Effects of the Mediterranean Diet on metabolic indices and quality of life in cancer patients: A systematic review and meta-analysis of randomized controlled trials

The Mediterranean diet (MD) had a protective effect on cancer prevention. However, there has not been a systematic evaluation of the diet's comprehensive effects on metabolic indices and quality of life in cancer patients. The present meta-analysis summarizes for the first time the effects of MD on metabolic indices and quality of life in cancer patients. We conducted a randomized controlled trial (RCT) search on PubMed, Embase, and Cochrane Library, which recruited cancer patients receiving the MD intervention. In this meta-analysis, nine RCTs were included. Two authors independently extracted the data and checked the accuracy of the results. Compared with the control group, MD reduced the body weight (p < 0.00001), fat mass (p < 0.00001), % fat mass (p = 0.02), waist circumference (p < 0.00001), and BMI (p < 0.0001) of cancer patients. MD improved the scores of FICT-G (p = 0.002), Physical well-being (p < 0.00001), Emotional well-being (p < 0.00001), Functional well-being (p = 0.0002), and Fatigue (p < 0.00001). MD also increased the serum vitamin C level. Sensitivity analysis revealed that MD reduced the levels of blood glucose (p < 0.00001), triglyceride (p = 0.003), total cholesterol (p = 0.009), and LDH-C (p = 0.0002) in cancer patients. However, it did not affect the levels of HDL-C (p = 0.63) and vitamin A (p = 0.97). In brief, our findings indicate that higher MD compliance can reduce the weight and fat mass of cancer patients, improve their quality of life, and alleviate fatigue. Furthermore, MD can potentially improve cancer patients' serum glucose and lipid metabolism and enhance the body's antioxidant stress capacity. Nevertheless, further high-quality randomized controlled trials with larger sample sizes are necessary to obtain more dependable outcomes. INPLASY registration number: INPLASY 202320006.