First demonstration of fasting-mimicking combined with oral vitamin C as an effective cancer treatment

In studies in mice, the researchers found that the combination slowed tumor progression in multiple mouse models of colorectal cancer, and in some mice it led to disease regression

"We show for the first time how a completely nontoxic intervention can be effectively treated," said the study's corresponding author, Valter Longo, professor of geriatrics and biological sciences at the USC Longevity Institute.

While fasting remains a challenging option for cancer patients, a safer and more feasible option is a low-calorie, plant-based diet that allows cells to respond, the researchers said

Their findings suggest that a less toxic treatment, one that mimics fasting plus vitamin C, has the potential to replace the more toxic one

Previous studies on the anticancer effects of vitamin C have been inconsistent

"Our first in vitro experiments showed dramatic effects," Longo said

Longo and his colleagues found this strong effect only in KRAS-mutated cancer cells, which is considered one of the most challenging targets in cancer research

These mutations in the KRAS gene suggest that the body is resistant to most anti-cancer treatments, which reduces patient survival

The study also provides some clues as to why previous research on vitamin C as a potential anti-cancer therapy has shown limited effectiveness

On its own, vitamin C treatment appears to protect cancer cells by raising levels of ferritin, a protein that binds iron, triggering KRAS mutant cells

In this study, the scientists also found that colorectal cancer patients with high iron-binding protein levels had lower survival rates

"In this study, we observed how rapidly a dietary cycle mimicked the efficacy of vitamin C drug doses in KRAS-mutant cancers," said study co-author Maira Di Tano of the IFOM Molecular Oncology Research Center in Milan, Italy

Previous research by the research team has shown that fasting and fasting-mimicking diets can slow cancer progression, making chemotherapy more effective on tumor cells, while protecting normal cells from chemotherapy-related side effects

In mouse models of breast cancer and melanoma, the combination enhanced the immune system's antitumor response

Scientists believe that treating cancer will eventually use less toxic drugs, like antibiotics are used to treat infections that kill certain bacteria, but if the first drug doesn't work, other drugs can be substituted

To get there, they said, they needed to first test two hypotheses: Their drug-free combination intervention would work in mice and look promising in human clinical trials

At least five clinical trials, including one at the University of Southern California in breast and prostate cancer patients, are studying the effects of a simulated fasting diet combined with different cancer drugs
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Maira Di Tano et al, Synergistic effect of fasting-mimicking diet and vitamin C against KRAS mutated cancers