All Those Healthy Eating “Rules” are Just Guesses, Really

File this under “Who Even Knows, Anymore?”

s.e. smith recently posted a photo of a “5 a day” tag that came on some asparagus she bought. She felt, and I agree, that those tags are a form of food policing – instructing people what they “should” eat. The corollary, of course, is that if people do not follow these food guidelines, their unhealthiness is their own fault.  s.e. explored some of the problems with these educational campaigns over at This Ain’t Living, but I want to highlight another problem here.

That problem being, namely, that NOBODY KNOWS WHAT THEY ARE TALKING ABOUT. From a recent article at Scientific American:

The recommendation that people eat at least five servings (about 400 grams) of fruits and veggies each day, espoused by the WHO since 1990, was based on studies that found a link between higher intakes of these foods and lower risks for cancer and other diseases.

Since the 1990s, however, evidence from large studies has been mounting that the protective effects of these foods against cancer in particular might be modest—if it exists at all.

The results are in line with other findings both in the U.S. and abroad that suggest the protective effect of fruits and vegetables is “much smaller than had been believed 10 years ago,” Harvard School of Public Health’s Walter Willett, who wrote an editorial accompanying the study, noted in an e-mail to People who eat more fresh fruits and vegetables are also more likely to make other healthful lifestyle choices, such as exercising more and drinking and smoking less, which the researchers noted “may have contributed to a lower cancer risk” overall.

So this “5 a day” rule – which has been adopted as healthy eating dogma all over the world – may not actually be based on much of anything and there’s virtually no evidence to support the assertion that eating more fruits and veggies will automatically lead to better health.

But watch – it will still be used to shame people, and to blame them for their own health problems, regardless of the lack of scientific support. This strongly supports the argument that these healthy eating rules, and other rules about what people “should” do to be healthy, are much less about scientifically proven relationships between eating and health and much more about shaming people for their health problems.

(h/t The Awl for the link, and the suggestion that You Are Going To Get Cancer Anyway, So Have The Steak)

13 thoughts on “All Those Healthy Eating “Rules” are Just Guesses, Really

  1. Yes, we don’t know as much about nutrition as is often claimed. But what’s really happening with the five portions is that there is a clearer picture coming out that it has a very significant effect with some cancers (colorectal for example), and no effect on others (pancreatic for example). So overall the effect is less than hyped in the 90s because it was thought that the effect was across all cancers, when it’s more specific to some than others.

    And the much touted ‘smaller effect’ is that ‘only’ 2.5% of cancers will be prevented from eating five a day. That’s ‘only’ around seven thousand people a year in the UK.

    The politics of healthy food, bahaviour policing and poverty interest me greatly and I have a lot of bones to pick with current public health policies in this area. But this study is not what you make it out to be.

  2. It is used to blame people who develop health problems. I once saw a Ph.D.’s website claiming a direct link to sugar intake as a cause for vulvodynia. And there these buttons & stuff on her website that were all like Sugar = Death.

    And I was like, did you read the same research paper I read? I see the citation, so It looks like you did but how did you come to these conclusions? There was like one line in the paper re: some kind of MAYBE indirect link we don’t even know right now.

    I looked around but I did not see any scientific research papers supporting this as a direct link. So it made me upset, because it was like guilting women who develop vulvodynia into thinking that it’s all their own fault because they couldn’t put down the cupcakes or whatever.

    And then like, there’s all these other diets that are suggested for pelvic pain … But I was looking at PubMed the other night & one of the diets is basically debunked. It’s not practical & doesn’t work most of the time. It might work once in awhile but for a lot of folks who try it, it’s just months of denial & not being able to enjoy the food you want to have and doesn’t do anything. I didn’t need to change my diet.
    .-= K´s last blog ..Interesting posts, weekend of 4/10/10 =-.

  3. Studies in recent years have also shown that vitamin intake has no statistically significant effect on cancers and other conditions later in life. The only that did were calcium+D for osteoporosis and another vitamin for prostate cancer. Everything else the effects failed to meet statistical significance.

    And yet the discourse around food holds certain things to be Obviously, Inarguably True, when in fact the scientific evidence behind them are dubious or nonexistence.

    You cannot, in fact, guarantee good health for the length of your life. By doing anything. You can’t guarantee not to obtain conditions of the body or brain by consuming or not consuming certain things/certain ways. You can influence your bodily condition within a certain range… but that range is, for most people, set from childhood, unmodifiable. You can’t eat/not eat/exercise/anything your way into a different range — range of weight, of energy, of sociability, of dexterity — and so on.

    Your body is your body. It cannot be re-drawn, re-built, re-formed. It can be loved, respected, worked with. Or it can be hated, disrespected, adversarial.

    When we make these confident claims about our ability to change who and what we fundamentally are, we help enforce, reinforce, a hierarchical system of bodily valuation, a system in which the most privileged bodies are normalized and any slight differences from them are vilified. We create a culture of shame. What we don’t do is force health. Or even encourage it.

  4. I hate nutrition shaming. And, after seeing five nutritionists in five years, I have come to the conclusion that more than half of them don’t know what the heck they are doing or they have eating problems themselves. Three of those nutritionists admitted they became nutritionists because they had eating disorders- and at least two of them were fairly obviously not over the disorder, based on stories they told me about how they ate. And they were trying to help me over come my own eating disorder. It was frightening.

    I believe that everyone’s body is different. I hate the dogmatic statements like ‘gluten is poison’ or ‘red food dye causes ADD.’ I can’t tell you how many people have told me or my parents over the years that my LDs would be cured if I just ate organic or red-food dye free or only food picked from red dirt or what-have you. The attitude that these ‘sharers’ of information had was less than kind. They basically insinuated that, by not following their advice, my parents were causing my LDs.

    I eat a diet that works for me. I try to avoid people who talk over much about their diet. I wish that it was not a topic screamed from every magazine cover and discussed by with a religious fervor by segmetns of the population. I wish young girls didn’t have to hear it because that often sets the stage for eating disorders.

    Great post.

  5. Some people can’t eat that many fruits and vegetables if they wanted to. I’m pretty sure I’ve got trouble absorbing fructose, but most of the time, I’m fine as long as I watch the quantity of fructose I ingest. (Not always easy since HFCS is the one thing that sets me off for sure. Ug.) Some fruits are better than others, but I have to keep those to a minimum, too. Overdoing it probably won’t kill me but it’s pretty unpleasant and it might just negate most of the benefit I could derive from eating so much fruit. I’m sure somebody out there has it worse than I do, but like me, they probably have some idea what’s good for them and what isn’t and the food police aren’t going to help.

  6. I’ve got to agree with Marge on this one. Your headline is grossly misleading and reminiscent of the worst examples of science reporting in the popular press.

    They didn’t ‘guess’ 10 years ago. They didn’t ‘get it wrong’. The 5-a-day advice was based on the best evidence available at the time. What the article is saying is, ‘We’ve done some more work on this subject, and we might have to revise our advice in the light of the results.’


    Scientific results are not set in stone for all time. They must be constantly re-examined in the light of new evidence. And so must public policy based on that science.

  7. What is so controversial about the word “guess”? That’s exactly what we’re doing, isn’t it? Guessing?

    I don’t understand why it’s so hard to deal with — do people not like admitting the unknown? acknowledging any small area in which we do not have total control?

    I don’t understand the vehemence in response to such a simple suggestion. That what we’re doing is *guessing.* That guessing is *what science does.*

    I think a much healthier (see what I did there?) attitude would be, not, “This is what I’m told, so it is clearly true, and must be followed as a rule,” but, “This is how things seem to be, and I will keep it in mind as I make decisions, but realize that it is nowhere near definite, that change is constant, and that there is no such thing as a guarantee.”

    Really, it’s not that hard.

  8. While I abhor food shaming/policing in any form, I have to agree with Marge and Dogged here. The article you cite only says that fruits and vegetables seem to not be as good at preventing cancer as previously thought. So I think that your statement that “there’s virtually no evidence to support the assertion that eating more fruits and veggies will automatically lead to better health” is an extrapolation that can’t really be made from the evidence given. There are other health benefits from eating fresh produce (especially when compared to eating highly processed foods), preventing cancer just doesn’t seem to be one of them.

    (Of course, people should go out and eat what they want, like, and can access easily and ignore the food police. And most people telling you what you “should” eat are full of shit.)

  9. amandaw – the point I was making was the opposite of the one you suggest. I was saying that science IS largely unknown, that we DON’T have total control, so when we find a new piece of the puzzle, it’s not that the information we had before was wrong, just that we have better information now. We have to adjust our model to take account of the new evidence. But what we must not do is say, ‘this bit of evidence is slightly different from what we found before, so let’s chuck out everything that was based on our previous findings’. Science is incremental. Knowledge is always – and will always be – incomplete.

    However the problem I have with the article’s title, and the later statement that ‘NOBODY KNOWS WHAT THEY ARE TALKING ABOUT’ is that they overstate the case. By saying something is ‘just a guess’, you’re implying it could just as easily be wrong as right. That is not true when the ‘guess’ is based on sound scientific evidence. And to say ‘nobody knows what they are talking about’ is sensationalist and untrue. It demonstrates a fundamental misunderstanding of the scientific method. The model is incomplete – as all models must inevitably be – but discovering after 10 years that the model requires some adjustment is not the same as ‘nobody knowing what they’re talking about’.

  10. KJ: Totally with you on the dogmatic statements. I’m especially aware of it when it comes to weight issues. It [annoys me (redacted per comment policy)], because we never really seem to get much advice of any use on food issues, just “You should eat this this and this, and avoid that and the thing next to it”. Which distracts us from actually trying to eat healthy, towards eating what we’re ‘supposed’ to. So it makes us feel warm and fuzzy to be eating the ‘right’ things, but whether it’s actually doing us any physical good is another matter entirely.

  11. “Guess” is pretty much the right word, to me. An educated guess? Sure. Definition one in my dictionary is “Guess: estimate or suppose (something) without sufficient information to be sure of being correct” – which, yes, is pretty much exactly what this is.

    It clearly triggers strong reactions in some, but that doesn’t mean we shouldn’t critically and strongly examine the way biomedical science is reported in our media, and incorporated into policy. Perhaps it means we should, and more so.

    There are also other reasons, such as environmental reasons, that whole plant foods should be structurally facilitated or at least not actively discouraged as they are in some countries (by which I do NOT mean individual haranguing), but it’s not as though acknowledging uncertainty makes all of this fall apart like a house of cards. That is, unless policy is based on false certainties in the first place.

    I get the feeling that some negative reaction to these sorts of ideas, especially amongst people involved in government and clinical guidelines formulation, may be based in the popular “It’ll give them a LICENCE to eat ANYTHING!” idea. Some old posts at Shapely Prose take this moral panic apart quite niftily, so I won’t attempt to repeat here.

  12. re the scientific method – Dogged and others put it much better than I could have.

    I have a GI illness that is aggravated when I eat traditionally “naughty” foods, and is improved when I eat in ways that are socially/nutritionally condoned. I worked with a person with the same illness who was sick frequently and ate the things I had (after years of suffering) learned to avoid. I never said anything to them about it, figuring it was not my business. It wasn’t a tough choice as we weren’t friends; if it had been someone I cared about, I might have said something in the hopes of sparing them some agony. But am I right in thinking that it’s generally best to say nothing?

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