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Monday, November 24, 2014

Turkey Virtue

Our Friendsgiving Spread this year included turkey cooked sous vide and skin cooked ala plancha.

This week is the American Thanksgiving celebration, a time of traditional foods, centered around eating turkey. It isn't some simple obsession, the American tradition requires serving a roasted bird whole to be carved at the table as a highlight. Cooking this unwieldy beast in this manner is a biophysical challenge that drives people to ornate lengths, but perhaps the shared adversity serves to bond families and tribes together, albeit in ritual.

Noting the unusually high demand for this meat in this season, Maryn McKenna penned an article on Wired urging people to buy "antibiotic-free turkey" to "slow down drug resistance in health care" (a more accurate phrase than stopping drug resistance). Basically, it highlights the Sharing Antimicrobial Reports for Pediatric Stewardship (SHARPS) pledge to encourage purchasing "turkey raised without routine use of antibiotics"). Notice, however, how the two phrases are so readily interchanged. I've written before how there really is no such thing as "antibiotic-free" meat. That phrase is based on the conceit that antibiotics are only synthetic products added by humans, when in fact wherever microbes interact with each other, they produce antibiotics - some of which we may exploit one day for human use. That's not even considering the fact that the antibiotic classes used in farms overlap in a very minor manner with the clinically relevant types.

What puzzles me, though: why target turkeys? Are turkeys a notable reservoir for incubating clinical antibiotic resistance? McKenna's article links out to a 2013 Consumer Reports article that points to conventionally grown turkey as a "persistent source of antibiotic resistant bacteria". For its claims of testing, this article did not adhere to good scientific reporting: it did not completely document the methodology for the sample collection and testing, and lacked controls and proper replication. Most any microbiologist will note in the sloppy nomenclature that the testing design was amateurish. Put into context - finding antibiotic resistant bacteria is actually quite easy, as it predates the development of modern antibiotics. From what I can tell, the writers conflated detection of bacteria post culture with the emergence of antibiotic resistance, and that just serves to confuse the reader. In fact, even birds "raised without antibiotics" yielded significantly antibiotic resistant bacteria — unsurprising, given the survey design.

The SHARPS Tumblr post linked from the article writes: "It has been shown in study after study that use of low-level antibiotics leads to the emergence of resistant bacteria." Both of these studies were done in cattle, and in the second study, the type of diet fed to the animals correlated more strongly to the emergence of antibiotic resistance traits than the use of antibiotics.

An investigation last year (about the same time this sloppy Consumer Report article was published) by NPR's The Salt couldn't find specific data on antibiotic use in raising turkey as the industry doesn't track this information.

So, I remain unconvinced how pledging to buy birds that are specifically labelled "antibiotic-free" or "raised without routine antibiotic use" is going to help impede the evolution of clinically relevant antibiotic resistance traits. But what this will do is create a virtuous halo around producers that label their turkeys in this manner - but how do you know what was turkey labeled as "raised without routine antibiotic use" was indeed raised so? Is there an enforcing body? Not to start a conspiracy theory but where there's a profit motive, fraud becomes tempting. And instead of raising awareness of this complicated topic (which requires a good understanding of evolutionary theory), people will compartmentalize it into virtuous fads.

Thursday, November 13, 2014

Tastes like oysters

The other night, over a bowl of menudo, we had a discussion about "shocking" foods. While some immediately drew the line at even trying tripe, at least one person boasted about trying lutefisk, balut, and century eggs. These exotica aren't really all that wild - certainly balut and century eggs are readily available in the Asian megamalls here in Houston. What intrigues me to get is the elusive tamilok or edible shipworm.

Wood ravaged by shipworms, from Wikimedia Commons
Sometimes referred to as the "termites of the sea" - shipworms burrow their way into wood, and are seen as a pest to the shipping industry. Numerous species abound in the oceans, but the edible shipworm, the tamilok, is found in mangrove trees in Palawan, the Philippines (I've seen unsubstantiated references that the name comes from the English "Tommy, look!", but i can't confirm the etymology), and is often served in kilawin ("cooked" in vinegar). It's often described as tasting vaguely of oysters - although the addition of so many strong flavors may mask it. That's not so unusual because, well, the shipworm isn't a worm at all. It's actually a bivalve mollusc, like an oyster or a clam.

Now, how a shipworm lives on wood as its diet actually depends on the microorganisms it harbors in its gills - much like a termite relies upon symbiotic bacteria in its gut to digest the wood it consumes. Wood, believe it or not, is mostly a carbohydrate called cellulose, and unlike starch, isn't so easily digested into sugars. Various types of cellulose, from paper to switch grass, represent stores of locked up energy, and the biofuel industry seeks out cellulases for industrial production of ethanol from cellulose rather than starch. And shipworms carry a different set of bacteria for it's cellulosic diet, representing a potentially valuable trove of tools to fuel the ship, even if the mollusc itself dines on the hull.

Monday, November 3, 2014

Finding a sugar conspiracy

In a recent piece on HBO, humorist John Oliver painted a scare tactic about how the "sugar industry" is ducking their responsibility for injecting so much sugar into the (unwilling?) American public. Though I usually chuckle along with John Oliver's rants, this one fails on the fact scale by sheer poor understanding of what sugar actually is.

So, let's start there - what is sugar? For most people, that term refers to the sweet crystalline stuff that comes from sugar cane or beets, used to cooking applications. But chemically, sugars are a catchall phrase for simple carbohydrates. You can hook sugars up into larger molecules, and when they get big enough, we start referring to them as starches (if digestible), or fiber (if indigestible). But break down this big molecules - and we get sugars again. The sugar most people are accustomed to dealing with directly is chemically called sucrose - we use such terms in science to be precise, and to avoid the confusion that happens when the same word is used to refer to different things.

And that is exactly the kind of confusion that John Oliver falls into when discussing Clamato. The label he points out (around 2:50) indicates Sugars 11g which he gleefully interprets to mean that the makers add 11 g of sucrose per serving. Notice the difference in reference? That plural form means a measurement of simple carbohydrates in the product, which does not necessarily mean it was sugar added to it. Let's look at one of those labels more closely.

This is a label from a popular apple juice brand known to have no added sugar. Notice that the sugars line is under Total Carbohydrates. That's because collectively, sugars are a type of carbohydrate - this section breaks down that out of the 34 g of measurable carbohydrates, 31g are classifiable as simple enough to be sugars. That could of fructose, glucose, maltose - and yes, even sucrose, but does not mean that 31 g of sucrose were mixed in. The underlying assumption with a lot of these politically charged food issues is a naturalistic fallacy that unless one adds sucrose to an item, it's free of sugars. And metabolically speaking, there's no good reason to go further than this - these simple carbohydrates are digested similarly, and this is the most useful measure. It is actually far more accurate - since it reports the total sugars content via direct analysis. Note, complex carbohydrates can break down into sugars during processing. 

The actual boondoggle here is the FDA proposal to require a further breakdown for "added sugar". The only basis for doing this is the naturalistic fallacy again - as if the intrinsic sugars content of the other ingredients (like apples, tomatoes, and yes, even clams) is chemically different from the added sucrose. The number currently reported for sugars already includes any added sugar (sucrose or otherwise). One cannot separate out the added sugar component via chemical analysis of the product - to get this number, the producer has to track the pipeline and account for this. The FDA then has to implement an audit system to ensure that this accounting is accurate and adds up. This does not replace the chemical analysis in the end - which still has to report the total sugars and other components in the food item. Of course the industry is going to fight this; it is a costly requirement that has dubious benefits for either consumer or producer. 

Instead of understanding the science, Oliver simply plays the easy card of big business taking advantage of the hapless American consumer. With a soundbite from Eric Stice, boom - sugar is cocaine. His example of a scientist is one James Rippe - a doctor heavily vested in "lifestyle medicine". At least understand what a scientist does. His staff casually interleaves sugary drinks consumption into the argument - a Gish galloping bouncing of topics to build  an entertaining, but ultimately fallacious case for this labeling initiative. If there is indeed some kind of sugar conspiracy - I see more evidence of an entertainer trying to spin a tale than an investigator uncovering facts. 

So, please stop forwarding this video on as if it validates anything. It simply preys on a basic lack of understanding of chemistry.