Kristin Jones, one of our readers, commented asking what we thought of the study done by the London School of Hygiene & Tropical Medicine that organic vegetables are no healthier than those grown conventionally.
Studies of food "health" focus on the numbers of micronutrients (vitamins and minerals) found in plants. Different growing conditions can have an effect on these concentrations. Maintaining high soil quality is essential to this. Other factors include preventing overcrowding from weeds and other crops (thinning), adequate sunshine and water, pest management, and fertilizing.
Fertilizing can be done with organic (in the scientific sense) materials such as manure, compost, fish, and other ammendments, or with synthetic nitrogen and phosphorus. The second approach is indicative of a focus more on the macronutrient quality of the vegetable, or total yield (the amount of starches, sugars, protien, and fats produced). It lacks the diversity and complexity of other smaller, diverse nutrients present in materials like manure and compost that are essential to developing a rich soil and consequently nutrient-rich plants. However, other factors such as not tilling and nurturing colonies of beneficial fungi and microbial life is also essential for soil health.
In this way, I would generally consider organic practices to be superior to conventional ones for producing quality vegetables -- the system is more complex. However, the biggest factors affecting vegetable micronutrient density can be managed poorly or well in either a certified organic or conventional system. Many certified farms use extensive tilling as a way to control weeds in the absence of chemical herbicides. This can lead to compaction of the soil and disruption of structure and microbes that can be formed and maintained in a no-till system. Organic methods are not the be-all and end-all of good farm and soil management, and one can as easily produce a sad-looking apple from an organic orchard as a conventional one, depending on the differences in management style.
However, this study does acknowledge that there are, generally, differences between organic and conventional produce -- just not ones considered significant enough to affect the general nutritional value of the produce. The Times Online quotes Dr. Dangour, who headed the study:
There is more phosphorus in organic food. Phosphorus is an important mineral but it is available in everything we eat and is not important for public health. Acidity is also higher in organic produce but acidity is about taste and sensory perception and makes no difference at all for health.
A small number of differences in nutrient content were found to exist between organically and conventionally produced crops and livestock but these are unlikely to be of any public health relevance.
Our review indicates that there is currently no evidence to support the selection of organically over conventionally-produced foods on the basis of nutritional superiority.
They clarify, however, that the study did not (and did not intend to) investigate agricultural residues (pesticides, fungicides, and herbicides) on produce, or compare their quality of taste. There have been other inconclusive studies on taste, but my reaction to this study basically boils down to several points:
1) Nutrient content is controlled by two factors: environment (growing methods) and DNA. By nature of just being a vegetable, it's going to contain a certain amount of nutrients. However, soil quality and nutrient availability also affect the resulting micronutrient content of what is grown. Nutrient-dense plants can be grown in either a conventional or organic environment, if the other relevant factors are managed correctly. Nonetheless, it does seem that (small) organic certified farms generally take a healthier approach to farm management than conventional ones, if only for the fact that the certification puts them in the realm of thinking about things like soil quality and general sustainability.
2) Buying organic isn't about the nutrient content. While there are some people who live and die by the claim that their organic tomato has more Vit. C than a conventional one, this isn't the reason that most people who buy organic make the choices that they do. It's about being one step closer to knowing what happened to your food -- was it sprayed with synthetic pesticides? Was it genetically modified? The idea behind organic is that you should be able to answer these questions about your food.
3) Organic is a label, not a guarantee. Organic vegetables will not cure your cancer. They will not make your lame dog get up and dance. They will not do the Moon Walk across your counter in colorful veggie-extacy. Please refer to my earlier post if need be. However, endorsing this label does send a message, especially to the conventional industry -- that people are not satisfied with their current relationship with food, and are willing to pay and support farmers to see a change in the way the system operates. The same can be said of the local (and slow) food movements, which bring you directly in contact with the source of your food. You can tell your farmer exactly what you think and want from them.
4) The study isn't questioning the merits of organic methods, nor it is even claiming that there aren't taste or nutritional differences between organically grown vegetables and conventional ones (see above quote). It is simply saying that for the average consumer, you are not loosing out on vital amounts of nutrients by buying conventional produce instead of organic. Perhaps the motivation behind this whole ordeal is to validate that people can improve their diets to contain healthier foods without necessarily spending the extra bucks?*
Peter Melchett, policy director at the Soil Association, admitted that he was disappointed by the conclusions but said that he was confident that consumers would make their own minds up. (emphasis mine)
This pretty much sums it up. Regardless of this publication, you have the mental capacities to make your own decisions about what is and isn't important to you in the food you buy. What will this study do, then? Maybe attempt to end catty remarks from suburban soccer moms who are absolutely horrified that someone without financial means might feed their child a conventionally grown carrot* or not shell out for a morally superior onsie, ohmigod don't you love your children?!?!? However, it seems to me that supporters of the organic movement are already pretty aware that their purchasing choices are about supporting the kind of agriculture they want to, avoiding bioaccumulation of possibly harmful residues, or any number of other factors that go into the decision outside of micronutrient content.
If you're someone who acknowledges that health -- for yourself, the planet, and the agricultural industry -- is not dictated only by what % RDA Calcium your spinach has per serving, this study at least shouldn't prevent you from buying organic.
*Though there are plenty of ways to make organic "affordable" for anyone, that's a topic worthy of its own post.