Antioxidants are compounds that have long been known to offer several health benefits, including protection against cancer; but a new study finds otherwise.

The study, published in the journal Nature last Wednesday, was conducted by researchers at the University of Texas Southwestern Medical Center and led by Sean Morrison.

Studying mice models, Morrison and colleagues found that antioxidants can make cancer cells spread rather quickly.

For the study, researchers transplanted melanoma cells to mice and either treated them with or without antioxidants to test how the compounds play a role in the spread of the cancer cells.

They found that in those mice that were given antioxidants, in this case N-acetylcysteine, cancer spread faster compared to the untreated group.

"We discovered that metastasizing melanoma cells experience very high levels of oxidative stress, which leads to the death of most metastasizing cells," Morrison said in a press release.

Giving antioxidants only led to the cancer cells to survive, supporting their growth and spread as a result.

Healthy individuals may continue to benefit from antioxidants as these compounds can help protect cells from damage brought by oxidative stress. With the latest findings, however, researchers also suggest that cancer patients receive pro-oxidants rather than antioxidants.

Although the experiment was only conducted on mice models, researchers believe that cancer patients may benefit well from pro-oxidants and that they should not include antioxidants in their diet.

Antioxidants were once strongly believed to be beneficial for cancer patients that several trials were conducted to study the compounds' role in the disease. Most of those trials produced mixed results.

Morrison also explained that people in those trials did not get any better and had their conditions worsened, that some of those trials had to be stopped.