Effect of Ketogenic Diets on Body Composition and Metabolic Parameters of Cancer Patients: A Systematic Review and Meta-Analysis

Impact of the ketogenic diet as a dietary approach on cardiovascular disease risk factors: a meta-analysis of randomized clinical trials

BACKGROUND

Cardiovascular diseases (CVD) remain the leading cause of mortality globally, and the scarcity of scientific evidence regarding the impact of ketogenic diets on CVD risk factors necessitates urgent attention and redress.

OBJECTIVES

This meta-analysis evaluates the impact of the ketogenic diet on CVD risk factors compared with control diets through randomized controlled trials (RCTs).

METHODS

The study was registered in advance in the PROSPERO database (CRD42023491853). A systematic search was conducted across PubMed, Web of Science, EMBASE, and Cochrane Library to identify relevant RCTs. Fixed and random effects were employed to calculate the mean differences and 95% confidence intervals (CIs) for changes in CVD risk factors pre- and postketogenic diet intervention.

RESULTS

A total of 27 RCTs with 1278 participants were analyzed. The ketogenic diet intervention presented increase in total cholesterol (mean differences: 0.36 mmol/L; 95% CI: 0.15, 0.57; I2: 85.1%), low-density lipoprotein cholesterol (mean differences: 0.35 mmol/L; 95% CI: 0.20, 0.50; I2: 73.9%) and high-density lipoprotein cholesterol (mean differences: 0.16 mmol/L; 95% CI: 0.09, 0.23; I2: 86.7%) concentrations. Reductions were observed in the triglyceride (mean differences: -0.20 mmol/L; 95% CI: -0.29, -0.11; I2: 72.2%), blood glucose (mean differences: -0.18 mmol/L; 95% CI: -0.33, -0.02; I2: 76.4%), blood insulin (mean differences: -8.32 pmol/L; 95% CI: -14.52, -2.12; I2: 81.5%), diastolic blood pressure (mean differences: -1.41 mmHg; 95% CI: -2.57, -0.26; I2: 49.1%), weight (mean differences: -2.59 kg; 95% CI: -3.90, -1.28; I2: 87.4%), and body mass index (mean differences: -1.59 kg/m2; 95% CI: -2.32, -0.86; I2: 84.5%) concentrations after implementing ketogenic diets.

CONCLUSIONS

Although the ketogenic diet demonstrates benefits in terms of triglyceride, blood pressure, weight, and glycemic control, its impact on CVD risk factors, especially the elevated total cholesterol and low-density lipoprotein cholesterol concentrations, warrants a cautious approach.

Postoperative rehabilitation and quality of life evaluation for transoral endoscopic thyroidectomy vestibular approach

There are no targeted rehabilitation training modalities and assessment tools for patients after transoral endoscopic thyroidectomy vestibular approach (TOETVA). Herein, we develop a new assessment questionnaire and rehabilitation training modality and evaluate its safety and effectiveness. The THYCA-QoL-TOETVA questionnaire was compiled, and reliability and validity analyses were performed. Patients were divided into the new rehabilitation training group (N) or the conventional rehabilitation training group (C), and 1:1 propensity score matching (PSM) was performed after administering questionnaires to patients in both groups. Cervical range of motion (CROM) data were also measured and collected for statistical analysis. The questionnaire used in this study showed good expert authority, coordination, internal consistency, and questionnaire reliability. A total of 476 patients were included after PSM, and the questionnaire results showed that recovery and quality of life were better in the N group than in the C group (124.55 ± 8.171 vs. 122.94 ± 8.366, p = 0.026). Analysis of cervical spine mobility showed that rehabilitation was better in the N group compared to the C group at postoperative one month (flexion: 1.762°, extension: 4.720°, left lateral bending: 3.912°, right lateral bending: 4.061°, left axial rotation: 5.180°, right axial rotation: 5.199°, p value all of these < 0.001), and at postoperative three months (flexion: 2.866°, extension: 2.904°, left lateral bending: 3.927°, right lateral bending: 3.330°, left axial rotation: 4.395°, right axial rotation: 3.992°, p value all of these < 0.001). The THYCA-QoL-TOETVA provides an appropriate and effective tool for measuring the postoperative quality of life of TOETVA patients. This new rehabilitation training can effectively alleviate the problem of limited neck movement and improve the quality of life of patients after TOETVA surgery.Trial registration: ChiCTR2300069097.

Effects of ketogenic diets on cancer-related variables: A systematic review and meta-analysis of randomised controlled trials

Cancer is a global health concern influenced by genetics, environment and lifestyle choices. Recent research shows that a ketogenic diet (KD) might ease cancer symptoms and reduce tumour size. We hypothesised that the KD could result in improvements in cancer-related variables. Therefore, this study aims to perform a systematic review and meta-analysis to assess the KD's efficacy for patients with cancer. The databases PubMed (MEDLINE), Web of Science, CINAHL and Open Grey were utilised for conducting a systematic review and meta-analysis. The analysis was limited to randomised controlled trials with adult participants aged 18 years and above. Levels of glucose, cholesterol, insulin-like growth factor 1, weight and quality of life were evaluated following the KD. After identifying 596 articles in the initial search, eight studies, lasting between 4 and 16 weeks, were included in the systematic review and seven in the meta-analysis. The KD led to decreased glucose levels in patients with cancer but did not show significant improvements in cholesterol, insulin-like growth factor 1, weight or quality of life. Based on the results of this systematic review and meta-analysis, there is insufficient evidence to establish a definitive link between the KD and cancer-related parameters. While some studies suggest potential benefits in terms of some outcomes and tumour size reduction, further research is required to fully comprehend the effects of this diet.

Emerging Pathophysiological Roles of Ketone Bodies

The discovery of insulin approximately a century ago greatly improved the management of diabetes, including many of its life-threatening acute complications like ketoacidosis. This breakthrough saved many lives and extended the healthy lifespan of many patients with diabetes. However, there is still a negative perception of ketone bodies stemming from ketoacidosis. Originally, ketone bodies were thought of as a vital source of energy during fasting and exercise. Furthermore, in recent years, research on calorie restriction and its potential impact on extending healthy lifespans, as well as studies on ketone bodies, have gradually led to a reevaluation of the significance of ketone bodies in promoting longevity. Thus, in this review, we discuss the emerging and hidden roles of ketone bodies in various organs, including the heart, kidneys, skeletal muscles, and brain, as well as their potential impact on malignancies and lifespan.

Skeletal muscle and visceral adipose radiodensities are pre-surgical, non-invasive markers of aggressive kidney cancer

INTRODUCTION

Most studies on body composition in kidney cancer have been conducted among patients with metastatic disease. Given that aggressive tumours can adversely impact body composition and even non-metastatic tumours can be aggressive, we evaluated associations between pre-surgical body composition features and tumour pathological features in patients with non-metastatic clear cell renal cell cancer (ccRCC).

METHODS

The Resolve Cohort consists of 1239 patients with non-metastatic ccRCC who underwent nephrectomy at Memorial Sloan Kettering Cancer Center between 2000 and 2020. The cross-sectional areas and radiodensities of skeletal muscle, visceral adipose, and subcutaneous adipose tissues were determined from pre-surgical computed tomography (CT) scans at the third lumbar vertebrae using Automatica software. Pearson's correlation coefficients describe inter-relationships among BMI and body composition variables, while odds ratios (OR) and 95% confidence intervals (CI) estimate associations between continuous body composition features (per 1-standard deviation) and advanced stage (Stage III vs. Stages I-II) and high Fuhrman grade (Grades 3-4 vs. 1-2) from multivariable logistic regression models that considered the potential impact of biological sex, contrast enhanced CTs, and early age at onset of ccRCC.

RESULTS

The cohort was predominantly male (69%), white (89%), and had a median age of 58. The proportion of patients presenting with advanced stage and high-grade disease were 31% and 51%, respectively. In models that adjusted for demographics and all body composition variables simultaneously, decreasing skeletal muscle radiodensity (i.e., more fat infiltration) but increasing visceral adipose tissue radiodensity (i.e., more lipid depletion) were associated with advanced tumour features. Per 8.4 HU decrease in skeletal muscle radiodensity, the odds of presenting with advanced stage was 1.61 (95% CI: 1.34-1.93). Per 7.22 HU increase in visceral adipose tissue radiodensity, the odds of presenting with advanced stage was 1.45 (95% CI: 1.22-1.74). Skeletal muscle index (i.e., sarcopenia) was not associated with either tumour feature. Similar associations were observed for Fuhrman grade, a more direct marker of tumour aggressiveness. Associations did not differ by sex, contrast use, or age at onset of ccRCC.

CONCLUSIONS

Lipid infiltrated skeletal muscle, but lipid depleted visceral adipose tissue were independently associated with advanced tumour features in non-metastatic ccRCC. Findings highlight the importance of evaluating the full range of body composition features simultaneously in multivariable models. Interpreting pre-surgical CTs for body composition for patients may be a novel and non-invasive way to identify patients with aggressive renal tumours, which is clinically relevant as renal biopsies are not routinely performed.

Effects of ketogenic diet on weight loss parameters among obese or overweight patients with polycystic ovary syndrome: a systematic review and meta-analysis of randomized controlled trails

Aim

To evaluate how effective a low carbohydrate ketogenic diet (KD) is for changing key physical measurements such as weight, waist circumference (WC), body mass index (BMI), and fat mass (FM) in women with polycystic ovary syndrome (PCOS) who were obese or overweight.

Methods

Several online databases, including PubMed, Scopus, EMBASE, Cochrane Library, and Web of Science (WOS), were searched systematically to find relevant randomized controlled trials (RCTs) up until June 2023. The Q-test and I2 statistics were used to assess the level of heterogeneity among the included studies. The data were then combined using either a fixed or random effects model and presented as a weighted mean difference (WMD) along with a 95% confidence interval (CI).

Results

Of the 682 citations, 11 RCTs were included. The pooled results showed a significant decrease in the WMD of weight levels [WMD = -9.13 kg; 95% CI, -11.88, -6.39, P < 0.001; I2 = 87.23%] following KD. Moreover, KD significantly reduced BMI levels [WMD = -2.93 kg/m2; 95% CI, -3.65, -2.21, P < 0.001; I2 = 78.81%] compared to the controls. Patients with PCOS received KD demonstrated significant decrease in WC [WMD = -7.62 cm; 95% CI, -10.73, -4.50, P < 0.001; I2 = 89.17%] and FM [WMD = -5.32 kg; 95% CI, -7.29, -3.36, P < 0.001; I2 = 83.97%].

Conclusion

KD was associated with lower weight loss (WL) parameters, including weight, BMI, WC, and FM, in obese or overweight women with PCOS, highlighting the significance of physicians and nurses in taking care of the nutritional needs of overweight/obese patients with PCOS.

Natural products and dietary interventions on liver enzymes: an umbrella review and evidence map

Background

The association between natural products and dietary interventions on liver enzymes is unclear; therefore, this study aimed to examine their effects on liver enzymes in adults.

Methods

PubMed, Embase, and Cochrane Library of Systematic Reviews databases were searched from inception until March 2023. The Assessment of Multiple Systematic Reviews-2 (AMSTAR-2) and Grading of Recommendations Assessment, Development, and Evaluation (GRADE) systems were used to assess the methodological and evidence quality, and the therapeutic effects were summarized in a narrative form.

Results

A total of 40 meta-analyses on natural products (n = 25), dietary supplements (n = 10), and dietary patterns (n = 5) were evaluated, and results were presented in a narrative form. The overall methodological quality of the included studies was relatively poor. The results indicated that positive effects were observed for nigella sativa, garlic, artichoke, curcumin, silymarin, vitamin E, vitamin D, L-carnitine, propolis, and polyunsaturated fatty acids on certain liver enzymes. The dietary patterns, including high-protein, Mediterranean, and calorie-restriction diets and evening snacks, may reduce liver enzymes; however, other supplements and herbs did not reduce liver enzyme levels or have minimal effects. The evidence quality was generally weak given the risk of bias, heterogeneity, and imprecision.

Conclusion

This umbrella review suggests that natural products and dietary interventions have beneficial therapeutic effects on liver enzymes levels. Further clinical trials are necessary to establish the effectiveness of supplements that reduce liver enzymes.

Anti-tumor effects of ketogenic diets and their synergism with other treatments in mice: Bayesian evidence synthesis of 1755 individual mouse survival data

BACKGROUND

Ketogenic diets (KDs) are high-fat diets with putative anti-tumor effects. The aim of this study was to synthesize the evidence for the anti-tumor effects of KDs in mice, with a focus on their possible synergism with chemotherapy (CT), radiotherapy (RT), or targeted therapies (TT).

METHODS

Relevant studies were retrieved from a literature search. A total of 43 articles reporting on 65 mouse experiments fulfilled the inclusion criteria, and 1755 individual mouse survival times were collated from the study authors or the publications. The restricted mean survival time ratio (RMSTR) between the KD and control groups served as the effect size. Bayesian evidence synthesis models were used to estimate pooled effect sizes and to assess the impact of putative confounders and synergism between KD and other therapies.

RESULTS

Overall, there was a significant survival-prolonging effect of KD monotherapy (RMSTR = 1.161 ± 0.040), which was confirmed in meta-regression accounting for syngeneic versus xenogeneic models, early versus late KD start and subcutaneous versus other organ growth. Combining the KD with RT or TT, but not CT, was associated with a further 30% (RT) or 21% (TT) prolongation of survival. An analysis accounting for 15 individual tumor entities showed that KDs exerted significant survival-prolonging effects in pancreatic cancer (all treatment combinations), gliomas (KD + RT and KD + TT), head and neck cancer (KD + RT), and stomach cancer (KD+RT and KD + TT).

CONCLUSIONS

This analytical study confirmed the overall anti-tumor effects of KDs in a large number of mouse experiments and provides evidence for synergistic effects with RT and TT.

Methodological Challenges and Confounders in Research on the Effects of Ketogenic Diets: A Literature Review of Meta-Analyses

Several meta-analyses have found a positive association between a popular type of "fad diet", ketogenic diets, and their effect on anthropometric and blood parameters. However, the non-specific inclusion criteria for meta-analyses may lead to incorrect conclusions. The aim of this literature review is to highlight the main confounders and methodological pitfalls of meta-analyses on ketogenic diets by inspecting the presence of key inclusion criteria. The PubMed, Embase, and Web of Science databases and the Cochrane Database of Systematic Reviews were searched for meta-analyses. Most meta-analyses did not define the essential parameters of a ketogenic diet (i.e., calories, macronutrient ratio, types of fatty acids, ketone bodies, etc.) as inclusion criteria. Of the 28 included meta-analyses, few addressed collecting real, re-measured nutritional data from the ketogenic diet and control groups in parallel with the pre-designed nutritional data. Most meta-analyses reported positive results in favor of ketogenic diets, which can result in erroneous conclusions considering the numerous methodological pitfalls and confounders. Well-designed clinical trials with comparable results and their meta-analyses are needed. Until then, medical professionals should not recommend ketogenic diets as a form of weight loss when other well-known dietary options have been shown to be healthy and effective.

Obesity control and liver health in breast cancer: Normalized hepatic elasticity after ketogenic diet

Most socially significant diseases, including breast cancer, are undeniably linked to obesity. Recently, a positive relationship between excessive weight and increased risk of breast cancer poor outcomes has been proved. Liver integrity is an essential point during chemotherapy. Consequently, a hepatic safe therapeutic approach for managing obesity in patients with breast cancer should be initiated. Our study aimed to assess the impact of the ketogenic diet on body mass index (BMI) and to evaluate its safety on liver function in female patients with breast cancer. The study comprised 520 women with ductal breast cancer who underwent a 60-day modified ketogenic diet. BMI, prothrombin time (PT), activated partial thromboplastin clotting time (aPTT), aspartate aminotransferase to platelet ratio index (APRI), and ultrasound liver elasticity was evaluated before and after the diet. The results showed a significant decrease in BMI and an improvement in ultrasound liver elasticity in all the participants after completing the diet. Before the KD, the participants' median BMI was 35.0 kg/m2, and after the 60-day diet, the median BMI was reduced to 30.0 kg/m2. No significant liver parameter changes were found after the diet. In conclusion, we can safely promote the keto diet amongst individuals with an increased chance of developing breast cancer for a better disease prevention.

Keto Menu-Effect of Ketogenic Menu and Intermittent Fasting on the Biochemical Markers and Body Composition in a Physically Active Man-A Controlled Case Study

The combination of ketogenic diet (KD) with intermittent fasting (IF) has, for years, aroused a great interest in the scientific world and among healthy lifestyle enthusiasts. Its importance is even greater when the study subjects are physically active individuals. The aim of the study was a determination of the effect of strict calculated ketogenic menu combined with IF and with caloric deficit on the selected biochemical markers and body composition in a 23-year-old man performing strength training. At the same time, we decided to conduct the first so-deeply investigated and controlled case study in this respect. The study protocol included a 13-week-long ketogenic diet with intermittent fasting (of delayed time-restricted eating 16:8 type) and caloric deficit. A detailed menu was designed and was used by the man throughout the whole study duration. A number of blood tests were performed before and after the implemented dietary intervention. Additionally, body composition was determined weekly and the concentrations of glucose and ketone bodies, as well as pulse rate and arterial pressure, were measured daily. The most important changes noted included a significant increase in testosterone and vitamin D concentrations and significant reduction in the HOMA-IR index and concentrations of hepatic enzymes, insulin, glucose, iron, urea, and free triiodothyronine (FT3). Moreover, a significant improvement of body composition occurred (the ratio of total body mass to the adipose and muscular tissue and water mass improved). Favourable changes were also noted in heart rate and arterial pressure values. In view of that, the KD with IF and caloric deficit exerted favourable effects on most biochemical parameters and on body composition and caused an almost twofold increase in serum testosterone concentration.

Effects of very low carbohydrate ketogenic diets on skeletal health

PURPOSE OF REVIEW

Very low carbohydrate ketogenic diet (KD) therapy has been associated with skeletal demineralization in children with drug-resistant epilepsy, but the cause of this association is unclear. Recently, interest in the KD has grown owing to its potential benefits for other illnesses including cancer, type 2 diabetes, obesity, and polycystic kidney disease. Summaries of the best available evidence regarding effects of a KD on skeletal health are lacking.

RECENT FINDINGS

Recent rodent studies found that a KD can harm the growing skeleton, which corroborates most but not all studies in pediatric patients. Proposed mechanisms include chronic metabolic acidosis and depressed osteoanabolic hormones. Relative to other weight-reducing diets, a weight-reducing KD for treatment of obesity and/or type 2 diabetes in adults has not been associated with adverse skeletal effects. By contrast, recent evidence suggests that adaptation to a eucaloric KD may impair bone remodeling in elite adult athletes. Discrepancies in the literature may relate to differences between study populations and in diet formulation.

SUMMARY

Attention to skeletal health is warranted when using KD therapy given the uncertainty in the literature and suggestive harms in certain populations. Future research should focus on potential mechanisms of injury.