For some people the definition of science is closely linked to the application of what they call “the scientific method”*; a number of them even fail to notice that the scientific method cannot supplant scientific thinking.

“He [Friedrich Weismann] got a colony of mice, and cut off their tails. Then he waited to see whether their children would be born without tails. They were not, as Butler could have told him beforehand. He then cut off the children’s tails, and waited to see whether the grandchildren would be born with at least rather short tails. They were not, as I could have told him beforehand. So with the patience and industry on which men of science pride themselves, he cut off the grandchildren’s tails too, and waited, full of hope, for the birth of curtailed great-grandchildren. But their tails were quite up to the mark, as any fool could have told him beforehand.” George Bernard Shaw (1)

My attention was drawn recently to an article (2) boldly proclaiming “Our data demonstrate that flies raised on organic food extracts by and large performed better on the majority of health tests”, and even more boldly proclaiming: “Our data suggest that organic foods provide improved health outcomes”. The authors used Drosophila melanogaster (fruit flies) as a model to study the alleged health effects of “organic” food. My opinion was that the experiments described in the paper were carried out rigorously, and I had no reason to mistrust their statistical methods or results. Did I then run to my local “organic-food” shop to stock up? Hardly.

Even if the results were reliable their conclusions were clearly flawed, as anyone knowing that flies are insects, could have told them before hand.

In the discussion of the paper the authors attribute their results (longer lifespan, more descendents, etc.) to the beneficial health effects of “organic” foods; the mechanisms of action -they admit- are yet to be determined. The authors never discuss the deleterious effect that insecticides have on insects or that, what they call “conventional” food is grown with, and probably contains at least traces of, insecticides.

It is worth noticing that the evils of insecticides are brought up several times in the introduction of the paper; their allegedly harmful effects, in humans, are expensively listed there. We are even reminded that metabolites of insecticides can be found in infants**. One may think that insecticides are nastier to humans than to flies. The authors never state that the “conventional” food they have used may contain traces of insecticide. They never measured the levels of insecticide that could be negatively affecting the flies. More importantly: they did not included a control where the same amount of insecticide was added to “organic” food in order to test that, under equal conditions, “organic” foods provide health benefits as compared with “conventional” foods. The authors just assumed that “organic” food improved flies’ health because is more nutritious, not because it does not contain insecticides.

After complaining that long-term meta-studies in humans have always failed to show positive health effects of organic foods (3), the authors finally conclude:

“The use of the Drosophila model will be invaluable not only in investigating potential health effects of a variety of food sources, but furthermore in dissecting the molecular pathways underlying the health effects of organic foods”

I would have concluded differently: using insects to compare foods grown with or without insecticide provides the means to test how good insecticides are in accomplishing their goal: killing pests. For anyone wanting to show that “organic” foods are more nutritious and healthier than “conventional” food, using a mammalian model is advised.

To have a pre-conceived much-fancied idea and to invent an inconsistent system to justify it has been the prerogative of many philosophers; it should not be the vice of scientists. We can fancy many things that are not science, and that’s perfectly fine. I like real ale; I like it because I believe it tastes better, it offers more variety and, I must confess, because of the snobbish pleasure of knowing that something has been specially crafted, taking up considerable time and effort. I will not try to promote it by using scare mongering. I will not say that it is better for human health than mass-produced pasteurized generic lagers neither. I will promote it by using the subjective reasons exposed above or just saying: I believe it tastes better and I can afford to pay the extra money it costs.

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 * TheOxforddictionary defines scientific method as a procedure consisting of systematic observation, measurement, and experiment.

** The fact that modern mass-spectrometers can detect almost negligible levels of whatever someone wants to find is never mentioned.

(1) Back to Methuselah (1921)

(2) Plos One (2013) Vol 8  e52988 (Click here to see the article)

(3) Am J Clin Nutr (2010) vol 92 p 203-210 (Click here to see the article)



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  • Mike Mellor 01/06/2013 at 3:11 pm

    I forgot, the two points I wanted to make in my previous post were that

    1. Organic doesn’t automatically mean healthier and
    2. Organic foods also contain insecticides, so in the test they should have impacted on fly longevity as well. This counters your argument, but as you also remarked, what is fatal to insects may have no effect on mammals.

    • Ariel Poliandri 01/06/2013 at 6:40 pm

      Thanks for your comments Mike,
      The name of Bruce Ames doesn’t ring a bell to me but I may have read some of his papers; there are so many papers out there about carcinogens, endocrine disruptors, etc.
      It is curious that he found so many carcinogens yet after a couple of decades most of us haven’t developed any cancer.
      The main problem with many studies is that the concentrations of potential “carcinogens” tested are ridiculously high; thousands or millions of times higher than the concentrations that can be found in blood. I’ve heard of people proving that sugar is carcinogenic; that is glucose + fructose; these are the main sources of energy for mammalian cells; carcinogenic!
      In any case if the “organic” food used in the study discussed in the post contained insecticides (organic farmers are allowed to use “natural” pesticides), clearly it wouldn’t be the modern pesticides used in “conventional” agriculture and that is what they should have tested.
      As I said, I have nothing against “organic” food but I don’t buy the ridiculous concept that it is healthier. Some time I do buy “organic”; some times I believe it tastes better because of the care that a micro-farmer will put into growing his vegetables and take them FRESH to market. I wouldn’t buy dry pasta prepared with organic flour; that will be pointlessly expensive.

  • Mike Mellor 01/06/2013 at 2:53 pm

    This is a transcript from one of the excellent Richard A. Muller videos “Physics for Future Presidents,” webcasts from his lecture series at UC Berkeley. He’s talking about his friend Bruce Ames, the inventor of the method that I believe is still used today to detect mutagenics:

    I quote:

    People started looking at everything this way [from the point of view of mutagenics], particularly food additives.

    And they discovered to their horror that about one half of all food additives were mutagenic and therefore, possible carcinogens.

    And this became a great scandal about all of these additives that people were putting in that were mutagenic. It was horrible!

    And so Bruce Ames became a hero among the people who wanted to outlaw all these additives.

    And people started going to natural foods.

    Now I went to natural foods when I discovered they were tastier than the stuff I got at the supermarket. Some people switch when they think they’re healthier.

    Now Ames, being a really good scientist, was disturbed by this. He said, “They’re not testing natural foods.” So he started testing natural foods to see what they were.

    He found they were far worse.

    That doesn’t mean, so bad you shouldn’t eat them. I keep on eating them.

    I had Bruce Ames over for dinner and he points out that mushrooms are fifty per cent carcinogens! Can you believe that? Fifty per cent of the mushrooms are carcinogens! That’s huge!

    I gave him mushrooms for dinner and I watch him [mimes eating] “Hmm! These are good mushrooms! Nom nom nom nom!”

    And then when I served him his coffee, he said, “No thanks!”

    So I said, “Why do you eat mushrooms, fifty per cent carcinogens, but not this coffee?”

    And he said, “Well the mushrooms are extremely weak carcinogens, it’s not an either-or, it’s how many mutations do they cause?”

    Now yes, half of the chemicals in mushrooms are carcinogenic, but it’s so mild, it’s almost negligible. It’s like the radiation in my wristwatch, or something.

    When you burn something you make very powerful carcinogens, and so he stayed away from coffee.

    And I don’t. I drink exclusively coffee except when there’s none around then I drink Starbucks and when there’s none around I’ll drink something else.

    But to me the pleasure of the coffee outweighs the tiny risk of cancer.

    But the most interesting thing he found was that the foods that were natural that did not use pesticides were the worst culprits in terms of mutagens.

    Why is that, when you think about it? And then he figured it out. It’s obvious.

    You have a whole bunch of plants here and you don’t spray them with these pesticides. Pesticides, by the way, are tested to be very mild mutagens, so mild that he eats them along with mushrooms. He doesn’t care. All the pesticides that are being used on plants he says are negligible dangers.

    But the people who don’t want to use those, what do they do? They go crop and they find that insects attack this, this, this, this and this, they don’t attack that one there. Ah, that’s the good one!

    And they take that one, and they grow it. And the insects attack, not many of them, but these it really doesn’t attack! And you take those and you grow that and pretty soon you have natural plants.

    And Bruce Ames as a scientist says, “That’s interesting, why is this surviving all the insects?”

    So he takes the plant, chops it up, does his test and sure enough, it is highly mutagenic! It is full of poisons! The insects that attack that one die!

    But this is the natural plant that is naturally resistant to bugs and this is the one that some people choose to eat instead of the one that has the very harmless things, the things that have been tested to kill bugs not humans, sprayed on them.

    My advice to you is, if you eat natural foods, do it because you like the flavour. Don’t do it because you think you’re avoiding the carcinogens. If anything it’s just the opposite.

    :end quote

  • Ariel Poliandri 01/02/2013 at 4:40 pm

    @Diana: Yes, some individual researches may omit proper controls to favour their hypothesis*, which is terrible. In the case of “organic” foods however, is an entire congregation that is always passing over adequate controls.

    * For example: I know of a researcher that used beads-alone, instead of non-immune serum, as a control for co-immunoprecipitations…

  • Diana 01/02/2013 at 1:29 pm

    Brilliant story! Now we should all go beyong finding it educational and try to detect whether it reflects our own attitude when we start an experiment…

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