WHAT WAS CLAIMED
Fasting can cause the body to eat itself, removing all cancer and Alzheimer's cells.
OUR VERDICT
False. There's no evidence that fasting alone can cure cancer or Alzheimer's disease.
AAP FACTCHECK - The co-author of a study being cited with claims that fasting can remove all cancer and Alzheimer's cells from the body says that's not true.
The expert says that fasting may enhance other medical treatments, but it cannot cure cancer or Alzheimer's disease on its own.
The claim appears in a Facebook post that includes an image of Nobel Prize-winning cell biologist Yoshinori Ohsumi by the Healthy and Natural World website.
"When the human body is hungry, it eats itself, it does a cleansing process, removing all sick cells, cancer, aging cells, and alzheimer's," the overlay text on the image says.
The first comment includes a link to a 2019 Healthy and Natural World article examining the benefits of water fasting - consuming only water and abstaining from food for a specified time.
The article states that one of the greatest short-term benefits is a process called autophagy, whereby metabolic processes in the body eliminate dysfunctional cell components, helping to "recycle cells and protect against chronic health conditions and neuro-degenerative diseases."
Yoshinori Ohsumi is an expert on autophagy.
The article contains more nuanced statements, saying autophagy can help prevent cancer.
However, unlike the Facebook post, it does not claim autophagy can completely remove all cancer cells from the body.
The article also states that autophagy protects patients against the side effects of chemotherapy and radiotherapy.
The author cites two journal reviews to support this point: a 2018 review in Brazilian scientific publication Clinics on fasting-mimicking diets and their potential role in cancer therapy and a 2012 Cold Spring Harbour review on the role of autophagy in cancer treatment.
Both reviews said autophagy could suppress tumour development, but it also promotes tumour growth.
Neither review found that autophagy alone could cure cancer.
The article stated that fasting could also "play an important role in helping to protect against Alzheimer's disease and Parkinson's disease."
As evidence, it cited a single literature review to support this, a 2014 paper in the journal Cell Metabolism on fasting and neurodegeneration.
That review's co-author, Valter Longo of the University of Southern California, said fasting alone could not cure cancer through the process of autophagy.
"I always say that we have never cured a cancer in mice with just fasting but we have cured many types with fasting plus the most effective therapy already developed for that tumour," Professor Longo told AAP FactCheck.
However, he noted that fasting and diets mimicking fasting can make therapies much more effective, and clinical trials are underway to verify the results seen in animal tests.
Prof Longo also said different types of fasting can protect against Alzheimer's in mouse models, but indicated there was not enough evidence for humans.
"We are only beginning to understand the effects of fasting in human neurodegeneration," he said.
Ian Olver, a cancer researcher at the University of Adelaide, said all three reviews explored the link between fasting and autophagy, but the mechanisms have not been worked out.
While autophagy by fasting can increase cancer cell death in some cases, the retired oncologist said in others, it can cause cancers to grow.
"Does it kill all of the cancer cells? In mouse models, clearly not," Prof Olver told AAP FactCheck.
He said the three literature reviews indicated autophagy could eliminate some unhealthy cells; however, there was no evidence to suggest it could eradicate all cancer cells, which was essential for a cure.
"The articles are not suggesting fasting alone as a cancer treatment but in addition to other treatments like chemotherapy, and not for all cancers in all people," Prof Olver added.
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