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spice

el-yucateco-green-lg I’ve been traveling a lot this summer. So I’ve had to have a “go-to” hot sauce that I can have on my person. A lot of restaurants have the standard trio of Sriracha, Tabasco, and Tapatio (and like free wi-fi, the higher end restaurants are the least stocked with the sauce). They’re serviceable, but they are to hot sauce what Wendy’s, McDonald’s, and Burger King, are to hamburgers. So often I try and make it to a market with a large Mexican food section and see if there’s anything that is palatable. The worst situations you encounter are when you go into a Food Co-op, because some of the buyers seem to think that carrot juice with a tincture of paprika will suffice as long as it is organic and locally sourced. Well, I settled on El Yucateco Green Habanero Hot Sauce for this trip. I’ve had it before, and it’s not the most distinctive in flavor, but I’d give it a straight B. It has a kick, it doesn’t have conflicting tastes, and the aftertaste doesn’t linger excessively.

Rock_Rousey_WM31 So as you might know, I like my hot sauce. I’m the Ronda Rousey of hot sauce consumption. If you think you can handle it, bring it. I’ll be at ASHG 2015 in Baltimore in a few months. I threw down the gauntlet. I’m game if anyone who wants to challenge me in downing sauce or pepper, with the proviso that they can’t be double null on TRPV1. The “puny human” David Mittleman rashly took up my challenge. We’ll see if he’s all talk.

I bring up the sauce because the media is going crazy over a new paper. Here’s The New York Times, Eating Spicy Food Linked to a Longer Life:

Study participants were enrolled between 2004 and 2008 in a large Chinese health study, and researchers followed them for an average of more than seven years, recording 20,224 deaths. The study is in BMJ.

After controlling for family medical history, age, education, diabetes, smoking and many other variables, the researchers found that compared with eating hot food, mainly chili peppers, less than once a week, having it once or twice a week resulted in a 10 percent reduced overall risk for death. Consuming spicy food six to seven times a week reduced the risk by 14 percent.

This is a Chinese study. The sample sizes are large. I went to the original paper. It’s ungated, read it, Consumption of spicy foods and total and cause specific mortality: population based cohort study. I wanted to check out how robust this result was. Well, look at the figure at the top of this post. I wouldn’t say it’s a slam-dunk. The effect is weak in some subgroups, and goes away for those who drink. But the general trend is clear. There does seem to be a negative correlation between mortality and higher spice consumption across many subpopulations. They claim to have controlled for a lot of demographic variables, and I sort of trust them. But it’s really nice to see this sort of figure that lays it all out.

I’m not sure that they really smoked out all the correlations. After all, those who like the taste of spice could simply be superior human beings. How can you control for that confound? But in any case, I did stumble on this interesting related paper, Mice That Feel Less Pain Live Longer:

To investigate further, researchers from the University of California (UC), Berkeley, bred mice without a pain receptor called TRPV1. Found in the skin, nerves, and joints, it’s known to be activated by the spicy compound found in chili peppers, known as capsaicin. (When you feel like your mouth is burning after eating a jalapeño, that’s TRPV1 at work.) Surprisingly, the mice without TRPV1 lived on average 14% longer than their normal counterparts, the team reports today in Cell. (Meanwhile, calorie restriction—another popular way of lengthening mouse lifespans—can make them live up to 40% longer.) When the TRPV1-less mice got old, they still showed signs of fast, youthful metabolisms. Their bodies continued to quickly clear sugar from the blood—a trait called glucose tolerance that usually declines with age—and they burned more calories during exercise than regular elderly mice.

…Already, diets rich in capsaicin have been linked to lower incidences of diabetes and metabolic problems in humans, he notes. So might spicy foods be a way of extending life? Maybe, Dillin says, but you’d have to eat a lot of them over a long period of time. “Prolonged exposure to capsaicin can actually kill the neuron” that transmits signals from TRPV1, he explains. Knocking out those signals might mimic the effects of being born without TRPV1 in the first place and, therefore, could lead to a longer life.

Yes, a friend of mine with a neuroscience background told me he suspected that I’ve knocked out all the neurons that handle signals from TRPV1. The 14% mortality reduction is interesting, because it’s in the same range as the human study above. But, you aren’t going to live 40% longer if you engage in calorie restriction. There’s only so much you can extrapolate from mice.

People have been worried and curious about my spice consumption for years. When people ask if there’s a reason I put this stuff in my mouth my response is straightforward: it tastes good.

620px-Awadhi_prawns When I was a kid shrimp was my favorite food. I’m Bengali at least to that extent. Today shrimp is still my favorite food (and I can report that the preference is heritable). But, shrimp is high in cholesterol. When I was growing up people were scared of cholesterol and fat. Doctors advised my mom to reduce our shrimp intake. It really made me sad, and I’m not a particularly food obsessed person. Give me shrimp, hot sauce, and some fruit, and I’m good.

Well, you know by now that the guidelines against dietary cholesterol intake have been pretty much dropped. Turns out that dietary intake is irrelevant for most people. And now there’s this: Dietary cholesterol and cardiovascular disease: a systematic review and meta-analysis:

Results: Forty studies (17 cohorts in 19 publications with 361,923 subjects and 19 trials in 21 publications with 632 subjects) published between 1979 and 2013 were eligible for review. Dietary cholesterol was not statistically significantly associated with any coronary artery disease (4 cohorts; no summary RR), ischemic stroke (4 cohorts; summary RR: 1.13; 95% CI: 0.99, 1.28), or hemorrhagic stroke (3 cohorts; summary RR: 1.09; 95% CI: 0.79, 1.50). Dietary cholesterol statistically significantly increased both serum total cholesterol (17 trials; net change: 11.2 mg/dL; 95% CI: 6.4, 15.9) and low-density lipoprotein (LDL) cholesterol (14 trials; net change: 6.7 mg/dL; 95% CI: 1.7, 11.7). Increases in LDL cholesterol were no longer statistically significant when intervention doses exceeded 900 mg/d. Dietary cholesterol also statistically significantly increased serum high-density lipoprotein cholesterol (13 trials; net change: 3.2 mg/dL; 95% CI: 0.9, 9.7) and the LDL to high-density lipoprotein ratio (5 trials; net change: 0.2; 95% CI: 0.0, 0.3). Dietary cholesterol did not statistically significantly change serum triglycerides or very-low-density lipoprotein concentrations.

Nutritional science in general doesn’t kill directly. Perhaps some people have type II diabetes because of the fat fear years when they gorged on Snackwells. But the biggest impact is that overreaction, and to a great extent craven behavior in the face of politicians looking for The Answer, results in reduced quality of life for tens millions. That matters. You sure as hell are going to get more skepticism from me about how something that I put in my mouth is good or bad from me now.

Do I hope that eating a lot of spice is healthy for me? Yes. Do I believe that this is a true result that will hold over time? Hell if I know. I’m just going to continue eating tasty food. End of story.

 
• Category: Science • Tags: Nutrition 
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SnackWells

SnackWells

I am a child of the 1980s and early 1990s. Therefore I remember many things which I would perhaps like to forget. One of those things is the monomaniacal fixation on “low fat” which permeated our culture during the decade before the internet became mainstream. My mother used to buy us boxes and boxes of SnackWells fat-free cookies, which it turns out are almost a pure concoction of white flour and sugar. In The Big Fat Surprise: Why Butter, Meat and Cheese Belong in a Healthy Diet Nina Teicholz recounts that this brand of cookie was so popular that the manufacturer had to ration it across the distribution chain, they just couldn’t keep up with demand. Teicholz’s book basically seems an update of Gary Taubes’ Good Calories, Bad Calories. Many of my friends live and die by Taubes’ body of work, mostly because it produces results which are sustainable for them. The revolution in our perceptions of nutrition over the past generation can be summarized by the fact that The New York Times is willing to publish an article with this title: Study Questions Fat and Heart Disease Link.

What to think if you are a “well informed” person when the information changes so often and quickly? Melinda Wenner Moyer’s article in Aeon, Against Grain, is a good place to start. She observes:

In the midst of all the claims and counterclaims, there is a single clear piece of common ground. Experts of every stripe ask dieters to avoid refined sugars and grains. ‘Losing body weight on a plant-based diet is much less likely to occur if the diet includes too many refined carbohydrates,’ writes Cornell’s T. Colin Campbell in his book, The China Study, based in part on his Cornell-Oxford-China study research. Esselstyn instructs his dieters to consume only whole-grain products and avoid fruit juice. And McDougall urges his readers to eat complex carbohydrates instead of refined sugars and flours.

So where does all this leave us, other than confused and wondering if we should stop eating cupcakes? On the health side, the science does collectively suggest, but not prove, that a calorie is not always just a calorie, and that carbohydrates – particularly refined ones – might have unique metabolic effects that increase risk for chronic disease. Indeed, the notion that sugar and refined carbs are dangerous seems to be the one point on which nutrition scientists at either end of the carb-fat spectrum agree. I suspect that my weight-loss success a decade ago had something to do with the fact that, by cutting out wheat, I was replacing some refined carbohydrates with other macronutrients.

The problem here is what Jim Manzi in Uncontrolled terms “high causal density.” The most famous researchers, such as Dean Ornish and Robert Atkins, tend to present you with one-size-fits-all strident solutions. But the fact is that there are people who remain thin, who do not exercise, and consume processed carb and sugar.* I know them, and you probably know them. There are many factors which go into the end product of a person’s physical appearance and overall morbidity risk. On an aggregate scale of societies a few significant variables changing can result in enormous differences in outcomes, but people need to see efficacy on the individual level, and the causal signals can be confusing (in particular if efficacy varies from person to person for the same regime!).

A bigger issue has been institutional health’s monomaniacal focus on fat and a few biomarkers has left many not trusting scientific recommendations. That focus is shifting, as science does update. Unfortunately the generation of new robust inferences is noisy and prone to dead ends in domains of high causal density. This is not always the case in public health. It turns out that the model of germ theory is not too subtle; it describes the world in pretty uncomplicated terms. Similarly, why and how vaccines work is tractable because the etiology of how you get polio is much easier to tackle than how you get type 2 diabetes. In all likelihood there are many ways to get type 2 diabetes, and multiple factors impact different people at different weights (e.g., there are people with a greater genetic disposition to type 2 diabetes given the same exercise and nutritional regimes, though one might be able to explain this with something like the nature of fat deposition).

This reality of science as a messy and iterative process is obvious to anyone who practices science. A year ago I had a conversation with a friend who happens to be a professor of biology at a university, and we were talking about the problems with convincing the public about the efficacy of vaccination. He admitted that he had a bit of guilt in this area because when it came to his own health he took a very critically-rational perspective as to what his physicians told him. As someone who was aware of the protean nature of scientific literature he had no great confidence that the recommendations from on high were definitive or the “final answer.” Another friend who is a medical doctor did admit to me that for him patients who had a good science background were a pleasure to work with because for them healthcare was a collaborative process in which they were active participants, instead of being recipients of his commands ex cathedra. This reality is why I am somewhat uncomfortable with the “Because Science” meme. It attributes to science almost Solomonic powers of judgment, and in actuality is wielded to reinforce the prior conceptions of interlocutors.

Where does that leave us? Describing a problem is not a solution, and due to the nature of the reality here there isn’t an easy answer. But it does imply to me that we should be cautious about engineering aspects of human life when the scientific basis for that engineering is less than certain. The war on fat and salt over the past few generations have been due to putting science forward as the basis of policy which turned out to not be robust. In the case of salt the establishment has even done an about face, “the government says there is no good reason based on health outcomes for many Americans to drive their sodium consumption down to the very low levels recommended in national dietary guidelines.” Salt tastes good, so one can imagine just how much utility was left on the table because people changed their diet to become more insipid. Policies have consequences.

cupcake-red-velvetIncreasingly new way of thinking about diet has been to focus less on the latest science, and fall back on cultural culinary history. “Eat like your grandmother cooked” is trendy advice proffered by influential writers such as Mark Bittman and Michael Pollan. But by removing heavily processed foods it might be a major upgrade from modern diets, which are designed to sustain the profits of the food industry, not our own health (that’s a negative externality, the cost of which they don’t have to eat). Whether you go mostly plant-based or carnivorous, you’re probably going to be fitter in either direction, even if one is superior to the other at the end of the day.** Instead of deduction from what we know, anengineering an appropriate nutritional outcome, in the best course of action in the near future is probably “hipster nutrition.” Artisan hand-crafted diets which look back to the past, though in a non-ironic fashion, might be the best way to go because they’re the outcome of hundreds of years of innovation and experimentation. If you don’t have randomized control trials, go with the next best thing. History.

* Whether they are healthy is a different question obviously.

** One issue is that the different options might be superior for different people.

 
• Category: Science • Tags: Nutrition 
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Razib Khan
About Razib Khan

"I have degrees in biology and biochemistry, a passion for genetics, history, and philosophy, and shrimp is my favorite food. If you want to know more, see the links at http://www.razib.com"