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Is Organic More Nutritious?
Posted 13th July by Kevin Klatt

A new publication (1) in the British Journal of Nutrition has caused some controversy in the nutrition field, with many on the pro-organic side hailing it as proof that organic food really is better for you. The study is garnering headlines, such as the one on Nature’s blog, that organic is more nutritious.

Part of the reason this has caused some controversy is because very few studies have ever supported a nutritional benefit to consuming organic food. In 2008, a study in the Netherlands found a beneficial effect of organic milk consumption on the incidence of eczema (2). A study in the U.S. found that organic milk contained more omega 3′s, though this is due more to animal feed than whether something is organic or not (the differences were also arguably irrelevant if you compare milk to other foods rich in n-3′s, like flax and fish) (3). Organic tomatoes were also shown to accumulate more vitamin C and phenolic compounds (antioxidants) than conventional tomatoes, while also being smaller (4) – the difference in vitamin C is pretty irrelevant, as achieving the DRI for vitamin C is quite easily done (eat 1 conventional orange). The differences were also expressed as mg/kg, so while the organic tomatoes might contain more per kilogram, they also weigh less.

The majority of research has shown that there is no nutritional difference between consuming organic or conventional foods. A 2009 systematic review (5) by Dangour on the nutrient quality of organic vs conventional food found no significant differences, besides higher nitrogen in conventional foods and higher phosphorus/acidity in organic – the PDF is free and a look at table shows all of the nutrients analyzed. A 2010 review (6), also by Dangour, followed up on the 2009 review and found no specific health benefits in the literature (besides the eczema/dairy association i mentioned above) from consuming organic food. In 2012, the Annals of Internal Medicine published a systematic review (7) on organic vs conventional food and concluded that there are not significant nutrient differences between organic and conventional foods, though organic foods were less likely to be contaminated with bacteria resistant to 3 or more antibiotics.

The known benefits to consuming organic food, from a nutrient standpoint, are pretty non-existent. This new meta-analysis doesn’t change too much about that, despite what headlines are saying. The new meta-analysis finds that organic food, on average, has higher amounts of antioxidants (flavonoids, phenolic acids, anthocyanins, carotenoids, and vitamin C) and lower levels of cadmium. What the headlines aren’t really saying much of is that organic foods also, on average, had less protein, fiber, vitamin E, and nitrates (in the case of vegetables, this is good, as opposed to those found in cured meats). The organic food, as expected, also had lower residues of synthetic pesticides. No measure of organic pesticides was taken (see below for further discussion).

Before we start to break this down, I think it’s pertinent to note that this study included 347 studies – much larger than any other review of organic vs conventional. While this might sound like a good thing, it only takes a quick glance at Table 1 to see that the overall reliability of the analyses was determined to be moderate for most of the differences, and low for many. Only 3 of the effect differences (1 antioxidant test, and flavones and flavonols) had a good reliability. The quality of the data included varies. Variability will be the theme as we explore this meta-analysis.

Expert responses of the study can be found here. Here’s my breakdown:
1. Cadmium – The results of this meta-analysis found that cadmium levels were mainly lower in cereal grains, with very little difference for vegetables. Cadmium intake in the US is, on average, 11.06mcg/day (22) and uptake by plants largely depends on the amount of cadmium present in the soil/growth medium, the soil’s pH, the species of plant, and what part of the plant is being eaten (8). The uptake of cadmium differences seen in this study likely represent differences in Cadmium concentrations in the soil. Eating organically won’t necessarily reduce your cadmium intake, unless you know the soil your organic food was grown in was low in cadmium – a recent study (9) found that those consuming organic wheat ingested slightly more Cadmium than conventional in Belgium, and both were significantly lower than the European Acceptable Tolerable intake of 100mcgs/d. The WHO sets a tolerable monthly intake of 25mcg/kg body weight (10) – US averages, derived from conventional foods primarily, are about 6mcg/kg/month, well within tolerable limits. While the authors of the meta-analysis suggest that reducing Cadmium from all sources is a good idea, this begs the question of whether choosing all organic food is the best way to do so. The EPA (11) doesn’t identify reducing cadmium from food sources as a major concern ( and suggests reducing intake of shellfish, kidney and liver meats if you’re going to focus on food sources). They cite that the level of cadmium in our body from food is .0004mg/kg/day,a level 10x lower than that which causes kidney damage in cases where individuals consume food contaminated with excess cadmium. Cigarette smoking and inhaling cadmium are the larger concerns. Ultimately, Cadmium from cereal grain doesn’t appear to present much of a threat, and the amount of Cadmium in food will depend on the amount in the soil, which varies significantly. This idea of heavy metal toxicity reminds me of a nice article in Slate about heavy metals in organic fertilizers, the need to trash the organic/conventional dichotomy and embrace biotechnology – see here.

2. Global Data – this variation in cadmium speaks to one issue I have with the study’s presentation in the news – how applicable is it to the U.S.? Regarding cadmium levels in the US, the USDA’s National Organic Program leaves it up to farmers to manage their own plants/animals to avoid heavy metal toxicity – so it’ll depend on the individual farm. This meta-analysis looked at data from all over the world – approximately 70% of the studies took place in Europe. The rest took place in the USA, Canada, Brazil and Japan. US consumers using this study to justify buying organic are basing that conclusion off of data from agricultural systems outside the U.S., and from food grown in radically different environments. Take a look at the range in the Confidence Intervals and you’ll see pretty sizable variability in many of the compounds analyzed. The theme of organic vs conventional is that there is much variability between farms (practices, soil quality, weather); you really can’t be sure that what you’re buying reflects global averages.

3. Pesticide differences – much of the concern about buying organic seems to be the fear that conventional foods are sprayed with harmful chemicals. For one, organic is sprayed with chemicals too; according to the most recent Nutrition Reviews publication on this topic (17), about 20 chemicals are used in organic agriculture – the safety of several, including rotenone, Bacillus thuringiensis spores, pyrethrins and sodium fluoride has been questioned. Regarding toxicity of the pesticide residues found in conventional foods, and much of the reason I’m not concerned with dietary exposure at current levels, see the work of Carl Winter (12,26) (exposure to pesticides through non-dietary routes is another, much more important story- see here, and here). For a nice comparison of organic vs conventional pesticide use, and their effects on health and the environment, I encourage you to read this Scientific American article- here, the response here, and the response to the response here . I would love to see more studies looking at the organic pesticide residues and their health effects. My lack of concern about dietary pesticide exposure isn’t to downplay the potential effects of chemicals used in agriculture – we should continually monitor their safety, improve upon our use of them, and ensure their environmental safety, for both organic and conventional chemicals. This persistent notion that organic isn’t sprayed with chemicals that may also be dangerous to humans/environment is absurd. I feel it’s important to also note that, in toxicology, there are several models of toxicity – while many are familiar with the linear models (toxicity increases as dosage does), there is another model known as the hormetic model (essentially, low levels good, high levels bad). As a real world example of hormesis, think of exercise – it induces low levels of oxidative stress that activate the body’s defense systems and adaptation, which lead to health benefits (18, 19). It’s been proposed that low levels of pesticides (as well as antioxidants, which I’ll discuss below) may work in this same way (20,21). I wouldn’t directly apply this thinking to humans until we have further strong data, but it certainly deserves further research, and challenges the way we think about eliminating all sources of ‘toxic’ chemicals.

4.Antioxidants – The antioxidant differences in this study are probably the biggest reason this study has gotten so much press. The differences between organic and conventional are certainly intriguing, though not very surprising. Most compounds we think of as ‘antioxidants’ are actually plant defense compounds. If you reduce the amount of pests in the environment of a plant, it’s not surprising it’d produce fewer defensive molecules.When we say antioxidants, it’s pertinent to note that there are essential ones, like vitamin C and E, and then there are the non-essential ones in the food matrix (flavonoids, and phenolics), whose role science is only beginning to understand. Consumers tend to think of antioxidants as a good thing, largely because epidemiological evidence shows high consumption of fruit/vegetable intake (13), rich in these compounds, protect against a number of causes of mortality. While it’s easy to think “more is better” when we’re talking about antioxidants, it’s important to remember that an optimal intake level has not been determined. It’s a sizable jump to state that consuming more of these compounds will lead to better health outcomes – the fact remains, we have little data to support saying this. I’m skeptical that the differences seen in this meta-analysis would have much effect on health outcomes – the classes of chemicals looked at are quite heterogeneous, but in general, the bioavailability of these non-essential antioxidants is quite low (see here) – while reports stating ‘organic has up to 40% more antioxidants than conventional’ may sound significant, the reality after factoring in bioavailability is likely much less substantial. Most importantly, all of the benefits attributed to consuming foods rich in these non-essential antioxidants come from epidemiological/observational data where individuals were consuming a mix of organic and conventional foods (highly likely that majority was conventional). It’s easy to only look at the positive effects of these compounds, but they do have potentially undesirable roles too e.g. polyphenols have been shown to inhibit iron absorption (15,16). For a good review of antioxidants and cancer, see cancer.gov’s take on the issue – here – in short, we’re far from having enough data to make any general statements specifically about antioxidants and long-term health; consuming some, within normal dietary ranges, is likely beneficial. . The moment there is data to suggest a benefit from consuming the amounts in organic, I will certainly change my opinion. As of now, the ‘best’ data about organic food consumption and cancer that I know of comes from a 9.3yr long study following individuals consuming varying amounts of organic foods (14) – no reduction in the incidence of cancer was seen, except for Non-Hodgkin Lymphoma – this study has a lot of limitation in drawing too many conclusions either way. While we’re talking about cancer, reviews have not supported a role for synthetic pesticides in cancer – see here. If one is really concerned about the antioxidant differences in organic vs conventional produce, I’d suggest a cheaper alternative of consuming a couple cups of brewed green tea per day, an excellent source of polyphenols with well documented health benefits (23,24,25).

As a future clinician, I have yet to see any data (including this meta-analysis) that would lead me to tell individuals to consume organic foods over conventional, from a nutritional standpoint. The increased cost of organic food is certainly something to be weighed into this equation. There is much sentiment revolving around this issue, and while education is important/fear-mongering should be limited, I think it’s important to hear the concerns of individuals surrounding the consumption of non-organic foods, address them as best as possible, and work with patients/clients to achieve a nutritionally adequate diet that they are comfortable consuming.

As a scientist, I see the simplistic dichotomy between ‘organic’ and ‘conventional’ as highly problematic. I fully admit that I am nowhere near an agriculture specialist, but it doesn’t take one to realize that there is inherent, significant variability in organic – different farms, soils, weather conditions, types and amounts of ‘natural’ pesticides/herbicides used, self-monitoring of heavy metal exposure, large scale vs small scale, irrigation systems, post-harvest processing, storage conditions, etc. From what I’ve gathered from those more knowledgable than I in the agricultural sciences, the ideal food system will go beyond simple terms like organic and conventional, and will likely utilize technologies/methodologies from both sides (note that this would make this ideal food system inherently not ‘organic’ and why I do not support an entirely ‘organic’ food system). If we’re calling for the ideal food system, we should be calling for the best practices, not the most idealistic sentiments.

It’s important to acknowledge that many choose to eat organic foods beyond nutrition-related reasons. I certainly support endeavors to eat for more than just nutrients, but again, it’s important to be critical about whether the solution is as simple as ‘organic’ versus ‘conventional’ – is large scale organic going to fight for workers’ rights and social justice issues much like a small farm that can’t afford a USDA certified organic label? Is your organic food really free of ‘chemicals’? Or is it simply grown using non-synthetic chemicals, with just as fear-mongering toxicity data? Are organic monocultures really much better than conventional? Is an organic factory farm better than a conventional factory farm? Is the health of an animal on a conventional farm receiving medication really better off than one on an organic farm receiving homeopathic or phytotherapeutic medicinal products? One place I think organic gets it right is the antibiotic issue – see here – the FDA is working on the overuse of antibiotics in conventional agriculture – see here. For a further read on agriculture and antibiotic use, see this scienceblogs.com post. Organic vs Conventional is hardly a black and white issue, and illustrating it as one does nothing but create a yelling match between both sides.

My frustration with organic stems from its foundation – this fairytale that everything natural is good and we must grow foods in natural ways. Nothing about agriculture is ‘natural’ – it’s an uniquely human innovation. Humans have always used technology when it comes to food – from the first application of fire, to the tractor, and now to pesticides/herbicides/genetic modification. I understand people’s discomfort with these issues – not everyone is a toxicologist, or a genomicist. It’s one thing to be skeptical of new technologies and ask for more transparency and further testing of technologies – it’s another thing to all out refuse to use these because they are ‘unnatural’. Nothing about organic pesticides/herbicides being from natural sources changes their LD50. Nothing about organic crops changes the fact that they are the end result of 10,000 years of genetic modification via artificial selection. The more advanced technologies get, the more people will fear them – it’s the role of scientists to explain these technologies to the non-scientific consumer.

We certainly live in a time where our way of producing food needs reform – agriculture is a major contributor to greenhouse gases, fisheries are being depleted, we waste an absurd amount of the food we produce, garbage from our food packaging litters the oceans and damages ecosystems/animals, workers’ rights are constantly violated, agricultural systems/economies have become reliant on a few staple crops, chronic diseases are on the rise while many still remain food insecure, and many developing countries continue to grow, developing food systems that may or may not be sustainable. Looking at these very systemic, and global issues, the fixation on organic versus conventional just seems narrow minded and myopic. In addressing these problems, we cannot afford to deny the use of any technology based on whether they fall under an organic title or not. There are 7billion+ people are the earth – that is (arguably) an ‘unnatural’ amount, and will take ‘unnatural’ solutions.

For more readings on this topic, I suggest exploring the following:

http://rodaleinstitute.org/organic-p…leen-merrigan/
http://www.biofortified.org/
http://www.safefruitsandveggies.com/…nel-report.pdf
http://envirocancer.cornell.edu/fact…foodSafety.pdf
http://npic.orst.edu/health/residue.html
http://blogs.scientificamerican.com/…l-agriculture/
http://www.hendpg.org/
http://www.fao.org/fileadmin/user_up…t_Jan_2012.pdf
http://www.fao.org/docrep/u8480e/u8480e0l.htm
http://www.newyorker.com/online/blog…fied-food.html
http://www.businessweek.com/articles…feed-the-world
http://www.ams.usda.gov/AMSv1.0/ams….ome&acct=AMSPW
http://www.cdc.gov/narms/resources/threats.html

Posted 13th July by Kevin Klatt

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