Frustrating study warns antioxidant foods may fuel certain cancers

It's a popular trend to eat antioxidant-rich foods for their health-promoting effects. These polyphenols, flavonoids, and other plant compounds have been linked with a variety of benefits, including reducing blood pressure, helping control blood sugar, and even reducing the risk of developing cancer. A new study underscores the fact that nothing is perfect, however, warning that antioxidant-rich foods may fuel the development of one of the most common types of cancer.

The findings, which come from researchers with the Hebrew University of Jerusalem, are essentially unprecedented and help shed light on the role that both foods and gut bacteria play in human health and disease outcomes. The researchers investigated why the small intestines very rarely developers cancer, but the colon seems to be particularly prone to it — this variety of cancer is, in fact, one of the top killers of both men and women.

It turns out that gut bacteria, antioxidant-rich foods, and a gene called TP53 that is found in every cell all play a role in the development of colon cancer. TP53, the researchers explain, produces a protein called P53 that protects cells in its healthy form, but that can become damaged, turning the protein from being a protector into cancer fuel.

Gut bacteria, it turns out, plays a role in helping sustain this mutated P53 protein, allowing it to drive the formation and spread of cancerous tumors in the colon. However, when this same protein was introduced into the small intestines — which have very few gut bacteria — the body converted the mutated protein back into a healthy 'protector' protein.

The mutated protein wasn't able to fuel colon cancer, however, when the bacteria in the colon was first killed off using antibiotics, underscoring the role this flora plays in cancer. How do antioxidants tie into all of this? The otherwise beneficial gut bacteria produce antioxidant metabolites that appear to drive the mutated protein's cancer-proliferating effects.

In mice fed antioxidant-rich foods like black tea, nuts, chocolate, and berries, the gut bacteria was found to fuel mutated P53 proteins, paving the way for colon cancer. Talking about this, the university's Professor Yinon Ben-Neriah explained, "Scientifically speaking, this is new territory. We were astonished to see the extent to which microbiomes affect cancer mutations–in some cases, entirely changing their nature."