Wednesday, March 19, 2014

The Nutrition Debate #193: “We never changed our mind,” he said.

A recent story in the Los Angeles Times headlined, “High-protein diets: Bad for the middle-aged, good for the elderly.” The last sentence of the piece concludes, “But over 20 years of research linking heavy protein consumption to diseases of aging, eventually to higher IGF-1 levels, he said, ‘we never changed our mind’: Americans’ protein-packed diets ‘are hurting them in a major way.’” This “research” is just another example of “sort-of-science,” an aphorism I attribute to Gary Taubes, and adroitly used in his recent New York Times op-ed described in more detail in The Nutrition Debate #192.

The reporter, Melissa Healy, and the journal Cell Metabolism, where the “research” originally appeared, are also complicit in this “sort-of-science.” Quoting from The Nutrition Debate #192 (and the Taubes’ op-ed):

“The scientific method requires that a hypothesis be rigorously tested, with a skeptical bias, and then ‘the proof’ replicated. Such clinical trials to ‘prove’ that dietary fat caused heart disease, were necessary, scientists acknowledged, but could not be undertaken, for reasons he gives. ‘Since then,’ Taubes wrote, ‘advice to restrict fat and avoid saturated fat has been based on supposition about what would have happened had such trials been done, not on the trials themselves.’

Taubes continues, ‘Nutritionists have adjusted to this reality by accepting a lower standard of evidence on what they’ll believe to be true. One lesson of science, though, is that if the best you can do isn’t good enough to establish reliable knowledge, first acknowledge it – relentless honesty about what can and cannot be extrapolated from data is another core principle of science – and then do more, or do something else. We have a field of sort-of-science in which hypotheses are treated as facts because they’re too hard or expensive to test.’ (Emphasis mine.)

The problem with this “research,” in general is that it is from a “large-population study” (“20 years of research”) and the findings are all “supposition about what would have happened” if a randomized controlled trial of the subject population had been done. The evidence of this is clear to the discerning reader, as I will illustrate shortly. Quoting from #192 again:

This “research is of the kind called “observational studies,” wherein what the researchers do is “observe populations for decades, document what people eat and what illnesses beset them, and then assume that the associations they observe between diet and disease are indeed causal,” to quote Taubes again from his NYT op-ed. Taubes continues: “– that if people who eat copious vegetables, for instance, live longer than those who don’t, it’s the vegetables that cause the effect of a longer life. And maybe they do, but there’s no way to know without experimental trials to test the hypothesis.”

The associations that emerge from these studies used to be known as “hypothesis generating data,’ based on the fact that an association tells us only that two things changed together in time, not that one caused the other. So associations generate hypotheses of causality that then have to be tested. But this hypothesis-generating caveat has been dropped over the years as researchers studying nutrition have decided that this is the best that they can do,” Taubes concludes kindly.

I would not be so kind. I would conclude, cynically, that the “scientists” (and the reporters, et. al.) have another agenda: in this case, to push a plant-based diet. In the LATimes piece it is patently transparent: “But the source of the protein mattered a great deal: for those whose sources of protein were heavily plant-based, nuts and legumes – the increased risk of dying of cancer declined and the increased risk of all-cause mortality disappeared altogether.”

The reporter, in case you wondered about her objectivity, further extends the “associations” of the researcher’s “sort-of-science,” piling on with this “observation”: “The findings of Longo’s team are in line with mounting research on the hazards of heavy consumption of red meats and the protective effects of plant-based nutrients.” Could she be a vegan?

To illustrate the language of “supposition,” here are some “key words” from this piece: “appears to be,” “more likely,” “less likely,” “coaxed the researchers,” “clues outside the lab,” “linked to” “tended to,” “are in line with,” “comparable to,” “promoted,” “common to,” and the granddaddy of them all, “associated with.” The “links” are to dire comparisons and outcomes: “the effect of smoking cigarettes,” “rapid cancerous growth, “increased risk of death,” and “all-cause mortality.”

So, where does all this agenda-based science lead us? To confusion, for the uninitiated, which is most of the health news- consuming public. Advocacy science is not science at all. Studies of hypothesis-generating data produce more hypotheses, as they should, Taubes says. But the public suffers, asking the perennial question, “Whom am I to believe?” For me, when I browse the science news and journal articles, and digests of so-called science designed for the medical profession, I take all such observational studies with a heavy dose of salt (which I like anyway). Increasingly, I tend to not even bother reading them. I might skim an abstract here and there, but, in doing it, I’m acquiring better and better speed-reading skills.

I myself, obviously, am also an advocate, and I too have a bias. I have to wonder how Gary Taubes maintains his objectivity, given that he also admits to a bias. He concludes in his NYT op-ed that “most of us are surely eating too much of something (My vote is sugars and refined grains; we all have our biases).” But I suspect that he is being a bit disingenuous, (or well edited by the NYT). Somehow he manages to have it both ways at the end of his piece: “Making inroads against obesity and diabetes on a population level requires that we know how to treat and prevent it on an individual level.” That’s his pitch to individual readers, guided by hubris and his own just-stated bias? Then to scientists he says, “We’re going to have to stop believing we know the answer, and challenge ourselves to come up with trials that do a better job of testing our beliefs.” In other words, leaving your mind open, rather than “never changing” it. I’m doing my best to keep an open mind.

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