Friday, February 10, 2017

Spicy Food and Bad Science

The latest science "news":
Our objective was to analyze the association between consumption of hot red chili peppers and mortality, using a population-based prospective cohort from the National Health and Nutritional Examination Survey (NHANES) III, a representative sample of US noninstitutionalized adults, in which participants were surveyed from 1988 to 1994. The frequency of hot red chili pepper consumption was measured in 16,179 participants at least 18 years of age. Total and cause-specific mortality were the main outcome measures. During 273,877 person-years of follow-up (median 18.9 years), a total of 4,946 deaths were observed. Total mortality for participants who consumed hot red chili peppers was 21.6% compared to 33.6% for those who did not (absolute risk reduction of 12%; relative risk of 0.64). Adjusted for demographic, lifestyle, and clinical characteristics, the hazard ratio was 0.87 (P = 0.01; 95% Confidence Interval 0.77, 0.97). Consumption of hot red chili peppers was associated with a 13% reduction in the instantaneous hazard of death.
Does this show that eating chili peppers will make you healthier? No. What is shows is that healthier people eat more chili peppers.

Sick people don't like spicy food. Some of them are so sick that they soon die. As a result, the numbers show that people eating chili peppers live longer. This is really not complicated. But we have professional dietary "scientists" claiming the reverse and getting their results into peer-reviewed publications, complete with P values and confidence intervals.

Maybe I'm wrong and they are right, but I would bet on my interpretation because literally dozens of claims like this have been made for the health effects of various foods, and hardly any of them have been verified.

And you wonder why so many people have no respect for science.


Shadow said...

And, of course, these studies make it to the news (everybody eats), including follow-up studies that say never mind. And then the cycle repeats itself. I'm waiting for the study that shows people who eat eggs on Sundays live longer than those who eat them on any other day. Perhaps the old saying "everything in moderation" applies more than the "science."

G. Verloren said...

These sorts of junk science studies exist because our economic system incentivizes them over more rigorous studies.

Basically, when you tie money to science, you end up with the science being perverted to serve the interests of whoever stands to make money. This is why doctors throughout the 20th century used to commercially endorse cigarettes, and why "snake oil" and other "patent medicines" in the 19th century were so abundant.

Capitalism innately favors thieves, liars, and conmen, and unless we impose strict regulations and vigilantly enforce them, such scoundrels thrive in abundance at the expense of the innocent - both the people they scam, and the legitimate medical experts they undermine the authority of with their frauds.

We don't do nearly enough to prevent this sort of junk science - just as we don't do nearly enough to prevent lies and cheats of all kinds within our society.

It ought to be astonishingly illegal to abuse the public trust. Politicians who lie ought to be stripped of their office. Police officers who shoot unarmed civilians ought to be convicted of murder. Lawyers who obtain convictions for people who are later proven to be innocent should be made to serve the sentence they secured. Bankers and brokers should be required to act as fiduciaries, so that if their clients lose money, they do too. Pharmaceutical companies should be barred from influencing doctors to prescribe their products, and from buying monopoly rights for existing medications and jacking up the price in the pursuit of profit. And on, and on, and on.

But no, our society recoils from the notion of holding people responsible for the harm they cause. And the people with the power to change things are exactly the same people benefitting from having the deck stacked in their favor, so there's no real incentive for them to crack down on abuses. Convenient, that.

leif said...

and G, did you see it's shortly to become worse? T just signed an executive order requiring each new regulation enacted to destroy two others. you can see how this weaponizes the regulatory environment; if a already trumpist EPA enacts a new bogus regulation, it gets to name two others to axe -- and you know those will be important.