-0.96]). Among patients with plant protein intake proportion≥45%, there was a 9% greater rate of mortality with each 5% greater plant protein intake proportion. A similar U-shaped association was observed for CVD mortality, with an inflection point at 44%.

LIMITATIONS

Observational study, potential unmeasured confounding.

CONCLUSIONS

There was a U-shaped association between plant protein intake proportion and the risk of all-cause and cardiovascular mortality in MHD patients. If confirmed, these findings suggest a potential avenue to improve outcomes in this patient population.

Is protein the forgotten ingredient: Effects of higher compared to lower protein diets on cardiometabolic risk factors. A systematic review and meta-analysis of randomised controlled trials

BACKGROUND AND AIMS

Higher protein (HP) diets may lead to lower cardiometabolic risk, compared to lower protein (LP) diets. This systematic review and meta-analysis aims to investigate the effects of HP versus LP diets on cardiometabolic risk factors in adults, using the totality of the current evidence from randomised controlled trials (RCTs).

METHODS

Systematic searches were conducted in electronic databases, up to November 2020. Random effects meta-analyses were conducted to pool the standardised mean differences (SMD) and 95% confidence intervals (CI). The main outcomes were weight loss, body mass index (BMI), waist circumference, fat mass, systolic and diastolic BP, total cholesterol, HDL-and LDL-cholesterol, triacylglycerol, fasting glucose and insulin, and glycated haemoglobin.

RESULTS

Fifty-seven articles reporting on 54 RCTs were included, involving 4344 participants (65% female, mean age: 46 (SD 10) years, mean BMI: 33 (SD 3) kg/m²), with a mean study duration of 18 weeks (range: 4 to 156 weeks). Compared to LP diets (range protein (E%):10-23%), HP diets (range protein (E%): 20-45%) led to more weight loss (SMD -0.13, 95% CI: -0.23, -0.03), greater reductions in fat mass (SMD -0.14, 95% CI: -0.24, -0.04), systolic BP (SMD -0.12, 95% CI: -0.21, -0.02), total cholesterol (SMD -0.11, 95% CI: -0.19, -0.02), triacylglycerol (SMD -0.22, 95% CI: -0.30, -0.14) and insulin (SMD -0.12, 95% CI: -0.22, -0.03). No significant differences were observed for the other outcomes.

CONCLUSIONS

Higher protein diets showed small, but favourable effects on weight loss, fat mass loss, systolic blood pressure, some lipid outcomes and insulin, compared to lower protein diets.

Gluten intake and metabolic health: conflicting findings from the UK Biobank

PURPOSE

The impact of gluten intake on metabolic health in subjects without celiac disease is unclear. The present study aimed to assess the association between gluten intake and body fat percentage (primary objective), as well as a broad set of metabolic health markers.

METHODS

Gluten intake was estimated in 39,927 participants of the UK Biobank who completed a dietary questionnaire for assessment of previous 24-h dietary intakes. Multiple linear regression analyses were performed between gluten intake and markers of metabolic health with Holm adjustment for multiple comparisons.

RESULTS

Median gluten intake was 9.7 g/day (male: 11.7 g/day; female: 8.2 g/day; p < 0.0001). In multiple linear regression analysis, association between gluten intake and percentage body fat was negative in males (β = - 0.028, p = 0.0020) and positive in females (β = 0.025, p = 0.0028). Furthermore, gluten intake was a negative predictor of total cholesterol (male: β = - 0.031, p = 0.0154; female: β = - 0.050, p < 0.0001), high-density lipoprotein cholesterol (male: β = - 0.052, p < 0.0001; female: β = - 0.068, p < 0.0001), and glomerular filtration rate (sexes combined: β = - 0.031, p < 0.0001) in both sexes. In females only, gluten intake was positively associated with waist circumference (β = 0.041, p < 0.0001), waist-to-height ratio (β = 0.040, p < 0.0001), as well as body mass index (β = 0.043, p < 0.0001), and negatively related to low-density lipoprotein cholesterol (β = - 0.035, p = 0.0011). A positive association between gluten intake and triglycerides was observed in males only (β = 0.043, p = 0.0001).

CONCLUSION

This study indicates that gluten intake is associated with markers of metabolic health. However, all associations are weak and not clinically meaningful. Limiting gluten intake is unlikely to provide metabolic health benefits for a population in total.

Dietary protein intake, kidney function, and survival in a nationally representative cohort

BACKGROUND

High-protein diets (e.g., Paleo, Atkins, South Beach, ketogenic) have gained popularity as a means to promote weight loss and avoid excess carbohydrate consumption. Yet in chronic kidney disease (CKD) patients, evidence suggests low dietary protein intake (DPI) leads to attenuation of kidney function decline, although concerns remain for risk of protein-energy wasting.

OBJECTIVES

To examine associations of DPI with mortality in a nationally representative cohort of US adults, stratified by kidney function.

METHODS

We examined the association between daily DPI scaled to actual body weight (ABW), ascertained by 24-h dietary recall, with all-cause mortality among 27,604 continuous NHANES adult participants (1999-2010), stratified according to impaired versus normal kidney function (estimated glomerular filtration rates <60 compared with ≥60 ml/min/1.72 m2, respectively), using multivariable Cox models. We also examined the relation between high biological value (HBV) protein consumption with mortality.

RESULTS

In participants with impaired kidney function, a high DPI of ≥1.4 g/kg ABW/day was associated with higher mortality, while lower DPI levels were not associated with mortality (reference, 0.6 to <1.0 g/kg ABW/day): the adjusted HRs (aHRs) were 1.09 (95% CI: 0.90, 1.32), 1.03 (95% CI: 0.82, 1.29), and 1.37 (95% CI: 1.02, 1.85) for DPI <0.6, 1.0 to <1.4, and ≥1.4 g/kg ABW/day, respectively. Yet in participants with normal kidney function, a low DPI of <0.6 g/kg ABW/day was associated with higher mortality, whereas higher DPI levels were not associated with death: the aHRs were 1.18 (95% CI: 1.04, 1.34), 0.92 (95% CI: 0.81, 1.04), and 0.99 (95% CI: 0.85, 1.16) for DPI <0.6, 1.0 to <1.4, and ≥1.4 g/kg ABW/day, respectively. The highest 2 tertiles of HBV consumption were associated with higher mortality in participants with impaired kidney function.

CONCLUSIONS

Among participants with impaired kidney function, a higher DPI and greater HBV consumption were associated with higher mortality, whereas a lower DPI was associated with higher mortality in those with normal kidney function. Further studies are needed to elucidate the specific pathways between higher DPI and mortality in CKD.

Effects of dietary macronutrients on serum urate: results from the OmniHeart trial

BACKGROUND

Dietary recommendations to prevent gout emphasize a low-purine diet. Recent evidence suggests that the Dietary Approaches to Stop Hypertension (DASH) diet reduces serum urate while also improving blood pressure and lipids.

OBJECTIVE

To compare the effects of DASH-style diets emphasizing different macronutrient proportions on serum urate reduction.

METHODS

We conducted a secondary analysis of the Optimal Macronutrient Intake Trial to Prevent Heart Disease feeding study, a 3-period, crossover design, randomized trial of adults with prehypertension or hypertension. Participants were provided with 3 DASH-style diets in random order, each for 6 wk. Each DASH-style diet emphasized different macronutrient proportions: a carbohydrate-rich (CARB) diet, a protein-rich (PROT) diet, and an unsaturated fat-rich (UNSAT) diet. In the PROT diet, approximately half of the protein came from plant sources. We compared the effects of these diets on serum urate at weeks 4 and 6 of each feeding period.

RESULTS

Of the 163 individuals included in the final analysis, the mean serum urate at baseline was 5.1 mg/dL. Only the PROT diet reduced serum urate from baseline at the end of the 6-wk feeding period (-0.16 mg/dL; 95% CI: -0.28, -0.04; P = 0.007). Neither the CARB diet (-0.03 mg/dL; 95% CI: -0.14, 0.09; P = 0.66) nor the UNSAT diet (-0.01 mg/dL; 95% CI: -0.12, 0.09; P = 0.78) reduced serum urate from baseline. The PROT diet lowered serum urate by 0.12 mg/dL (95% CI: -0.20, -0.03; P = 0.006) compared with CARB and by 0.12 mg/dL (95% CI: -0.20, -0.05; P = 0.002) compared with UNSAT.

CONCLUSIONS

A DASH-style diet emphasizing plant-based protein lowered serum urate compared with those emphasizing carbohydrates or unsaturated fat. Future trials should test the ability of a DASH-style diet emphasizing plant-based protein to lower serum urate and prevent gout flares in patients with gout. This trial was registered at clinicaltrials.gov as NCT00051350.

The impact of type of dietary protein, animal versus vegetable, in modifying cardiometabolic risk factors: A position paper from the International Lipid Expert Panel (ILEP)

Proteins play a crucial role in metabolism, in maintaining fluid and acid-base balance and antibody synthesis. Dietary proteins are important nutrients and are classified into: 1) animal proteins (meat, fish, poultry, eggs and dairy), and, 2) plant proteins (legumes, nuts and soy). Dietary modification is one of the most important lifestyle changes that has been shown to significantly decrease the risk of cardiovascular (CV) disease (CVD) by attenuating related risk factors. The CVD burden is reduced by optimum diet through replacement of unprocessed meat with low saturated fat, animal proteins and plant proteins. In view of the available evidence, it has become acceptable to emphasize the role of optimum nutrition to maintain arterial and CV health. Such healthy diets are thought to increase satiety, facilitate weight loss, and improve CV risk. Different studies have compared the benefits of omnivorous and vegetarian diets. Animal protein related risk has been suggested to be greater with red or processed meat over and above poultry, fish and nuts, which carry a lower risk for CVD. In contrast, others have shown no association of red meat intake with CVD. The aim of this expert opinion recommendation was to elucidate the different impact of animal vs vegetable protein on modifying cardiometabolic risk factors. Many observational and interventional studies confirmed that increasing protein intake, especially plant-based proteins and certain animal-based proteins (poultry, fish, unprocessed red meat low in saturated fats and low-fat dairy products) have a positive effect in modifying cardiometabolic risk factors. Red meat intake correlates with increased CVD risk, mainly because of its non-protein ingredients (saturated fats). However, the way red meat is cooked and preserved matters. Thus, it is recommended to substitute red meat with poultry or fish in order to lower CVD risk. Specific amino acids have favourable results in modifying major risk factors for CVD, such as hypertension. Apart from meat, other animal-source proteins, like those found in dairy products (especially whey protein) are inversely correlated to hypertension, obesity and insulin resistance.

A prospective study on total protein, plant protein and animal protein in relation to the risk of incident chronic kidney disease

BACKGROUND

The link between dietary protein intake and the risk of kidney dysfunction is always a challenging issue. This study aimed to investigate the relationship between total protein, plant protein, and animal protein intake with the risk of incident chronic kidney disease (CKD).

METHODS

This study was performed on 1639 adults aged ≥27 years who participated in the Tehran Lipid and Glucose Study. Dietary data were evaluated using a valid and reliable semi-quantitative food frequency questionnaire (FFQ). Total protein content, plant protein, and animal protein of each participant were calculated. Glomerular filtration rate (GFR) less than 60 mL / min / 1.73 m² has been considered as the definition of CKD. Odds Ratio (OR) was calculated using logistic regression to show the association between the risk of incident CKD and dietary exposures.

RESULTS

After adjusting for age, sex, body mass index, smoking, total energy intake, total fiber intake, dietary fat, physical activity, diabetes, and hypertension, there was no significant association of total protein and animal protein consumptions with the incidence of CKD. After adjustment for confounders, compared with the lowest tertile of plant protein consumption, OR of incident CKD in the highest tertile was 0.29 (95% confidence interval [95% CI] 0.15 to 0.55) with a significant trend (P for trend < 0.001).

CONCLUSION

The results of this study confirmed an inverse association between plant protein intake and the risk of incident CKD, which demonstrates the protective role of plant-based protein in a diet on kidney function.

Increasing vegetable intake 400 g/day to control body weight and lipid profile in overweight hyperlipidemia menopausal women

Background: Indonesia suffers growing health problems such as obesity, diabetes, and other metabolic syndromes with dietary habit as one of risk factors. To control the lipid and glycaemic profile, high fibre intake has been recommended. This study administered 400g/day vegetable intake with its fiber contents and observed the effects in lipid profile and glycaemic control. Design: A parallel study of 30 pairs of menopausal women match paired in overweight, menopause, hyperlipidaemia, age, etc randomly divided into two groups (vegetable and control). The baseline data obtained from questionnaire and preliminary bloodwithdrawn of consented participants, then matched the characteristics included the results of lipid profile and glycated albumin. The administration was conducted for 21days by providing 400g/day of vegetable to the vegetable group subjects. Nutrition assessments were conducted at the baseline, middle, and final period. The data were analysed by using the unpaired and paired t-test. Results: Significant results (p<0.05) were seen in biochemical variables in the lipid profile of total cholesterol, LDL cholesterol, and HDL cholesterol and body weight and BMI within the vegetable group. Significant results for the same variables were shown between vegetable and control group at the final data (p<0.05). The nutrition assessments result showed significances (p<0.05) within vegetable group and between two groups on the final data. After 21 days, significant decreases were found on the intakes of energy, lipids, carbohydrates (p<0.05), while vegetable intake and fiber intake showed significant increases (p<0.05). Conclusion: These data suggest that maintaining a healthy diet of 400g/d vegetable can be effective in weight management and lipid profile control.

Mediterranean Style Diet and Kidney Function Loss in Kidney Transplant Recipients

BACKGROUND AND OBJECTIVES

Despite improvement of short-term graft survival over recent years, long-term graft survival after kidney transplantation has not improved. Studies in the general population suggest the Mediterranean diet benefits kidney function preservation. We investigated whether adherence to the Mediterranean diet is associated with kidney outcomes in kidney transplant recipients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We included 632 adult kidney transplant recipients with a functioning graft for ≥1 year. Dietary intake was inquired using a 177-item validated food frequency questionnaire. Adherence to the Mediterranean diet was assessed using a nine-point Mediterranean Diet Score. Primary end point of the study was graft failure and secondary end points included kidney function decline (doubling of serum creatinine or graft failure) and graft loss (graft failure or death with a functioning graft). Cox regression analyses were used to prospectively study the associations of the Mediterranean Diet Score with study end points.

RESULTS

During median follow-up of 5.4 (interquartile range, 4.9-6.0) years, 76 participants developed graft failure, 119 developed kidney function decline, and 181 developed graft loss. The Mediterranean Diet Score was inversely associated with all study end points (graft failure: hazard ratio [HR], 0.68; 95% confidence interval [95% CI], 0.50 to 0.91; kidney function decline: HR, 0.68; 95% CI, 0.55 to 0.85; and graft loss: HR, 0.74; 95% CI, 0.63 to 0.88 per two-point increase in Mediterranean Diet Score) independent of potential confounders. We identified 24-hour urinary protein excretion and time since transplantation to be an effect modifier, with stronger inverse associations between the Mediterranean Diet Score and kidney outcomes observed in participants with higher urinary protein excretion and participants transplanted more recently.

CONCLUSIONS

Adherence to the Mediterranean diet is associated with better kidney function outcomes in kidney transplant recipients.

Associations Between Linoleic Acid Intake and Incident Type 2 Diabetes Among U.S. Men and Women

OBJECTIVE

To investigate the association between intakes of n-6 polyunsaturated fatty acids (PUFAs) and type 2 diabetes risk in three prospective cohort studies of U.S. men and women.

RESEARCH DESIGN AND METHODS

We followed 83,648 women from the Nurses' Health Study (NHS) (1980-2012), 88,610 women from NHSII (1991-2013), and 41,771 men from the Health Professionals Follow-Up Study (HPFS) (1986-2012). Dietary data were collected every 2-4 years by using validated food-frequency questionnaires. Self-reported incident diabetes, identified biennially, was confirmed by using a validated supplementary questionnaire.

RESULTS

During 4.93 million person-years of follow-up, 18,442 type 2 diabetes cases were documented. Dietary n-6 PUFAs accounted for 4.4-6.8% of total energy, on average, and consisted primarily of linoleic acid (LA) (≥98%). In multivariate-adjusted models, hazard ratios (95% CIs) of type 2 diabetes risk comparing extreme n-6 PUFA quintiles (highest vs. lowest) were 0.91 (0.85, 0.96) (P _trend = 0.002) for total n-6 PUFAs and 0.92 (0.87, 0.98) (P _trend = 0.01) for LA. In an isocaloric substitution model, diabetes risk was 14% (95% CI 5%, 21%) (P = 0.002) lower when LA isocalorically replaced saturated fats (5% of energy), 17% (95% CI 9%, 24%) (P < 0.001) lower for trans fats (2% of energy), or 9% (95% CI 17%, 0.1%) (P = 0.047) lower for carbohydrates (5% of energy). Replacing n-3 PUFAs or monounsaturated fats with LA was not significantly associated with type 2 diabetes risk.

CONCLUSIONS

Our study provides additional evidence that LA intake is inversely associated with risk of type 2 diabetes, especially when replacing saturated fatty acids, trans fats, or carbohydrates.

Non-Celiac Gluten Sensitivity: A Review

Background and objectives: Grain food consumption is a trigger of gluten related disorders: celiac disease, non-celiac gluten sensitivity (NCGS) and wheat allergy. They demonstrate with non-specific symptoms: bloating, abdominal discomfort, diarrhea and flatulence. Aim: The aim of the review is to summarize data about pathogenesis, symptoms and criteria of NCGS, which can be helpful for physicians. Materials and Methods: The PubMed and Google Scholar databases were searched in January 2019 with phrases: 'non-celiac gluten sensitivity', non-celiac gluten sensitivity', non-celiac wheat gluten sensitivity', non-celiac wheat gluten sensitivity', and gluten sensitivity'. More than 1000 results were found. A total of 67 clinical trials published between 1989 and 2019 was scanned. After skimming abstracts, 66 articles were chosen for this review; including 26 clinical trials. Results: In 2015, Salerno Experts' Criteria of NCGS were published. The Salerno first step is assessing the clinical response to gluten free diet (GFD) and second is measuring the effect of reintroducing gluten after a period of treatment with GFD. Several clinical trials were based on the criteria. Conclusions: Symptoms of NCGS are similar to other gluten-related diseases, irritable bowel syndrome and Crohn's disease. With Salerno Experts' Criteria of NCGS, it is possible to diagnose patients properly and give them advice about nutritional treatment.

Changes in Kidney Function Do Not Differ between Healthy Adults Consuming Higher- Compared with Lower- or Normal-Protein Diets: A Systematic Review and Meta-Analysis

Background

Higher-protein (HP) diets are advocated for several reasons, including mitigation of sarcopenia, but their effects on kidney function are unclear.

Objective

This meta-analysis was conducted to determine the effect of HP intakes on kidney function in healthy adults.

Methods

We conducted a systematic review and meta-analysis of trials comparing HP (≥1.5 g/kg body weight or ≥20% energy intake or ≥100 g protein/d) with normal- or lower-protein (NLP; ≥5% less energy intake from protein/d compared with HP group) intakes on kidney function. Medline and EMBASE databases were searched. Randomized controlled trials comparing the effects of HP with NLP (>4 d duration) intakes on glomerular filtration rate (GFR) in adults without kidney disease were included.

Results

A total of 2144 abstracts were reviewed, with 40 articles selected for full-text review; 28 of these were analyzed and included data from 1358 participants. Data were analyzed using random-effects meta-analysis (RevMan 5; The Cochrane Collaboration), meta-regression (STATA; StataCorp), and dose-response analysis (Prism; GraphPad). Analyses were conducted using postintervention (post) GFR and the change in GFR from preintervention to post. The post-only comparison showed a trivial effect for GFR to be higher after HP intakes [standardized mean difference (SMD): 0.19; 95% CI: 0.07, 0.31; P = 0.002]. The change in GFR did not differ between interventions (SMD: 0.11; 95% CI: -0.05, 0.27; P = 0.16). There was a linear relation between protein intake and GFR in the post-only comparison (r = 0.332, P = 0.03), but not between protein intake and the change in GFR (r = 0.184, P = 0.33). The main limitation of the current analysis is the unclear risk of selection bias of the included trials.

Conclusions

Postintervention GFR comparisons indicate that HP diets result in higher GFRs; however, when changes in GFR were compared, dietary protein had no effect. Our analysis indicates that HP intakes do not adversely influence kidney function on GFR in healthy adults.

Gluten intake and risk of type 2 diabetes in three large prospective cohort studies of US men and women

AIMS/HYPOTHESIS

We investigated the association between gluten intake and long-term type 2 diabetes risk among Americans.

METHODS

We followed women from the Nurses' Health Study (NHS, n = 71,602, 1984-2012) and NHS II (n = 88,604, 1991-2013) and men from the Health Professionals Follow-Up Study (HPFS, n = 41,908, 1986-2012). Gluten intake was estimated using a validated food frequency questionnaire every 2-4 years. Incident type 2 diabetes was defined as self-reported physician-diagnosed diabetes confirmed using a supplementary questionnaire.

RESULT

Gluten intake was strongly correlated with intakes of carbohydrate components, especially refined grains, starch and cereal fibre (Spearman correlation coefficients >0.6). During 4.24 million years of follow-up, 15,947 people were confirmed to have type 2 diabetes. After multivariate adjustment, pooled HRs and 95% CIs for type 2 diabetes, from low to high gluten quintiles, were (p_trend < 0.001): 1 (reference); 0.89 (0.85, 0.93); 0.84 (0.80, 0.88); 0.78 (0.74, 0.82) and 0.80 (0.76, 0.84). The association was slightly weakened after further adjusting for cereal fibre, with pooled HRs (95% CIs) of (p_trend < 0.001): 1 (reference); 0.91 (0.87, 0.96); 0.88 (0.83, 0.93); 0.83 (0.78, 0.88) and 0.87 (0.81, 0.93). Dose-response analysis supported a largely linear inverse relationship between gluten intake up to 12 g/day and type 2 diabetes. The association between gluten intake and type 2 diabetes was stronger when intake of added bran was also higher (p_interaction = 0.02).

CONCLUSIONS/INTERPRETATION

Gluten intake is inversely associated with type 2 diabetes risk among largely healthy US men and women. Limiting gluten in the diet is associated with lower intake of cereal fibre and possibly other beneficial nutrients that contribute to good health.

A Systematic Review of Renal Health in Healthy Individuals Associated with Protein Intake above the US Recommended Daily Allowance in Randomized Controlled Trials and Observational Studies

A systematic review was used to identify randomized controlled trials (RCTs) and observational epidemiologic studies (OBSs) that examined protein intake consistent with either the US RDA (0.8 g/kg or 10-15% of energy) or a higher protein intake (≥20% but <35% of energy or ≥10% higher than a comparison intake) and reported measures of kidney function. Studies (n = 26) of healthy, free-living adults (>18 y old) with or without metabolic disease risk factors were included. Studies of subjects with overt disease, such as chronic kidney, end-stage renal disease, cancer, or organ transplant, were excluded. The most commonly reported variable was glomerular filtration rate (GFR), with 13 RCTs comparing GFRs obtained with normal and higher protein intakes. Most (n = 8), but not all (n = 5), RCTs reported significantly higher GFRs in response to increased protein intake, and all rates were consistent with normal kidney function in healthy adults. The evidence from the current review is limited and inconsistent with regard to the role of protein intake and the risk of kidney stones. Increased protein intake had little or no effect on blood markers of kidney function. Evidence reported here suggests that protein intake above the US RDA has no adverse effect on blood pressure. All included studies were of moderate to high risk of bias and, with the exception of 2 included cohorts, were limited in duration (i.e. <6 mo). Data in the current review are insufficient to determine if increased protein intake from a particular source, i.e., plant or animal, influences kidney health outcomes. These data further indicate that, at least in the short term, higher protein intake within the range of recommended intakes for protein is consistent with normal kidney function in healthy individuals.

Effect of the gluten-free diet on cardiovascular risk factors in patients with coeliac disease: A systematic review

BACKGROUND AND AIMS

A gluten-free diet (GFD), the mainstay of treatment for celiac disease, is being increasingly adopted by people without this condition. The long-term health effects of this diet, apart from its beneficial effect on enteropathy in celiac disease, are unclear. Concerns exist that the GFD may result in micronutrient deficiencies, increased exposure to toxins such as arsenic, and an increased cardiovascular risk. This systematic review addresses the effect of the GFD on several modifiable cardiovascular risk factors.

METHODS

A systematic search of the literature addressing the GFD and blood pressure, glycaemia, body mass index, waist circumference, and serum lipids in patients before and after adoption of a GFD was conducted using the MEDLINE, EMBASE, PSYCInfo, and the Cochrane Central Register of Controlled Trials (CENTRAL) databases. Two authors performed abstract and full text screening, and quality assessment.

RESULTS

A total of 5372 articles were identified, from which 27 were included. Lack of control groups in all but one study prevented meta-analysis of results. Overall study quality was low and restricted to patients with celiac disease. Consistent findings across studies included an increase in total cholesterol, high density lipoprotein, fasting glycaemia, and body mass index (while remaining within the healthy weight range). Significant changes in low density lipoprotein, triglycerides, and blood pressure were not consistently reported.

CONCLUSIONS

A GFD alters certain cardiovascular risk factors in patients with celiac disease, but the overall effect on cardiovascular risk is unclear. Further studies are warranted.

Structural Basis of Bioactivity of Food Peptides in Promoting Metabolic Health

Bioactive peptides have many structural features that enable them to become functional in controlling several biological processes in the body, especially those related to metabolic health. This chapter provides an overview of the multiple targets of food-derived peptides against metabolic health problems (e.g., hypertension, dyslipidemia, hyperglycemia, oxidative stress) and discusses the importance of structural chemistry in determining the bioactivities of peptides and protein hydrolysates.

Dietary Patterns and Clinical Outcomes in Chronic Kidney Disease: The CKD.QLD Nutrition Study

OBJECTIVE

Emerging evidence suggests that dietary patterns are associated with survival in people with chronic kidney disease (CKD). This study evaluated the relationship between dietary habits and renal-related clinical outcomes in an established CKD cohort.

DESIGN

Prospective cohort study.

SETTING

Three outpatient nephrology clinics in Queensland, Australia.

SUBJECTS

A total of 145 adult patients with Stage 3 or 4 CKD (estimated glomerular filtration rate 15-59 mL/minute/1.73 m²).

INTERVENTION

Dietary intake was measured using 24-hour recall and the HeartWise Dietary Habits Questionnaire (DHQ), which evaluates 10 components of dietary patterns in relation to cooking habits and intake of food groups.

MAIN OUTCOME MEASURE

The primary outcome was a composite end point of all-cause mortality, commencement of dialysis, and doubling of serum creatinine. Secondary outcome was all-cause mortality alone. Multivariate cox regression analyses calculated hazard ratios (HRs) for associations between DHQ domains and occurrence of composite outcome and adjusted for confounders, including comorbidities and renal function.

RESULTS

Over a median follow-up of 36 months, 32% (n = 47) reached the composite end point, of which 21% died (n = 30). Increasing DHQ score was associated with a lower risk of the composite end point with increasing intake of fruits and vegetables (HR: 0.61; 95% CI, 0.39-0.94) and limiting alcohol consumption (HR, 0.79; 95% CI: 0.65-0.96). For the secondary outcome of all-cause mortality, there was a significant association with adequate intake of fruits and vegetables (HR: 0.35; 95% CI, 0.15-0.83).

CONCLUSION

Healthy dietary patterns consisting of adequate fruits and vegetables and limited alcohol consumption are associated with a delay in CKD progression and improved survival in patients with Stage 3 or 4 CKD.

Effect of increased protein intake on renal acid load and renal hemodynamic responses

Increased protein intake versus maltodextrin intake for 4 weeks lowers blood pressure. Concerns exist that high‐protein diets reduce renal function. Effects of acute and 4‐week protein intake versus maltodextrin intake on renal acid load, glomerular filtration rate and related parameters were compared in this study. Seventy‐nine overweight individuals with untreated elevated blood pressure and normal kidney function were randomized to consume a mix of protein isolates (60 g/day) or maltodextrin (60 g/day) for 4 weeks in energy balance. Twenty‐four‐hour urinary potential renal acid load (uPRAL) was compared between groups. A subgroup (maltodextrin N = 27, protein mix N = 25) participated in extra test days investigating fasting levels and postprandial effects of meals supplemented with a moderate protein‐ or maltodextrin‐load on glomerular filtration rate, effective renal plasma flow, plasma renin, aldosterone, pH, and bicarbonate. uPRAL was significantly higher in the protein group after 4 weeks (P ≤ 0.001). Postprandial filtration fraction decreased further after the protein‐supplemented breakfast than after the maltodextrin‐supplemented breakfast after 4 weeks of supplementation (P ≤ 0.001). Fasting and postprandial levels of glomerular filtration rate, effective renal plasma flow, renin, aldosterone, angiotensin‐converting enzyme, pH and bicarbonate did not differ between groups. In conclusion, 4 weeks on an increased protein diet (25% of energy intake) increased renal acid load, but did not affect renal function. Postprandial changes, except for filtration fraction, also did not differ between groups. These data suggest that a moderate increase in protein intake by consumption of a protein mix for 4 weeks causes no (undesirable) effects on kidney function in overweight and obese individuals with normal kidney function.

Effects of Lowering Glycemic Index of Dietary Carbohydrate on Plasma Uric Acid Levels: The OmniCarb Randomized Clinical Trial

OBJECTIVE

The effects of carbohydrates on plasma uric acid levels are a subject of controversy. We determined the individual and combined effects of carbohydrate quality (the glycemic index) and quantity (the proportion of total daily energy [percentage of carbohydrates]) on uric acid levels.

METHODS

We conducted a randomized, crossover trial of 4 different diets in overweight or obese adults without cardiovascular disease (n = 163). Participants consumed each of 4 diets over a 5-week period, each of which was separated by a 2-week washout period. Body weight was kept constant. The 4 diets were high glycemic index (≥65) with high percentage of carbohydrates (58% kcal), low glycemic index (≤45) with low percentage of carbohydrates (40% kcal), low glycemic index with high percentage of carbohydrates, and high glycemic index with low percentage of carbohydrates. Plasma uric acid levels were measured at baseline and after completion of each 5-week period for comparison between the 4 diets.

RESULTS

Of the 163 study participants, 52% were women and 50% were non-Hispanic African American subjects; their mean age was 52.6 years, and their mean ± SD uric acid level was 4.7 ± 1.2 mg/dl. Reducing the glycemic index lowered uric acid levels when the percentage of carbohydrates was low (-0.24 mg/dl; P < 0.001) or high (-0.17 mg/dl; P < 0.001). Reducing the percentage of carbohydrates marginally increased the uric acid level only when the glycemic index was high (P = 0.05). The combined effect of lowering the glycemic index and increasing the percentage of carbohydrates was -0.27 mg/dl (P < 0.001). This effect was observed even after adjustment for concurrent changes in kidney function, insulin sensitivity, and products of glycolysis.

CONCLUSION

Reducing the glycemic index lowers uric acid levels. Future studies should examine whether reducing the glycemic index can prevent gout onset or flares.

Gut Microbiota and Lifestyle Interventions in NAFLD

The human digestive system harbors a diverse and complex community of microorganisms that work in a symbiotic fashion with the host, contributing to metabolism, immune response and intestinal architecture. However, disruption of a stable and diverse community, termed "dysbiosis", has been shown to have a profound impact upon health and disease. Emerging data demonstrate dysbiosis of the gut microbiota to be linked with non-alcoholic fatty liver disease (NAFLD). Although the exact mechanism(s) remain unknown, inflammation, damage to the intestinal membrane, and translocation of bacteria have all been suggested. Lifestyle intervention is undoubtedly effective at improving NAFLD, however, not all patients respond to these in the same manner. Furthermore, studies investigating the effects of lifestyle interventions on the gut microbiota in NAFLD patients are lacking. A deeper understanding of how different aspects of lifestyle (diet/nutrition/exercise) affect the host-microbiome interaction may allow for a more tailored approach to lifestyle intervention. With gut microbiota representing a key element of personalized medicine and nutrition, we review the effects of lifestyle interventions (diet and physical activity/exercise) on gut microbiota and how this impacts upon NAFLD prognosis.

Remission of pre-diabetes to normal glucose tolerance in obese adults with high protein versus high carbohydrate diet: randomized control trial

OBJECTIVE

Remission of pre-diabetes to normal is an important health concern which has had little success in the past. This study objective was to determine the effect on remission of pre-diabetes with a high protein (HP) versus high carbohydrate (HC) diet and effects on metabolic parameters, lean and fat body mass in prediabetic, obese subjects after 6 months of dietary intervention.

RESEARCH DESIGN AND METHODS

We recruited and randomized 24 pre-diabetes women and men to either a HP (30% protein, 30% fat, 40% carbohydrate; n=12) or HC (15% protein, 30% fat, 55% carbohydrate; n=12) diet feeding study for 6 months in this randomized controlled trial. All meals were provided to subjects for 6 months with daily food menus for HP or HC compliance with weekly food pick-up and weight measurements. At baseline and after 6 months on the respective diets oral glucose tolerance and meal tolerance tests were performed with glucose and insulin measurements and dual energy X-ray absorptiometry scans.

RESULTS

After 6 months on the HP diet, 100% of the subjects had remission of their pre-diabetes to normal glucose tolerance, whereas only 33.3% of subjects on the HC diet had remission of their pre-diabetes. The HP diet group exhibited significant improvement in (1) insulin sensitivity (p=0.001), (2) cardiovascular risk factors (p=0.04), (3) inflammatory cytokines (p=0.001), (4) oxidative stress (p=0.001), (5) increased percent lean body mass (p=0.001) compared with the HC diet at 6 months.

CONCLUSIONS

This is the first dietary intervention feeding study, to the best of our knowledge, to report 100% remission of pre-diabetes with a HP diet and significant improvement in metabolic parameters and anti-inflammatory effects compared with a HC diet at 6 months.

TRIAL REGISTRATION NUMBER

NCT0164284.

The Associations of Plant Protein Intake With All-Cause Mortality in CKD

BACKGROUND

Plant protein intake is associated with lower production of uremic toxins and lower serum phosphorus levels. Therefore, at a given total protein intake, a higher proportion of dietary protein from plant sources might be associated with lower mortality in chronic kidney disease.

STUDY DESIGN

Observational study.

SETTINGS & PARTICIPANTS

14,866 NHANES III participants 20 years or older without missing data for plant and animal protein intake and mortality.

PREDICTORS

Plant protein to total protein ratio and total plant protein intake. Patients were stratified by estimated glomerular filtration rate (eGFR)<60 or ≥60mL/min/1.73m(2).

OUTCOMES

All-cause mortality.

MEASUREMENTS

Plant and total protein intakes were estimated from 24-hour dietary recalls. Mortality was ascertained by probabilistic linkage with National Death Index records through December 31, 2000.

RESULTS

Mean values for plant protein intake and plant protein to total protein ratio were 24.6±13.2 (SD) g/d and 33.0% ± 14.0%, respectively. The prevalence of eGFRs<60mL/min/1.73m(2) was 4.9%. There were 2,163 deaths over an average follow-up of 8.4 years. Adjusted for demographics, smoking, alcohol use, comorbid conditions, body mass index, calorie and total protein intake, and physical inactivity, each 33% increase in plant protein to total protein ratio was not associated with mortality (HR, 0.88; 95% CI, 0.74-1.04) in the eGFR≥60mL/min/1.73m(2) subpopulation, but was associated with lower mortality risk (HR, 0.77; 95% CI, 0.61-0.96) in the eGFR<60mL/min/1.73m(2) subpopulation. In sensitivity analyses, results were similar in those with eGFR<60mL/min/1.73m(2) defined by serum cystatin C level.

LIMITATIONS

Whether results are related to plant protein itself or to other factors associated with more plant-based diets is difficult to establish.

CONCLUSIONS

A diet with a higher proportion of protein from plant sources is associated with lower mortality in those with eGFR<60mL/min/1.73m(2). Future studies are warranted to determine the causal role of plant protein intake in reducing mortality in those with eGFR<60mL/min/1.73m(2).

Comparison of high vs. normal/low protein diets on renal function in subjects without chronic kidney disease: a systematic review and meta-analysis

BACKGROUND

It was the aim of the present systematic review and meta-analysis to investigate the effects of high protein (HP) versus normal/low protein (LP/NP) diets on parameters of renal function in subjects without chronic kidney disease.

METHODS

Queries of literature were performed using the electronic databases MEDLINE, EMBASE, and the Cochrane Trial Register until 27th February 2014. Study specific weighted mean differences (MD) were pooled using a random effect model by the Cochrane software package Review Manager 5.1.

FINDINGS

30 studies including 2160 subjects met the objectives and were included in the meta-analyses. HP regimens resulted in a significantly more pronounced increase in glomerular filtration rate [MD: 7.18 ml/min/1.73 m2, 95% CI 4.45 to 9.91, p<0.001], serum urea [MD: 1.75 mmol/l, 95% CI 1.13 to 237, p<0.001], and urinary calcium excretion [MD: 25.43 mg/24h, 95% CI 13.62 to 37.24, p<0.001] when compared to the respective LP/NP protocol.

CONCLUSION

HP diets were associated with increased GFR, serum urea, urinary calcium excretion, and serum concentrations of uric acid. In the light of the high risk of kidney disease among obese, weight reduction programs recommending HP diets especially from animal sources should be handled with caution.

Effects of high-protein versus high-carbohydrate diets on markers of β-cell function, oxidative stress, lipid peroxidation, proinflammatory cytokines, and adipokines in obese, premenopausal women without diabetes: a randomized controlled trial

OBJECTIVE

To study the effects of high-protein versus high-carbohydrate diets on various metabolic end points (glucoregulation, oxidative stress [dichlorofluorescein], lipid peroxidation [malondialdehyde], proinflammatory cytokines [tumor necrosis factor-α and interleukin-6], adipokines, and resting energy expenditure [REE]) with high protein-low carbohydrate (HP) and high carbohydrate-low protein (HC) diets at baseline and after 6 months of dietary intervention.

RESEARCH DESIGN AND METHODS

We recruited obese, premenopausal women aged 20-50 years with no diabetes or prediabetes who were randomized to HC (55% carbohydrates, 30% fat, and 15% protein) or HP (40% carbohydrates, 30% fat, and 30% protein) diets for 6 months. The diets were provided in prepackaged food, which provided 500 kcal restrictions per day. The above metabolic end points were measured with HP and HC diet at baseline and after 6 months of dietary intervention.

RESULTS

After 6 months of the HP versus HC diet (12 in each group), the following changes were significantly different by Wilcoxon rank sum test for the following parameters: dichlorofluorescein (-0.8 vs. -0.3 µmol/L, P < 0.0001), malondialdehyde (-0.4 vs. -0.2 μmol/L, P = 0.0004), C-reactive protein (-2.1 vs. -0.8 mg/L, P = 0.0003), E-selectin (-8.6 vs. -3.7 ng/mL, P = 0.0007), adiponectin (1,284 vs. 504 ng/mL, P = 0.0011), tumor necrosis factor-α (-1.8 vs. -0.9 pg/mL, P < 0.0001), IL-6 (-1.3 vs. -0.4 pg/mL, P < 0.0001), free fatty acid (-0.12 vs. 0.16 mmol/L, P = 0.0002), REE (259 vs. 26 kcal, P < 0.0001), insulin sensitivity (4 vs. 0.9, P < 0.0001), and β-cell function (7.4 vs. 2.1, P < 0.0001).

CONCLUSIONS

To our knowledge, this is the first report on the significant advantages of a 6-month hypocaloric HP diet versus hypocaloric HC diet on markers of β-cell function, oxidative stress, lipid peroxidation, proinflammatory cytokines, and adipokines in normal, obese females without diabetes.

The role of high-protein diets in body weight management and health

Studies examining the health benefits of high-protein diets typical of most affluent and many developing countries are not consistent. Prospective epidemiological studies relating dietary protein to clinical and metabolic endpoints suggest increased weight gain and increased risk of diabetes amongst those with a high protein intake and an increased risk of cancer with high intakes of red meat, but lower blood pressure and possibly a reduced risk of heart disease with higher protein intakes. The potential for high-protein diets to confer greater benefit than other diets has been examined using ad libitum and energy restricted diets. Of greatest interest have been the comparisons between high-protein and high-carbohydrate diets. Many trials have reported greater weight loss especially in the context of ad libitum diets over the short-to medium-term, sparing of lean body mass, lowering of triglyceride levels, improved HDL: total cholesterol ratio and improved glycaemic control. Limited data regarding insulin sensitivity are less consistent. A major difficulty in interpreting the results of these studies is that carbohydrate quality has not been taken into account. Furthermore, longer term comparisons of weight reducing diets differing in macronutrient composition have reported similar outcomes, suggesting that compliance is a more important consideration. Nevertheless dietary patterns with high-protein intakes are appropriate for weight reduction and weight maintenance and may be useful for those who have high triglyceride levels and other features of the metabolic syndrome.

Safety and efficacy of high-protein diets for weight loss

Dietary strategies that can help reduce hunger and promote fullness are beneficial for weight control, since these are major limiting factors for success. High-protein (HP) diets, specifically those that maintain the absolute number of grams ingested, while reducing energy, are a popular strategy for weight loss (WL) due to the effects of protein-induced satiety to control hunger. Nonetheless, both the safety and efficacy of HP WL diets have been questioned, particularly in combination with low-carbohydrate advice. Nonetheless, for short-to-medium-term intervention studies (over several months), increasing the energetic contribution of protein does appear effective. The effects of HP diets on appetite, bone health, renal function, blood pressure, cardiovascular bio-markers, antioxidant status, gut health and psychological function are discussed. Further research is warranted to validate the physiological effects of HP diets over longer periods of time, including studies that modify the quality of macronutrients (i.e. the type of carbohydrate, fat and protein) and the interaction with other interventions (e.g. exercise and dietary supplements).

Plant and animal protein intake and its association with overweight and obesity among the Belgian population

The objective of the present study was to assess animal and plant protein intakes in the Belgian population and to examine their relationship with overweight and obesity (OB). The subjects participated in the Belgian National Food Consumption Survey conducted in 2004. Food consumption was assessed by using two non-consecutive 24 h dietary recalls. About 3083 participants ( ≥ 15 years of age; 1546 males, 1537 females) provided completed dietary information. Animal protein intake (47 g/d) contributed more to total protein intakes of 72 g/d than plant protein intake, which accounted for 25 g/d. Meat and meat products were the main contributors to total animal protein intakes (53 %), whereas cereals and cereal products contributed most to plant protein intake (54 %). Males had higher animal and plant protein intakes than females (P < 0·001). Legume and soya protein intakes were low in the whole population (0·101 and 0·174 g/d, respectively). In males, animal protein intake was positively associated with BMI (β = 0·013; P = 0·001) and waist circumference (WC; β = 0·041; P = 0·002). Both in males and females, plant protein intake was inversely associated with BMI (males: β = − 0·036; P < 0·001; females: β = − 0·046; P = 0·001) and WC (male: β = − 0·137; P < 0·001; female: β = − 0·096; P = 0·024). In conclusion, plant protein intakes were lower than animal protein intakes among a representative sample of the Belgian population and decreased with age. Associations with anthropometric data indicated that plant proteins could offer a protective effect in the prevention of overweight and OB in the Belgian population.

Supplemental barley protein and casein similarly affect serum lipids in hypercholesterolemic women and men

High-protein diets have been advocated for weight loss and the treatment of diabetes. Yet animal protein sources are often high in saturated fat and cholesterol. Vegetable protein sources, by contrast, are low in saturated fat and without associated cholesterol. We have therefore assessed the effect on serum lipids of raising the protein intake by 5% using a cereal protein, barley protein, as part of a standard therapeutic diet. Twenty-three hypercholesterolemic men and postmenopausal women completed a randomized crossover study comparing a bread enriched with either barley protein or calcium caseinate [30 g protein, 8374 kJ (2000 kcal)] taken separately as two 1-mo treatment phases with a minimum 2-wk washout. Body weight and diet history were collected weekly during each treatment. Fasting blood samples were obtained at wk 0, 2, and 4. Palatability, satiety, and compliance were similar for both the barley protein- and casein-enriched breads, with no differences between the treatments in effects on serum LDL cholesterol or C-reactive protein, measures of oxidative stress, or blood pressure. Nevertheless, because no adverse effects were observed on cardiovascular risk factors, barley protein remains an additional option for raising the protein content of the diet.

Continuous therapy with transdermal nitroglycerin does not affect biomarkers of vascular inflammation and injury in healthy volunteers

Continuous exposure to nitroglycerin (GTN) results in development of tolerance and is associated with increased free radical production and abnormal endothelial function. Elevated plasma biomarkers of inflammation have been shown to be associated with endothelial dysfunction in most cardiovascular conditions. It remains unclear whether exposure to GTN is also associated with increased biomarkers of endothelial and vascular injury or vascular inflammation. In an investigator-blind study, a total of 28 healthy volunteers were randomized to continuous therapy with GTN (0.6 mg/h 24 h/day for 7 days) or no therapy. Venous blood was collected on day 0 and day 7. Plasma levels of markers such as asymmetric dimethyl-arginine (ADMA), human soluble P-selectin, interleukin-6, tumor necrosis factor-alpha, intercellular adhesion molecule-1, and oxidized low-density lipoproteins were measured. The levels of blood markers on day 0 were similar in the control and GTN-treated groups. After 7 days of GTN exposure, there were no significant changes in the different markers of vascular inflammation and injury either in the GTN or control group (all p > 0.5). The present study documents that prolonged continuous therapy with transdermal GTN therapy is not associated with changes in markers of vascular inflammation and injury.

Vegetarian and vegan diets in type 2 diabetes management

Vegetarian and vegan diets offer significant benefits for diabetes management. In observational studies, individuals following vegetarian diets are about half as likely to develop diabetes, compared with non-vegetarians. In clinical trials in individuals with type 2 diabetes, low-fat vegan diets improve glycemic control to a greater extent than conventional diabetes diets. Although this effect is primarily attributable to greater weight loss, evidence also suggests that reduced intake of saturated fats and high-glycemic-index foods, increased intake of dietary fiber and vegetable protein, reduced intramyocellular lipid concentrations, and decreased iron stores mediate the influence of plant-based diets on glycemia. Vegetarian and vegan diets also improve plasma lipid concentrations and have been shown to reverse atherosclerosis progression. In clinical studies, the reported acceptability of vegetarian and vegan diets is comparable to other therapeutic regimens. The presently available literature indicates that vegetarian and vegan diets present potential advantages for the management of type 2 diabetes.

Attenuation of diabetic complications by C-phycoerythrin in rats: antioxidant activity of C-phycoerythrin including copper-induced lipoprotein and serum oxidation

In the present study, the protective role of purified C-phycoerythrin (C-PE) against diabetic complications and Cu-mediated lipoprotein oxidation was evaluated. C-PE (25 and 50 mg/kg body weight per d) was administered to experimental streptozotocin-nicotinamide-induced type 2 diabetic male rats for 28 d. C-PE treatment successfully ameliorated diabetic complications by decreasing food intake, organ weights, serum concentrations of glucose, cholesterol, TAG, VLDL-cholesterol, creatinine, uric acid and thiobarbituric acid-reactive substances (TBARS), with increases in body weight, Hb, total protein, bilirubin and ferric-reducing ability of plasma values. Hepatic and renal tissues demonstrated significant decreases in TBARS, lipid hydroperoxide and conjugated diene contents, with increases in superoxide dismutase, catalase, glutathione peroxidase, reduced glutathione, vitamin E and vitamin C levels. Furthermore, the 4-week ex vivo and in vitro administration of C-PE (0.5 and 1.0 mg/ml) indicated a decrease in Cu-mediated serum oxidation. The kinetics of the LDL oxidation profile showed significant prolongation of the lag phase with declines in oxidation rate, conjugated dienes, lipid hydroperoxide and TBARS. Results indicated the involvement of C-PE in the amelioration of diabetic complications by significant reductions in oxidative stress and oxidised LDL-triggered atherogenesis.

Metabolic effects of high-protein diets

Protein is more satiating than carbohydrate or fat, and high-protein diets (25%-35% of energy) are commonly used for weight loss. High-protein diets usually replace carbohydrate with protein and may be low or high in saturated fat. Invariably, serum triglyceride is lower with the lower intake of carbohydrate, but the effects on high-density lipoprotein cholesterol and low-density lipoprotein cholesterol are strongly dependent on the amount of carbohydrate restriction and the intake of saturated fat, and in some cases low-density lipoprotein cholesterol may rise despite weight loss. In situations of weight stability, higher intakes of protein are associated with lower blood pressures, and in diabetic patients higher intakes of protein are associated with lower glycosylated hemoglobin. The overall effect on long-term atherosclerosis risk is not clear, as the current limited epidemiology provides conflicting data.