Louie Helm recently got worried that “Asparagus Metabolizes Into Neurotoxin Over 5x More Powerful Than PCP”. Eliezer read his post and got pretty worried too:
Yikes. Until and unless someone debunks this, asparagus is permanently off my menu. Seriously, yikes.
(To Eliezer’s credit, he admitted a successful debunk from James Wu in the comments about 45 minutes after he initially posted.)
One of Eliezer’s favorite topics is “civilizational inadequacy”—roughly, the idea that there are tons of huge gaping problems everywhere, that “any sane civilization” would fix immediately, but we still have them because civilizational inadequacy. (See here for a sort of gestalt overview, or here or here for other mentions.)
The observation that civilization is inadequate is obviously correct to some degree: sometimes people do dumb things and sometimes large groups of people are dumber than the maximum of their parts. There’s nothing new (or controversial) there. My problem is with acting on priors heavily informed by civilizational inadequacy. Civilization may be inadequate, but quite a lot of the time it’s still more adequate than any individual person complaining about it.
The asparagus scare is an obvious example. It takes pretty extreme belief in civilizational inadequacy to hear the allegation that your body has been metabolizing the neurotoxin equivalent of four typical doses of PCP every time you eat a serving of asparagus, and not wonder anything like:
why the equivalent of two strong doses of PCP don’t have any side effects that you actually notice
why any of the numerous people who wrote about asparagine being metabolized into DMSO didn’t raise any alarms
why any of the papers you cited on DMSO neurotoxicity didn’t wonder about the implications for the effects of people not experiencing medical-level dosages of highly-concentrated DMSO
Any of these concerns, or any hope that civilization might actually be adequate, should compel one to check the sources and math with a bit of skepticism before publishing, at which point you’d find all the excellent points that James Wu mentioned in the comments.
Appendix: James Wu’s debunking of the article
I’m very disappointed in the quality of this article. It reads like clickbait fearmongering, and while it at least cites sources, its understanding of the sources is sorely lacking. The author seems to confuse studies describing effects of local concentrated doses with overall dose, and in vitro studies with food toxicology in general.
Article #1, “Unexpected low-dose toxicity of the universal solvent DMSO”, describes what happens when you inject 5 μl of 1% DMSO into the eye, and seeing resulting damage to the retina. Describing that as “However, in recent years, researchers have found that as little as 0.000015mg of DMSO is enough to permanently destroy neurons in rats” is… really, really, really bad science journalism.
For one, the toxicity of DMSO in the eye in general is well-known, and is not some sudden discovery (http://www.ncbi.nlm.nih.gov/pubmed/1124535). To specifically not call retinal damage as-is, and instead say “destroy neurons” with all the generalized connotations that it carries, is disingenuous at best.
And notice the key point. 1% DMSO! The study did not find what would happen if those 5 μl were ingested by the rat, as the article’s writeup seems to imply; they injected that 1% solution directly to the eye! Then surveyed for retinal damage! Using the fact that local cells die when being injected with 1% concentration of undiluted [chemical of choice] to argue that [food containing chemical] should never be eaten is such fearmongering as to make the Food Babe proud.
The safety profile of aspartame, for example, is one of the most well-studied topics in food additive history. At this point the evidence for its safety is better than most over-the-counter drugs. Aspartame metabolizes into methanol. Should we judge the safety of aspartame based on what happens when we inject methanol into the eye?
The conclusion of article #1 doesn’t say “researchers suggest more research on the toxicity of DMSO-containing substances in humans”, as it surely would if they at all thing it had human toxicity implications. Instead it says “compute absolute DMSO final concentrations and include an untreated control group in addition to DMSO vehicle control to check for solvent toxicity.” Because that’s where it’s relevant, for researchers using DMSO to carry other compounds in lab settings. And not, as implied in general food toxicology.
And finally, where did 0.000015mg come from? I can’t get that number. At all (https://www.wolframalpha.com/input/…)
Article #2, “DMSO Produces Widespread Apoptosis in the Developing Central Nervous System”, again tests in vitro cells immersed in 0.5% and 1.0% concentration. Again, stupidly high concentrations. (Remember how much alcohol you have to drink to get your BAC to 0.08%? 6 times that would be how much DMSO solution you’d have to directly drink to get to 0.5%. A bit different from “eating asparagus”, eh?).
Of course, those are very toxic levels where it’s easy to assess cellular damage. But what about low-dose toxicity? Well, 0.3 ml/kg (of 99.9% pure DMSO) was the lowest dose tested in the study. Note that this is /kg of bodyweight. That means, EVEN IF human toxicity profiles were identical to rat toxicity profiles (in actuality, humans tolerate chemical exposure way better than rats even when accounted for body mass), that would still be equivalent to over 1mg of pure DMSO exposure for an 8 lb baby and 24 mg of exposure for a grown adult. Hardly the fearmongered 4mg DMSO dose that even the article admits, is naively counting total metabolite production of DMSO without taking into account more metabolism or excretion, instead of what really matters in toxicity, the concentration in the body at one time.
So basically, eating 500g of asparagus (that’s a lb of asparagus! I don’t eat that much at a time, do you?) may produce 4mg of total sulfur-containing volatiles of which a small portion may be DMSO, of which a small portion may stay in the body at a time, is being to fearmonger… what, a toxicity study that evaluates rats, not humans, at 0.3ml/kg, or equivalent to 24 mg of exposure, may cause cellular apoptosis above background small enough that it needs to be detected in a rat study? Note the study authors take no mention of food, and instead that the population of concern are children exposed to DMSO “who undergo bone marrow transplantation”.
And finally, the point or implication that asparagus has turned more toxic in recent years because today’s asparagus has potentially turned more neurotoxic from sulfur-containing fertilizer is kind of ridiculous. If the implication is being made that sulfur fertilizer -> sulfur-containing compounds -> DMSO, consider that the knowledge that asparagus leads to foul-smelling sulfur-containing urine was described in as early as 1700s (“asparagus…affects the urine with a foetid smell”, “transforms my chamber-pot into a flask of perfume”, “A few Stems of Asparagus eaten, shall give our Urine a disagreable Odour” http://www.smithsonianmag.com/…/why-asparagus-makes…/).
Shouldn’t urine be more foul-smelling if there were at all a increased concentration of sulfur metabolites?
And that would be a poor understanding of why sulfur-based fertilizers are used. They were only INVENTED because things have refused to grow due to sulfur depletion for a century of agriculture…