LOS ANGELES—A low-calorie diet that mimics the effects of fasting has been shown to help strip away a protective barrier on breast and skin cancer cells, allowing the immune system to recognize and attack them, according to a new study on mice led by the University of Southern California (USC).
The fasting-like diet low in calories, protein, and sugar was used along with chemotherapy in the study published in the journal Cancer Cell this week. It was led by Valter Longo, professor and director of the USC Longevity Institute at the USC Leonard Davis School of Gerontology.
“[It] is the first study to show that a diet that mimics fasting may activate the immune system and expose the cancer cells to the immune system,” said Longo. “This could be a very inexpensive way to make a wide range of cancer cells more vulnerable to an attack by the immune cells while also making the cancer more sensitive to the chemotherapy.”
The results of the study are particularly interesting since chemotherapy is known to suppress the immune system.
Cancer cells are protected by “T regulatory” cells, which trick the immune system into thinking cancer cells should not be killed. But the fasting-like diet caused these cells to be expelled, prompting a 33 percent increase in the levels of cancer-fighting white blood cells and a doubling of the number of stem cell-like progenitor cells in the bone marrow. The change also made it easier for chemotherapy drugs to attack the cancer.
Four days of the fasting-like diet was found to be just as effective as two days of a water-only, short term starvation diet.
Longo said it’s possible such natural mechanisms exist in the immune system to protect people from disease.
“It may be that by always being exposed to so much food, we are no longer taking advantage of natural protective systems which allow the body to kill cancer cells,” said Longo. “But by undergoing a fasting-mimicking diet, you are able to let the body use sophisticated mechanisms able to identify and destroy the bad but not good cells in a natural way.”
The study was built upon prior research that showed a short-term fast starves cancer cells and helps chemotherapy to better target the cancer. Longo also published another study recently showing that fasting is safe for human patients and may protect against chemotherapy’s side effects.