More on nutrition

Back in the days, when I blogged from Grenoble, most posts were concerned with cycling.  This is how I spent much of my time outside the laboratory.  This was not to everyone’s liking.  Some friends wanted to hear from me but didn’t care so much about cycling.  Some complained to me about it.

I’m afraid this blog is shaping up similarly.  It is of course more monotopical than my previous writing.  You won’t read much beyond cancer.  This is not exactly a cheerful subject, but you know what to expect.  Or at least you thought so.  Within the limited scope of the blog, I have started to sharpen its focus considerably.  The last dozen posts have been almost exclusively about fasting.  Are you sick of this already?

I’m certainly sick of fasting, but I will use this post to summarize what I know about it and some closely related issues of nutrition.  I’m sure there’s much repetition from earlier posts, but I tend to forget things as soon as I write them down.  I could never write a coherent book of consequence.  What follows might still be worth reading.  There will be a few new things from a paper I’ve just finished reading.

The paper on the Effects of short-term fasting on cancer treatment has this statement right in the abstract:  “[Short-term fasting] reinforces stress resistance of healthy cells, while tumor cells become even more sensitive to toxins, perhaps through shortage of nutrients to satisfy their needs in the context of high proliferation rates and/or loss of flexibility to respond to extreme circumstances.”  This contrasting response of healthy and cancerous cells to starvation is called differential stress response.

Here are some of the things that happen in starved tumor cells:

• Glycolysis slows to a crawl (for lack of substrate).  Cells have little energy to sustain their obligatory proliferation.
• Oxidative phosphorylation results in oxidative stress and apoptosis.
• Increased translation drives cells to apoptosis because of unmet energy needs.
• They become more vulnerable to any kind of stress.
• High levels of reactive oxygen species raise the level of chemotherapy-induced DNA damage.
• Elevated antitumor immunity increases the efficacy of chemotherapy.

And this is what happens in healthy cells upon fasting:

• Over about 30 hours, the liver converts all stored glycogen to glucose.  It then switches to glucose synthesis.
• Circulating levels of insulin and insulin-like growth factor 1 decrease.  Cells are driven towards repair and maintenance instead of reproduction and growth.  This explains the increased resistance to chemotherapeutic agents.
• A low metabolic rate avoids oxidative stress and DNA damage.
• Hematopoietic stem cells and circulating immune cells become resistant to chemotherapy.  The patient’s immunity holds up better.

The paper goes on to describe short-term fasting as a clinical intervention in its own right.  Possible side effects include weakness and short-term weight loss.  This doesn’t really need to be spelled out, does it?  On the optimal length of fasting, the jury is still out.  The paper notes ominously that much longer periods might be required compared to what is studied in mice (24-48 hours).  If there were hard data, I’d be happy to give this a try, but for now I’ll stick to what I’ve been doing so far.

Also a bit unclear is the question of how best to break the fast.  Should I slowly ramp up or quickly eat as much as I can?  What should I eat?  A somewhat obscure reference mentions the danger of overfeeding after a period of fasting.  The glucose and insulin spikes will reaccelerate tumor growth.  How much does it take to spoil all the gains made through much pain?

A related issue is how to eat in the interfasting period.  The primary objective is regaining lost weight and strength.  The secondary objective is to withhold from the cancer what it requires for growth.  A diet rich in fat and protein but low on sugar is probably best.  But how far should I take this?

The absolute extreme is a ketogenic diet, where nearly all carbohydrates are removed.  This requires careful planning and management, great effort during shopping and cooking, and should probably not be done without medical supervision.  This is also not how I want to live.  Going without food for three or four days is not particularly pleasant.  In the intervening days, I want to enjoy what I eat.

Still, It’s probably wise to cut down on the carbs and maybe go as far as remove simple sugars.  No more chocolate, jam or ice cream.  Instead, I will have bacon and eggs for breakfast a few times a week and snack on nuts.  Against the zeitgeist and my own convictions, I will eat more meat and grease my food as much as possible.  I always knew butter was good for me.  Now it turns out I was right.  There couldn’t be a better way to end this post.