Experts at the University of Rochester found that the antioxidant, resveratrol, disturbs the function of mitochondria, the energy source within cells.
Their findings, which were achieved using pancreatic cells in a laboratory environment, are published in the journal Advances in Experimental Medicine and Biology.
The researchers also found that, by treating cancer cells with resveratrol and then using radiation treatment, they were able to induce a natural process of cell death called apoptosis.
Lead author Dr Paul Okunieff, head of radiation oncology at the university's James P Wilmot Cancer Centre, said that the research could have many implications for patients.
Dr Okunieff said that antioxidant research is "very active and very seductive right now".
He added: "Resveratrol seems to have a therapeutic gain by making tumour cells more sensitive to radiation and making normal tissue less sensitive."