What Is the Role of Nutraceutical Products in Cancer Patients? A Systematic Review of Randomized Clinical Trials

Chemotherapy represents the main pharmacological cancer treatment. Recently, positive effects emerged with the combination of anticancer therapy and nutraceutical products. The aim of this systematic review is to collect and synthesize the available scientific evidence regarding the potential effects of nutraceuticals on cancer cells. A systematic literature search of randomized clinical trials of nutraceutical products in patients with cancer published up to 15 December 2022 was conducted using three data sources: Embase, PubMed, and Web of Science. The effect of high-dose isoflavone supplements on prostate cancer resulted in stabilization or reduction of PSA concentrations in 50% of isoflavone group patients six months after treatment. High doses of vitamin D supplementation plus chemotherapy in patients with advanced or metastatic colorectal cancer showed a median PFS of 13.0 months (95% CI, 10.1–14.7 months) for 49 patients. The effect of vitamin D supplementation on markers of inflammatory level and antioxidant capacity in women with breast cancer showed a significant increase in serum vitamin D concentration (28 ± 2.6 to 39 ± 3.5; p = 0.004) after 8 weeks of treatment. In conclusion, nutraceutical supplements represent a potentially growing sector and can be utilized in medical treatment or nutrition to provide integrated medical care.