My n=1 case for spicy foods.
I have a secondary systemic inflammation to due a genetic condition that make my mitochondria to malfunction. Usual symptoms include a profound fatigue after working-out and muscle weakness, specially in the extra-ocular muscles.
I have been always centered around supplements to improve the energy output (ATP) of my mitochondria (Coq10, ALCAR, idebedone ... you name it). While this made a big difference in my everyday energy levels, I always felt that this systemic fatigue couldn't come only from a energy deficit, as I was able to workout with pretty good intensity and decent weights (I can squat 1.5 my body weight).
The first hint came a couple of months ago when a friend of mine went to the doctor because he was also profoundly fatigued and the doctor told him that he had some kind of auto-immune disease that was causing a systemic inflammation and this systemic inflammation was likely the main cause for the fatigue.
The second hint came right here from HN [1]. So, I just added turmeric extract to my daily regimen 10 days ago and the results have been really impressive so far. I can recover much easier from my workouts and my general energy level has also improved a lot, specially during the mornings. It is too soon to tell, but after so many years trying so many supplements I have developed a anti-placebo and anti-bullshit sense for all these things, and this one is working for real.
Now, I am not meaning that spicy food will make you live longer, but it seems clear that they have some potent active substances that "do" something in our bodies.
I am now trying to add some spicy foods to my meals. The first one has been a very simple curry rice with black pepper (to improve absorption) to eat it post-workout.
Some relevant references:
Curcumin database [2]
Good general info about turmeric [3]
Mitochondria as a target in the therapeutic properties of curcumin [4]
[1] https://news.ycombinator.com/item?id=9960441
[2] http://www.crdb.in/
[3] http://www.whfoods.com/genpage.php?tname=foodspice&dbid=78
[4] http://www.ncbi.nlm.nih.gov/pubmed/25243820