As with all studies, there are nuances and limitations and this is by no means a final verdict. However, the results are promising.
First the researchers took a group of mice and had them follow a “16:8” eating protocol, in which they consumed all of their calories in an 8 hour window each day, and fasted the other 16 hours (for example, eating all food between noon and 8pm, then consuming only water between 8pm and the following noon). They were able to demonstrate that the mice experienced a significant increase in certain anti-cancer immune cells and proteins in their blood.
So far so good, but of course mice are not humans, so the scientists next repeated the same experiment in a group of human patients with colon cancer. Fortunately, they found similar changes to immune function in the human cancer patients when compared to matched controls. Basically, they found biochemical evidence that fasting weakened tumor cells and strengthened the immune cells that fight cancer.
Again, so far so good, but favorable lab changes are not definitive proof of better outcomes. So they then also followed the clinical course of the fasting cancer patients and found that, compared to a control group of non-fasting cancer patients, they had a better response to chemotherapy, with more shrinkage of their tumors.
There are lots of reasons to be cautious in interpreting this study. It was small, which increases the possibility that we are just witnessing a fluke. It was only in colon cancer, so may or may not apply to other cancers. It was performed on an ethnically homogenous set of patients, so may or may not be applicable to people of non-Asian background. It was done in patients with established cancer, so may or may not have anything of use to say about preventing cancer. And it did not look at the most important outcome, namely did any patients actually have a longer and/or higher quality of life via fasting.
Nonetheless, the fact that the researchers were able to document BOTH a mechanistically plausible reason why fasting might improve cancer treatment outcomes AND actual evidence of an improved response to chemotherapy is strongly suggestive that they are onto something. So too is the fact that this study comes on top of other studies showing benefit in colorectal diseases from intermittent fasting (see again my prior post about fasting and Crohn’s disease).
Finally, as I frequently point out, lifestyle interventions such as intermittent fasting have very little downside. They don’t cost money, typically don’t have dangerous side effects, and don’t require a prior authorization from your insurer. So even if the benefit of a particular lifestyle intervention is quite small, the risk/reward ratio is usually still likely to be favorable.
As always, my thoughts on this blog do not constitute medical advice. Please discuss with your own doctor before making any healthcare decisions.
