June 3, 2016

Value-added?

From Stuff

Kiwi researchers have come up with a solution to the global obesity epidemic – a bitter plant extract that suppresses appetite.

As you’d expect, calling it “a solution” is completely over the top at the moment. They’ve done a placebo-controlled trial, but lasting less than one day, in only 20 men. The press release is more detailed and more restrained.

What made me mention this story, though, is the numbers. From Stuff

The researchers found that the Amarasate extract stimulated significant increases in hormones that regulate appetite and reduced food intake from 911 kJ (218 calories) to 944 kJ (226 calories).

That sounds incredibly unimpressive: an 8 calorie reduction. It’s wrong, or at least the press release is different and more plausible

.. both gastric and duodenal delivery of the Amarasate™ extract stimulated significant increases in the gut peptide hormones CCK, GLP-1 and PYY while significantly reducing total (lunch plus snack) ad libitum meal energy intake by 911 kJ (218 calories) and 944 kJ (226 calories), respectively.

They looked at two capsules to control where in the gut the stuff was released, and both types reduced calorie intake by a bit more than 200 calories, compared to placebo. The story was off by a factor of 25 or so.

 

 

[update: Those of you who read more carefully than either me or the journalist will have noticed that “reduced .. from 911 kJ .. to 944 kJ ” in the Stuff story is actually an increase, and even less excusable]

[Update next day: The numbers have been fixed —“reduced food intake by up to 944 kJ (226 calories).”  — but not the opening claim. ]

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Thomas Lumley (@tslumley) is Professor of Biostatistics at the University of Auckland. His research interests include semiparametric models, survey sampling, statistical computing, foundations of statistics, and whatever methodological problems his medical collaborators come up with. He also blogs at Biased and Inefficient See all posts by Thomas Lumley »

Comments

  • avatar
    Mike Shaw

    As Communications Manager for Plant & Food Research, thanks for pointing people to the original release. This is yet another example of media doing everything they can to simplify things and not taking the time to properly understand the science first.

    8 years ago

    • avatar
      Thomas Lumley

      The other aspect the story largely missed that I think would have made a nice hook is that the bitter taste receptors being targeted *aren’t* in the mouth.

      8 years ago

  • avatar
    David Welch

    Isn’t it just a case of poor writing?

    I read “reduced food intake from 911 kJ (218 calories) to 944 kJ (226 calories)” as meaning “reduced food intake by between 911 kJ (218 calories) and 944 kJ (226 calories).” Which is pretty much what the press release says.

    8 years ago

    • avatar
      Thomas Lumley

      It isn’t the same: the numbers are averages, so the 20 actual reductions would have had a wider range.

      The press release doesn’t say ‘average’, but I think it’s pretty clearly implied by having two treatments and two numbers. The Stuff story doesn’t say there were two treatments, so even interpreted that way it sounds like an actual range in the data.

      8 years ago