Effect of Ketogenic Diets on Cardio-Metabolic Outcomes in Cancer Patients: A Systematic Review and Meta-Analysis of Controlled Clinical Trials

Evaluating the effects of dietary patterns on circulating C-reactive protein levels in the general adult population: an umbrella review of meta-analyses of interventional and observational studies

Adopting a healthy dietary pattern may be an initial step in combating inflammation-related chronic diseases; however, a comprehensive synthesis evaluating current evidence is lacking. This umbrella review aimed to summarise the current evidence on the effects of dietary patterns on circulating C-reactive protein (CRP) levels in adults. We conducted an exhaustive search of the Pubmed, Scopus and Epistemonikos databases, spanning from their inception to November 2023, to identify systematic reviews and meta-analyses across all study designs. Subsequently, we employed a random-effects model to recompute the pooled mean difference. Methodological quality was assessed using the A Measurement Tool to Assess Systematic Reviews 2 (AMSTAR 2) checklist, and evidence certainty was categorised as non-significant, weak, suggestive, highly suggestive or convincing (PROSPERO: CRD42023484917). We included twenty-seven articles with thirty meta-analyses of seven dietary patterns, fifteen of which (50 %) exhibited high methodological quality. The summary effects of randomised controlled trials (RCT) found that the Mediterranean diet was the most effective in reducing circulating CRP levels, followed by Vegetarian/Vegan and Energy-restricted diets, though the evidence was of weak quality. In contrast, Intermittent Fasting, Ketogenic, Nordic and Paleolithic diets did not show an inverse correlation with circulating CRP levels. Some results from combined interventional and observational studies, as well as solely observational studies, also agreed with these findings. These dietary patterns show the potential in reducing CRP levels in adults, yet the lack of high-quality evidence suggests future studies may alter the summary estimates. Therefore, further well-conducted studies are warranted.

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.

Diabetes Risk Reduction Diet (DRRD) and Breast Cancer Risk: A Review

BACKGROUND

Considering the significant involvement of insulin resistance in various forms of cancer, it is postulated that the implementation of a diabetic diet, which effectively mitigates insulin resistance, may potentially decrease the susceptibility to breast cancer among female individuals.

METHODS

In this literature review, a comprehensive electronic search of different databases was done using the keywords "Breast cancer" OR "breast tumor" OR "Breast Neoplasms" AND "diet" OR "diabetic diet" OR "Low Carbohydrate Diet" OR "Carbohydrate restricted diet" OR "High-Protein Low-Carbohydrate Diet" OR "diabetes risk reduction diet" OR "DRRD" as the main keywords.

RESULTS

Research has shown that the DRRD score is inversely correlated with breast cancer risk. In fact, for every three-point increase in the DRRD score, the risk of breast cancer decreases by 7%. Studies have shown that higher DRRD scores in breast cancer patients are associated with a reduced risk of cancer and a higher chance of survival.

CONCLUSION

The results of this study indicate a positive correlation between a higher level of adherence to the diabetes risk reduction diet (DRRD) and improved survival rates. This suggests that breast cancer survivors may benefit from making dietary modifications in line with a diabetic diet following their diagnosis.

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.

The Ketogenic Diet and Cardiovascular Diseases

The most common and increasing causes of death worldwide are cardiovascular diseases (CVD). Taking into account the fact that diet is a key factor, it is worth exploring this aspect of CVD prevention and therapy. The aim of this article is to assess the potential of the ketogenic diet in the prevention and treatment of CVD. The article is a comprehensive, meticulous analysis of the literature in this area, taking into account the most recent studies currently available. The ketogenic diet has been shown to have a multifaceted effect on the prevention and treatment of CVD. Among other aspects, it has a beneficial effect on the blood lipid profile, even compared to other diets. It shows strong anti-inflammatory and cardioprotective potential, which is due, among other factors, to the anti-inflammatory properties of the state of ketosis, the elimination of simple sugars, the restriction of total carbohydrates and the supply of omega-3 fatty acids. In addition, ketone bodies provide "rescue fuel" for the diseased heart by affecting its metabolism. They also have a beneficial effect on the function of the vascular endothelium, including improving its function and inhibiting premature ageing. The ketogenic diet has a beneficial effect on blood pressure and other CVD risk factors through, among other aspects, weight loss. The evidence cited is often superior to that for standard diets, making it likely that the ketogenic diet shows advantages over other dietary models in the prevention and treatment of cardiovascular diseases. There is a legitimate need for further research in this area.