The closer a critic is to the cause they critique, the more treacherous and disloyal their criticisms are perceived to be. This general (though not universal) truth means I fear I am losing my friends in the organic movement more quickly than recent Conservative prime ministers have lost cabinet members. I am not yet a persona non grata at the Soil Association, the UK’s leading organic organisation, but I am surely now one of its least popular paid-up members.
It started with an article in the Guardian in which I highlighted the futility of pursuing organics as the model for the future of agriculture. Although I was at pains to heap praise on what organics did well, this was not enough for true believers, for whom organics remains the pure, gold standard.
The piece led to me being invited to take part in a televised debate for the French Arte TV channel (yet to be broadcast). In it, several people casually mentioned the supposed health benefits of an organic diet and I felt obliged to point out that such claims lack evidence.
Sarah Compson, Associate Director for Standards Innovation at the Soil Association, strongly rejected my claim. I am not sure what exact phrase I used, but if said there was no evidence at all to support its health claims, that would have been wrong. But had I said more precisely that there is insufficient quality evidence to substantiate them, I still believe I would have been right. Compson subsequently provided me with several links to studies pointing to organic food’s health benefits, none of which has changed my mind.
Before I go any further, you might ask why I, someone with no expertise in health and nutrition, is so confident about this. The short answer is that precisely because I have no expertise in health and nutrition, I don’t need to trust my own judgement. All I need is to have an understanding of how to interpret the evidence provided by people who do have the expertise. This is a general critical thinking skill and as someone who has spent a lifetime doing philosophy, I should have it. (Although far from all who should do.)
Principle one is summed up in Hume’s wonderful maxim, “A weaker evidence can never destroy a stronger.” In any debate, there is usually evidence on both sides. The question is, which set of evidence is stronger? In this case, you can always find individual studies which make the claims you are looking for. The question to ask is: if we add up all the good evidence, on which side does it weigh most heavily? And unless you are an organics advocate, the answer is that the weight of evidence does not support claims of organic’s support healthiness. To point to specific studies that say otherwise misses this point.
To make that all-things-considered judgement you have to defer to the verdicts of people who know more than you, and these people disagree among themselves. But when it is clear that the only people claiming the evidence supporting the organic case are the minority already committed to organics, it’s not difficult to account for that disagreement.
However, it is not just a matter of the quantity of evidence but the quality. So it is worth spending some time looking at the apparently better studies supporting the organic case. But note you can’t look at every one. In so many debates, if you want to decisively quash every claim you will spend your life playing intellectual whack-a-mole. You deal with one only to be asked “what about…” and pointed to another. “Whataboutism” is the road to madness. At some point, you have to conclude that the precedents and patterns are clear enough. You would need a clear reason to think that any new piece of evidence was significantly different from others to merit examining it in detail.
There are several reasons why I am comfortable ignoring the “what about” challenge when it comes to organics. The health claims are of two kinds: for the superior nutritional profile of organic foods and for the health risks of non-organic foods, due to chemical residues. Studies can be wheeled out supporting both sets of claims. But time and again, even the apparently good ones can, on closer examination, be ignored because of two factors: effect size and disaggregation.
Take effect size first. There is very good evidence that food coming out of the intensive industrial system is less micronutritionally dense than organic alternatives, meaning it has fewer vitamins and minerals per gram. One of the most striking examples is milk and dairy, which has significantly more omega-3 fatty acids when it is organic.
However, we have to ask what “significantly” means here. The differences are statistically significant, meaning that it is very unlikely the results are the product of chance. But that does not mean they are nutritionally significant. Milk and diary aren’t the main sources of omega-3s in our diet, so getting slightly more from them isn’t going to impact on your health. As one report concluded, “Organic milk, and probably also meat, have an approximately 50 % higher content of omega-3 fatty acids compared to conventional products. However, as these products only are a minor source of omega-3 fatty acids in the average diet, the nutritional significance of this effect is probably low.”
No reputable nutritionist would claim that a person easting a healthy, balanced diet of non-organic food would suffer any micronutrient deficiencies. The amount of fresh fruit, vegetables and wholegrains you eat matters infinitely more than whether they are organic or not. An organic curry followed by a slice of organic carrot cake is worse for you health than a non-organic curry followed by a non-organic apple. Highly processed organic vegan burgers are also worse for you than less processed non-organic meals.
Even the meagre nutritional advantages vanish if you properly disaggregate the data. Most studies make a simple distinction between organic and non-organic. But of course there are many more dimensions to agriculture than this. We need to disaggregate: divide up categories that have been lumped together.
This works most clearly with the dairy example. Why do organic cows have more omega-3s in their milk? Because they are mostly pasture-fed, not raised in feedlots on imported soy beans. But organic cows are not the only ones to be pasture-fed. So the key determinant here isn’t whether a cow is raised organically or not, it’s whether they’re raised on pasture or not.
Debates about nutritional content, however, carry less weight with consumers than fears of being poisoned by nasty chemicals. Here, disaggregation is even more important. If chemical residues pose a risk to health, then what matters is how heavy those residues are. In this, not all farming is equal. Some farmers apply pesticides moderately and with care, others spray them willy-nilly. Some fruits and vegetables retain very little or no residues by the time they come to the table, others, such as leafy greens, retain more.
So even if there is some evidence of unhealthy residues in some non-organic food, it does not follow that organic food is better for you. It merely follows that food with lower or zero levels of residues are better for you, and organics is just one subset of that.
You might think that knowing organics uses no nasty chemical at all means that it is prudent to stick with that, rather than risk ingesting toxins. But this is where effect size comes in again. The regulations controlling pesticide residues are very tight indeed. Their levels have to be much lower than naturally occurring toxins, which are commonplace in food. I was struck by this claim in John Krebs’s Food: A Very Short Introduction: “Potatoes … would probably be banned if they were subject to the same scrutiny [as synthetic food additives] because they contain poisons called glycoalkaloids at levels far higher than the 100th of the ‘no observable effect’ level.”
Even if organic food carries less pesticide risks, it comes with its own, different ones. Organically grown lettuces, for example, are more likely to be fertilised with animals manures which means they are more like to be infected with bugs like E. coli and salmonella. (Salad is a surprisingly common source of food poisoning. A dodgy one in Slovenia made my partner vomit for days.) In Denmark recently, organic egg yolks were found to contain the environmental contaminant PFAS which were absent in non-organic ones. The reason was that the organic hens were fed on fishmeal – which is not what you’d probably expect the diet of organic hens to be.
The key point is that there is no such thing as risk-free eating. To shun one food because of a tiny risk is pointless, because there will be tiny risks in what you eat instead. Effect size matters because otherwise all food will scare you. Think of the cyanide in almonds and carcinogens in toast.
Of all the evidence Sarah Compson sent me, the most challenging was a study conducted for the EU which suggested that despite tight regulation, “epidemiological studies provide evidence of adverse effects” on “cognitive development during childhood” due to “organophosphate insecticide exposure during pregnancy”.
This is concerning but even this does not show organic food is significantly healthier. One problem is that epidemiological studies struggle to disentangle correlation and causation. On study cited in the report, for example, which looked at 28,000 pregnant Norwegian women, suggested that those who ate most organic food saw a 21 % reduction in the risk of pre-eclampsia in the children. But “as no urine or blood samples were analysed, there was no biomonitoring of pesticide exposure in these studies.” In other words other factors may have been at play and since mothers who ate more organic food were on average likely to be more affluent and educated, these could have been significant. Also note that as 21% reduction sounds a lot but pre-eclampsia is already quite rare. A large decrease in a tiny risk affects fewer people than small decrease in a large risk.
The main issue, however, again relates to effect size. Epidemiological studies often reveal effects that are worth addressing at a society level but which are too small at the personal level to warrant any lifestyle change. Take the connection between all-cause mortality and body mass index (BMI). This is a typical graph of how it looks, from a British Medical Journal study. Note that the graph starts to rise around 25. This means that a population level, every increase in BMI from this point means significantly more deaths. But for any given individual, increased risk is initially tiny. For example, the relative risk of death for all cases at BMI of 25 was 0.97 and at 27.5 was 0.98, a difference of 0.01. That’s small enough for any stress involved in shedding a few kilos to more than wipe out any benefits. The change in relative risk between a BMI of 30 and 32.5, in contrast was 0.1, ten times bigger.
Going back to the effects of organophosphate insecticide exposure during pregnancy, a careful read of the report actually shows that the finding is far from clear-cut anyway. The report is a meta-study, collating results from other studies. Some reviews showed no correlation, no study established a direct cause, and “animal studies only show adverse effects at 1,000-fold higher exposures”.
Still, even if on a precautionary principle we accept the claim, what should follow? Not that we should all eat organic food. The report suggests “population groups at high risk, such as pregnant women and children, could minimise their exposures by avoiding the kinds of conventional fruits and vegetables that show the highest residue levels.” In other words, some people might be advised to avoid some foods. Most individuals would get no health benefits at all from doing so. In addition, the key action would be to reduce harmful residues in these foods, not avoid pesticides altogether.
I think this takes us to the nub of the issue. The reason we should be grateful the organic movement exists is that for years it has been shining a spotlight on the problems with intensive industrial agriculture. For consumers unable to work out where exactly their food comes from, it provides reassurance of good (if not always best) sustainability and animal welfare practice – if you can afford it.
However, the key distinctions, both for health and the environment, are not between organic and non-organic. It just isn’t true that organic food always has a significantly better nutritionally profile or that non-organic food is routinely toxic. When such claims are made they reinforce an unhelpful binary in the public consciousness in which organic is good, non-organic is bad.
So I stand by the claim that there is insufficient good evidence to say that organic food is better for our health. But I will add that the existence of the organic movement is good for our wider health, because it is leading the fight against the worst forms of farming practices that threaten our environment. And I will continue to be a member of the Soil Association. We all need criticism, and it is best when it comes from friends.
(In my most recent members’ update they ask me if I’ll help recruit new members! Sure. Join from just £5 a month today and get a free packet of organic vegetable seeds.)
News
I’ve had several pieces published over the last fortnight. The most significant from my point of view is my essay for Aeon provoked by having our cat euthanised. Our relationship with other animals is complicated and in this piece I try to bring some clarity without over-simplifying.
Just out today: Think yourself better: 10 rules of philosophy to live by, in the Guardian. (Silly headline, not mine.)
I reviewed Living for Pleasure: an Epicurean guide to life by Emily A Austin in the Guardian. Digested read: a good hangover cure for anyone drunk on stoicism.
This month’s philosopher-at-large column for Prospect is on the meanings of equality.
I was briefly on Radio Four’s PM programme the other day and for longer on BBC radio Scotland’s Sunday
The rest of my news is about upcoming things I mentioned last time, so please skip ahead if you’ve heard this before…
My latest book, How to Think Like a Philosopher, is now ready to pre-order. Independent bookseller Max Minerva’s Marvellous Books can send the book post-free to the UK, signed and with a personal dedication request from me on request, and you’ll also get a free fridge magnet. There is extra postage to pay if you’re outside the UK but if you are a supporter, that’s free too. I shouldn’t point this out, but it’s worth becoming one just for a month and then canceling for this benefit alone. You can also browse though the many exclusive articles, podcasts and videos and download them. (Times are hard, many of you have to economise!)
I can’t afford not to shout about the fantastic endorsements I’ve got for the book, so this week let me share Gavin Esler’s: “Another brilliant, engaging and highly readable account by Julian Baggini… Simply superb.”
I’m hosting a Bristol Ideas event around the book’s themes at St George’s Bristol on Wednesday 22 February. I’ll be joined by Lisa Bortolotti and Rebecca Buxton to discuss the keys to better thinking. It’ll be a relaxed “salon” format”, with 45 minutes of discussion with the panel, a short break to get a drink, and 45-minutes of discussion led by audience questions. Tickets are on sale now.
I’m also talking about the book at the Bath Royal Literary and Scientific Institution on Tuesday 7 March.
That’s it for now. No “on my radar” section this fortnight because I’ve already used up all my available time own the longer than usual main content.
Until next time, if nothing prevents, thanks for your interest.