Abstract Introduction: Extra virgin olive oil is a basic component of the Mediterranean diet; it contains several molecules with antioxidant, anti-inflammatory, anti-angiogenic and pro-apoptotic properties against a variety of cancers and influencing cellular metabolism too. Olive mill waste water (OMWW), a liquid residue produced in vast amounts during olive oil extraction, represents an environmental issue but on the other side it is a rich source of phytochemicals with potential health benefits. Particularly, OMWWs are rich in different phenolic compounds, that show promise in preventing the development of several disease disorders, including cancer. We have assessed the anti-angiogenic and anti-tumor properties exerted by a nutraceutical from purified OMWW extract, in in vitro and in vivo models, and evaluated its effect in a human pilot study upon informed consent. Experimental procedures: OMWWs ability to affect cell proliferation and survival on different cancer cell lines was assessed by MTT. OMWWs interference with human umbilical endothelial vein cells (HUVECs) tube formation, migration and invasive capacities was studied by endothelial cell morphogenesis and migration assays. The inhibition of angiogenesis and tumor cell growth was investigated by the matrigel assay and tumour xenograft. To evaluate contribution of potential metabolomic biomarkers, SANIST (surface-activated chemical ionization-electrospray-NIST technology) mass spectrometric data-based platform has been employed on sera from a pilot study (Aiello et al, in preparation). Results: OMWW extract shown a potent inhibitory effect inhibiting cells proliferation of both cancer cell lines and HUVECs.OMWW inhibited several molecular targets expression, including IL8, Angiogenin, mTOR, VEGF, CXCR4, CXCL12 and CXCL8, in tumor cells and in TNF-α-stimulated HUVEC. We nalyzed sera from volunteers, after nutraceutical intervention with Oliphenoliaand we assessed several biological parameters. Endogenous vitamin D was significantly increased, as well as albumin, direct bilirubin, and calcium. We also observed glycemia and potassium decrease after Oliphenolia assumption. A previously unknow form of Vitamin D was also detected by mass spectrometry. Conclusions: OMWW extract has shown a stronger anti-angiogenic and anti-tumor properties, with potential chemo-preventive potentials. Results of human pilot study shows Oliphenolia as a promising and interesting natural dietary supplement, rich in polyphenol compounds, that can exert anti-inflammatory and antioxidant activities. Acknowledgements: This study was supported by a donation from the Fattoria La Vialla di Gianni, Antonio e Bandino Lo Franco - SAS (Arezzo, Italy). We are grateful to Professor Anna Aiello, and Professor Calogero Caruso, Palermo University for the pilot study. Citation Format: Adriana Albini, Luana Calabrone, Francesca Albini, Paola Corradino, Simone Cristoni, Douglas M. Noonan. A nutraceutical supplement derived from olive oil byproducts exhibits potential cancer preventive properties in preclinical studies and increases vitamin D levels [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7298.