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Thursday, June 26, 2014

Not all white bread are equal

I respect Scientific American as an science communication institution - over they decades, they've evolved from the classic magazine to the myriad online avenues, from blogs to Twitter and podcasts. But I fear that in the zest to embrace the age of the soundbite, some of the care may be slipping. A recent 60-second podcast by Karen Hopkin reports on the potential "health benefits" of white bread. Most of these snappy one-offs are really a populist summarization of the results of a recent academic publication - in general, I approve of this, as the culture of scientific publication still favors dense writing that requires specialization just to read. However, simplification should not happen at the expense of accuracy.

Yes, this is white bread.
The report is about the unexpected association of Lactobacillus (a "healthy" marker in the microbiome) with the consumption of white bread, so it prominently begins with the mention of Wonder Bread. This, of course, is a byproduct of the America-centric nature of the target audience, to whom white bread is synonymous with Wonder Bread. But the study was conducted in Spain, and white bread in Europe is markedly different from the ubiquitous "glutenous slab".

So, how was the study conducted? The authors selected 27 female and 11 male volunteers, aged 56-67 years old, and asked them about what they recalled eating from a selection of 160 items within the past year. After the interview, they collected one stool sample, and analyzed it for DNA. It isn't just any 38 healthy individuals - the data is based on the recollection of middle-aged to older volunteers (heavily skewed to women) from their diets a full year prior, and the stool sample came from one time point.

Though not explicitly stated, the misled hordes of the internet now parrot the line about how white bread (somehow equivocating to Wonder Bread) can be a healthy item. But it is a correlation, and at best a promising line of research. But I am dismayed that science journalism tends to lean towards this need to sell a particular story frame, toying with the very edges of veracity, often misleading lay readers to the wrong conclusion, by selectively glossing over details, or (as in this case) introducing "facts" that weren't in the original paper to begin with. I cannot call this outright lying, but its effects can be more insidious. In the name of "spicing up" a story, a writer can pretty invert the conclusions of a study or report, manipulating the expectations and emotions of the reader. This is a powerful skill, and should be used judiciously.

Tuesday, June 24, 2014

Environmental Impact of "Cultured Meat"

Frog Legs, A Ly, Houston, TX. I'll bet we'll have better luck mass producing tissue cultured frog meat. 
I have previously described my problems with the mainstream media fascination with the "cultured meat" project. But recently, I've been contacted by journalist asking what my opinion is about the published dramatically lower environmental impact from culturing meat as opposed to conventional animal husbandry.The paper cited was published in 2011 by the American Chemical Society's Environmental Science and Technology, authored by Tuomisto and Mattos, claiming a dramatic 45% lower energy use, 96% lower greenhouse gas emissions, and an amazing 96% lower water use. Indeed, this is the paper cited by among its FAQs as a key advantage for tissue cultured meat.

So, let's see what the paper reports. Since a cultured meat production industry doesn't really exist, the paper is basically a fairly complex thought experiment. It presumes the existence of such an industry, and compares it to current beef, sheep, pork and poultry production. This is a vaporware comparison - the authors could assign all sorts of properties to the hypothetical cultured meat production, and we cannot contest it. But if we assign time to when such a pipeline would exist, the evolution of conventional meat production would have also improved in efficiency. In the end, though, this paper does not such prove anything, nor does it actually lead to testable hypotheses. In a sense, it isn't really falsifiable, and makes for poor science.

But such a thought experiment begins with a number of assumptions - and did the authors make reasonable assumptions? Aside from the laughable comparison of value since a number of products come from whole animals other than mincemeat, while culture vats will only make meat, there's the near magical creation of new technology. From the abstract:

Cyanobacteria hydrolysate was assumed to be used as the nutrient and energy source for muscle cell growth.
This is already a problem. Under no circumstance have we proven that conventional animal meat tissue can be grown using cyanobacteria hydrolysate, that raw proteins can be pumped onto cultured muscle cells and they'll metabolize it. Either the authors are ignorant of basic biology of isolated animal cells, interchanging them with yeast cells, or have conveniently cherry picked past this fundamental point. Moreover, the authors write:

The production of growth factors and vitamins are not included in the study as the quantities needed are small (under 0.1% of the DM weight of the media), and therefore the environmental impacts are negligible.
This is a grossly incorrect assumption to make. Despite the lower per weight composition of these micronutrients and growth factors, they are essential and difficult to isolate and synthesize. We have no substitute at the moment for using fetal bovine serum at the moment specifically because this fact. The cells will not grow without these growth factors, one cannot gloss over the environmental impact of harvesting and isolating this material. It's like ignoring the environmental impact of diamonds because they are so small - when in fact mountains can be destroyed to get them.

So, let's do a little background research. This press release from Oxford University (Hanna Tuomisto, the lead author, was a PhD student there at the time) hides a small note at the end: the research was funded by New Harvest, a nonprofit dedicated to cultured meat production. On the border, I would think of this as a conflict of interest. After all, it's a vaporware review that has been used in the last 3 years to claim advantages with regards to environmental impact, but it stands on fantastical unproven promises.

Thursday, June 5, 2014

Fructose alarm?

I came across an article on the science blogging site Science 2.0 stating that soda and juice companies are lying about fructose levels (that's pretty much the headline). It is a parsed summary of an accepted manuscript for the journal Nutrition which analyzes the fructose content of popular packaged beverages made with and without high fructose corn syrup. The article is critical enough to note that the fructose to metabolic syndrome connection is at best tenuous (and a poor approximation of real diets), but the charge that manufacturers are intentionally misleading customers with regards to fructose is bothersome.

To make the charge that someone is lying (or in this case, whole cadres of manufacturers - which only eggs on conspiracy theorists) is a fairly serious interpretation of the case. Does the evidence support this? The authors of the paper purchased samples of the different drinks, and analyzed them with various methods to measure the sugar composition of each sample. A bit of introductory chemistry here: glucose and fructose are simple sugars - when combined, the form sucrose, what we all call table sugar. More importantly, glucose and fructose are isomers - basically, they use the same atoms, but are just arranged differently. In fact, one can convert glucose to fructose and vice versa through a process called isomerization.

Corn syrup is mostly glucose. High fructose corn syrup (HFCS) is made by isomerizing part of that glucose into fructose - in fact, what makes HFCS "high fructose" is usually just 55% fructose to 45% glucose, rather than the 50-50 mix in regular table sugar. There are different grades of HFCS, depending on the amount of fructose therein.

So, the authors claimed that a significant portion of the sodas supposedly made with sucrose still contained free fructose, and that for a good portion of the sodas made with HFCS, the fructose was proportionally higher than the 55% that should be in the food grade HFCS. Does the data bear this out? Fortunately, the paper included the raw data, and I replotted it (after discovering a minor summation mistake in it).

Red circles denote drinks made with sucrose, blue are drinks made with HFCS. 
First of all, they only sample 4 drinks with sucrose. The drink types vary widely in flavor and formulation, but most cluster around the 55% mark - even those made with sucrose. But we also know that sucrose degrades into the simple sugars simply by heating it into syrup - so the fructose content could easily be a byproduct of the processing. The paper actually takes this possibility into consideration - but quickly discards it as unlikely, without reference and any further explanation. Reviewers should have picked up on this contention.

This does lend credence to the idea that by the time it gets to market, HFCS and sucrose are functionally identical. There is the one outlier - the Sierra Mist Natural which seems to retain much undegraded sucrose. It could be something peculiar with that manufacturer: seems to me that there is reasonable doubt here contend that the manufacturers that claim to use sucrose are actually secretly substituting HFCS just based on this evidence alone.

The other is that the drinks are higher than 55% proportion of fructose - a reasonable number of them are also below this magic 55% mark. This is within statistical deviation, and could be explained by simple manufacturing variation or even storage isomerization. But even if they are consistently higher than 55% - I don't think the drinks are labeled to disclose that they are at most 55% fructose. Only that they are made with HFCS - which they do disclose. After all, even at 75% fructose - it would still be called HFCS.

How does this support the contention that there is "lying" going on? This is a potentially libelous situation, as none of this supports evidence of the intent to mislead, or failure to disclose. At best, there is a hint that a manufacturer may be taking shortcuts, but it won't be from this kind of analysis.

Words such as "lying" carry weight. I should hope that science reporting will be more analytical, rather than parroting the frame that the authors of the study wish inject, to bring some kind of ominous implication of conspiracy based on flimsy evidence.