Is it okay to fast during chemotherapy? - News & Updates • Breast Cancer Foundation NZ

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Is it okay to fast during chemotherapy?

Is it okay to fast during chemotherapy?

A new study has found that a fasting mimicking diet can make neo-adjuvant chemotherapy more effective in patients with breast cancer.

The trial had 129 patients with HER- stage 2/3 breast cancer follow either a fasting mimicking diet or their usual diet for three days before and the day of their chemotherapy. A fasting mimicking diet is a low-calorie, low-protein diet that mimics the effects of a water-only fast. In this study, it included soups, broths, liquids and tea, all of which were plant-based.

It’s thought that fasting can help in cancer treatment because it signals healthy cells that it’s time to conserve energy as there’s low levels of nutrients around. In doing so, they switch to a quiet, maintenance mode. But cancer cells don’t listen to the body’s signals and so they continue to divide quickly, making them a prime target for chemotherapy. In this way, fasting can help protect healthy cells from the side effects of chemo while making cancer cells more vulnerable.

As part of this study, patients received either the fasting diet and chemotherapy or the anti-nausea drug dexamethasone and chemotherapy. Notably, side effects across the two groups were similar, suggesting that a fasting mimicking diet may be as effective as dexamethasone in reducing side effects from chemotherapy. Those on the fasting diet also saw less damage in normal lymphocyte cells after treatment, compared to the control group, and had better response to chemotherapy too.

While a fasting diet may sound quite extreme, 22 out of the 65 patients (around 33%) followed the diet for at least four cycles of chemotherapy, and 20% stuck with the diet through their whole chemotherapy treatment. The main reason for stopping the diet was a dislike of certain parts of the diet, which researchers suggest may have been a side effect of chemotherapy.

The study is the latest to show the benefits of various types of fasting during chemotherapy treatment. Previous studies have found that it can protect health cells against stressors, like chemotherapy, while making cancer cells more vulnerable to treatment.

You can read the full study here.