A juice detox, a water fast, or a soup diet are often talked about as ways to stimulate healthy weight loss, cleanse toxins from the muscle tissues, and more. But what about tumor suppression?

Preclinical evidence suggests that short-term fasting and fasting mimicking diets can protect healthy cells against chemotherapy, while simultaneously rendering cancer cells more vulnerable to the treatment. However, clinical research evaluating the potential of short-term fasting in patients with cancer is in its infancy. 

This was shown in a new paper published in Nature: Communications by scientists from Leiden, The Netherlands, which looked at a fasting-mimicking diet in patients undergoing chemotherapy for the most common form of breast cancer.

In a trial conducted by Dr. Judith Kroep and colleagues, 129 patients with HER2-negative stage II/III breast cancer followed either a fasting mimicking diet or their regular diet for 3 days prior to and during neoadjuvant chemotherapy (treatment given as a first step to shrink a tumour before surgery).

Of all breast cancer patients, around 80-85% have the HER2-negative variety, but according to Dr. Kroep, animal studies suggest fasting mimicking diets could also be effective for other forms of cancer, and that possible future studies could expand this field of research.

Fasting and cancer

The logic, without having a Ph.D. in biology, is two-fold. Cancer cells thrive on carbohydrates, and meat, particularly red meat, is rich in amino acids that increase the expression of insulin growth factor-1 (IGF-1) one of the body’s primary growth-hormone signals for muscle and tissue growth.

An individual with cancerous or precancerous cells that eats a diet containing a large amount of meat without incorporating an exercise regimen that involves sufficient hormetic stress, i.e. the breakdown of muscle fibers, is in theory at risk of providing IGF-1 to precancerous cells, allowing them to live past normal cell-cycle checkpoints and to possibly become malignant.

In the study, Dr. Kroep followed a program pioneered by Italian biologist Dr. Valter Longo, Director of the Longevity Institute at the University of Southern California and author of The Longevity Diet. What is described in the study and known as the “fasting mimicking diet,” is a mode of eating that allows your body to continue to behave as if it is calorie-restricted, a metabolic state known to be good for preventing cancer, but that doesn’t involve properly fasting.

“The culmination of 25 years of global research on aging, nutrition, and disease, this unique combination [is] an easy-to-follow “everyday” diet and short periods of fasting-mimicking diet (FMD),” reads Dr. Longo’s website.

The trial

“The [randomized controlled phase 2] trial,” has been the only one to date in dietary cancer management with “efficacy as an endpoint,” Dr. Kroep told World at Large.

The fasting mimicking diet used was a plant-based, low amino-acid substitution diet, consisting of soups, broths, liquids and tea. Macronutrient ratios and amounts were fixed and not personalized, and a micronutrient supplement was added.

Although no difference in toxicity was observed between the treatment and control groups, the effects of neoadjuvant chemotherapy on tumour response were reinforced in patients in the fasting mimicking diet group.

One potential drawback is that the 129 individuals in the trial and those in other studies were “relatively fit” and that unfit patients, or those with metastatic disease who are less-fit to lose weight, may have different outcomes.

However the results of this study suggest that cycles of a fasting mimicking diet are safe and effective as a supplement to chemotherapy in women with early breast cancer. These findings, together with preclinical data, encourage further exploration of the benefits of fasting combined with cancer therapy.

“This study is a stepping stone in cancer dietary management. More studies are needed to confirm our finding and extend them to other cancer types,” says Kroep. “We plan to do some of that work.”

Continue exploring this topic — What if There Were a Drug That Tricked Your Body into Thinking it was Fasting?