Oxidative stress is bad because it can damage DNA and this is a way into cell transformation and cancer, and because antioxidants can protect cells from oxidative stress, they are good for people with cancer, right? Well, not exactly.
A recent study published in Nature showed that mice injected with cancer cells and treated with antioxidants produced a lot more tumors than the ones with no antioxidants.
The researchers discovered that oxidative stress is dangerous not only for healthy cells, but for metastatic ones too. That is why cancer cells usually have metabolic changes during metastasis that increases their capacity to resist oxidative stress. At this point, adding some antioxidants can help this cells resist the journey inside blood vessels and distant organs that are rich in reactive oxygen species (ROS), the agents of oxidative stress.
The conclusion of the paper shows us that the role of the antioxidants is not completely understood:
ROS can cause oncogenic mutations and activate oncogenic pathways, raising the possibility that treatment with antioxidants could suppress the initiation or progression of some cancers. Antioxidants or antioxidant enzymes suppress cancer initiation in some contexts while increasing cancer initiation in other contexts. Increasing dietary antioxidants has generally not reduced cancer incidence in clinical trials. Dietary supplementation with antioxidants actually increased incidence and death from lung and prostate cancer. Dietary supplementation with folate promotes the development and progression of breast cancer. Our results suggest that antioxidants promote disease progression, at least in melanoma, by promoting metastasis.
Of course more studies are needed, but maybe we should follow the advice from one of the researchers: “personally, from the results we’ve seen, I would avoid supplementing my diet with large amounts of antioxidants if I had cancer.”These are interesting resources about the topic:
Original article: Oxidative stress inhibits distant metastasis by human melanoma cells