 Most people could name four of the basic tastes, sweet, sour, salty, and bitter. The rare foodie may be able to nail umami, but what about the forgotten flavor sense? Spicy. This seeming neglect is somewhat surprising, given that hot peppers are one of the world's most widely used spices. In fact, as many as one in four people on the planet currently eat chilies on a daily basis. Questioning the question, why is spicy food so popular? Why do some like it hot, enjoying what is at first glance in irritating and potentially painful mouth sensation? According to one popular suggestion, it is the endorphin hit, the release of the natural morphine-like painkiller chemicals from your brain. You hear this a lot in the popular press, but we still don't have any convincing evidence to support it. Another suggestion is that we learn to use it for its antimicrobial properties before the age of refrigeration, given that spicy food tends to be preferred by cultures living in warmer climates. And for that matter, maybe it makes us sweat, and thereby ultimately helps cool us down. Then again, maybe it's just because people just like the taste. Preference for spicy foods does seem to run in families, based on twin studies comparing the preferences of identical to fraternal twins. Genetic factors may account for up to half of the variation similar to the heritability of sweet and sour preferences. It may also be hormonal. Researchers in France noted that particularly males like spicy food and wondered if it was a testosterone thing. So they took a group of more than a hundred men and gave them a plate of mashed potatoes and asked them to basket the potatoes to taste. They're taking saliva samples to measure their testosterone levels. And what do you know? Men who had higher testosterone added more hot sauce. That may help explain this study that found a correlation between hot chili pepper consumption and muscle strength in adult males. As an aside, when I was looking at the testosterone literature, I ran across this study that showed young men experience an acute decrease in blood testosterone levels after chugging sugar water or whey protein powder. 12- to 18-year-olds were randomized to a few scoops of protein powder or about two cans of soda worth of sugar, and within 20 minutes saw a significant drop in testosterone levels compared to a sugar-free protein-free control. This is consistent with lower testosterone levels found in people on high protein, low-carb diets. Anyway, what does the consumption of hot spicy foods do to our lifespan? Well, a massive study of half a million men and women in China found that those regularly eating spicy foods had an associated 14% reduction in total mortality, meaning the risk of premature death. That could translate into about an extra year onto your lifespan, if it is cause and effect. Those of you who follow my work know that there are two main potential issues with observational studies, reverse causality and confounding factors. In other words, instead of spicy foods leading to less disease, maybe disease is leading to less spicy food, with sick people eating blander diets. However, the apparent benefit remained even after excluding sick folks, or those who were just about to croak. And so, reverse causality doesn't seem to explain it, though, hey, people who eat spicy food probably drink more, and what do they drink in China? Green tea. So maybe that's what's going on. I mean, it'd be nice to replicate this in a non-green tea drinking country, or even a country that drinks terrible stuff, like the United States. And yet, same thing, a 13% risk reduction in premature death. And the protective association remained even after controlling for Mexican-American ethnicity. As I detailed before, they have a longevity advantage, presumably because they eat so many beans. Same thing was found in Italy, this time a 23% lower all-cause mortality. That'd be like two extra years of life. The authors include that minor dietary changes, such as just adding chilies to one's usual diet, could be a valuable measure for improving health. Even four studies done overall, including this one in Iran, that all found the same thing, significantly lower risk of premature death. In fact, black or chili pepper consumption was associated with about the same lifespan extension as turmeric, even at just like a pinch a day. And those who did both seem to do even better, which is consistent with the ability of a black pepper compound to boost the bowel availability of the turmeric compound curcumin. I've got about 50 videos on why turmeric is so good for you, but why might chili peppers extend your life? We'll find out next.