Food is a potent inducer of metabolic responses (and pleasure). Specific nutrients enhance muscle action, while others boost appetite or modulate inflammatory responses. On the other hand, caloric restriction under normal conditions ( 20 to 40 % fewer calories than required ) has been shown to protect against the development of chronic diseases. ( To highlight this : there was hardly any diabetes or gout in post-war Germany ) Exploiting the differential effects of food or its absence during disease may be one strategy to enhance the efficacy of drug therapies.
Significant improvements in the field of oncology ( = cancer treatment ) have enhanced prevention, screening, early diagnosis and treatment. Nevertheless, the possibility that a patient’s response to anti-cancer therapy might be improved through changes in diet is attractive, affordable and readily accessible.
Normal body cells and cancer cells differ in their ability to respond to fasting. In the absence of nutrients, normal cells switch their metabolism toward pure maintenance, whereas tumor cells are unable to activate this protective response and cannot stop growing.
Researchers found that short-term starvation with restriction of glucose and other growth factors increased the sensitivity of yeast cells ( !! ) to chemotherapy. A similar effect was observed on mice : 48 to 60 hours of food deprivation ( scientific argot for “starving”..) retarded tumor growth. In some cases the effect was as big as the effect of chemotherapy. In another experiment it was observed that fasting potentiated the effect of chemotherapy on melanomas and breast cancer cells in mice ( !! ) ( SciTranslMed 2012;4:124ra27 ).
These are very exciting results and trials are under way to integrate caloric restriction into the current comprehensive approach in cancer treatment. In a trial of 10 patients with cancer who voluntarily underwent short-term fasting prior to or after chemotherapy, fatigue, weakness, and gastrointestinal side effects were reduced (NEJM 366;24:2319).
Put these findings in a cultural context : be it Red Indian natives, Muslims or Christians – there is always periods of fasting somewhere. If these periods of fasting kept up over a lifetime prevent the development of cancers because the cancer gets “starved to death” at a very early stage remains to be investigated. Even the idea of “cleansing” in esoteric or alternative medicine goes this way (with a big difference though : one does not need any exotic concoction or bowel rinsing – just stop eating).
Funnily enough a dear patient of mine brought the fasting-topic up just recently. We had a good chat, if we should start a once-yearly fasting group somewhere up in the hills, where shops and restaurants are out of walking distance. I believe it would be a good idea and I am convinced that a fasting-group gives the members enough emotional and social backup to be able to do it.
The first 3 days are difficult – but everybody can do it with a little help from the friends. It’s all in the mind – even eating. There is no harm for a reasonably healthy person to fast if a few very basic rules are observed. And believe it – the author has experienced it himself some years ago : after 3 days of fasting one can walk past any deliciously smelling bakery or restaurant without getting ravenous.
I would be delighted to get some feedback on this proposition.