No, a study has not shown that Organic food is “healthier”

This sunday CBS news aired a program about GMOs. I didn’t watch it (I don’t own a TV) but I’ve read a summary on CBS’s website. The CBS news story accurately stated that there’s no evidence that Organic food is healthier than typical food or that GMO food is any less healthy.

In response many anti-GMO proponents have been sharing an article via the LA times that indicate Organic food is in fact healthier than standard and GMO food. Today I’m going to pick apart this article piece by piece and show how it’s an example of bad Science Journalism at best and an attempt by the paper to find some positive arguments in favor of Organic foods where there is none at worst.

I’m not even sure why this has shown up in my news stream lately (considering that it’s a year old), but many people are circulating an article by Monte Morin of the LA Times entitled: Organic foods are more nutritious, according to review of 343 studies. The article purportadely shows that Organic food is healthier than traditional (GMO) food. The basic premise is that organic foods are shown to actually be healthier because they contain higher levels of antioxidants and lower levels of cadmium and pesticides. Both of these conclusions are false.

As an aside the LA Times article doesn’t even link to the original scholarly article, which is simply bad form. Here is the actual article.

From the LA Times article (emphasis mine):

After reviewing 343 studies on the topic, researchers in Europe and the United States concluded that organic crops and organic-crop-based foods contained higher concentrations of antioxidants on average than conventionally grown foods.

At the same time, the researchers found that conventional foods contained greater concentrations of residual pesticides and the toxic metal cadmium.

On the basis this would seem to be evidence that Organic food is in fact “healthier”. But the problem is: healthier is a bit of a mis-nomer. Some foods are certainly “unhealthy” in that they provide minimal nutritional value and in large quantities can do harm to the body. A twinkie is a good example: other than providing an energy boost in the form of a high dosage of carbohydrates and biolipids it provides no nutritional value. But the claim that certain foods are “healthier” than others is facile at best. Certain foods contain higher levels of nutrients than others, and many nutrients are not present in different foods. This is the reason why nutritionists recommend a variety of different types of foods.

Now that I’ve dispensed with the problematic term “healthier”, lets de-compact the claims made by the article.

The antioxidant nonsense is in fact covered in a later paragraph (emphasis mine):

It’s not entirely clear to scientists whether the human body can absorb the extra antioxidants in organic foods and put them to use.

Although Benbrook and his colleagues said they suspected the antioxidants could be used by the body to combat damaging free radicals, they could not say so conclusively.

By “not entirely clear’ Morin should have written “there’s no evidence to suggest”. First, there isn’t any good evidence that antioxidants have any effect on cancer survivability or a reduced susceptibility to contracting cancer¹⁾Cortés-Jofré, M., Rueda, J.-R., Corsini-Muñoz, G., Fonseca-Cortés, C., Caraballoso, M., & Bonfill Cosp, X. (2012). Drugs for preventing lung cancer in healthy people. The Cochrane Database of Systematic Reviews, 10, CD002141. http://doi.org/10.1002/14651858.CD002141.pub2²⁾Jiang, L., Yang, K., Tian, J., Guan, Q., Yao, N., Cao, N., … Yang, S. (2010). Efficacy of antioxidant vitamins and selenium supplement in prostate cancer prevention: a meta-analysis of randomized controlled trials. Nutrition and Cancer, 62(6), 719–727. http://doi.org/10.1080/01635581.2010.494335³⁾Bjelakovic, G., Nikolova, D., & Gluud, C. (2013). Meta-Regression Analyses, Meta-Analyses, and Trial Sequential Analyses of the Effects of Supplementation with Beta-Carotene, Vitamin A, and Vitamin E Singly or in Different Combinations on All-Cause Mortality: Do We Have Evidence for Lack of Harm? PLoS ONE, 8(9). http://doi.org/10.1371/journal.pone.0074558⁴⁾Abner, E. L., Schmitt, F. A., Mendiondo, M. S., Marcum, J. L., & Kryscio, R. J. (2011). Vitamin E and all-cause mortality: A meta-analysis. Current Aging Science, 4(2), 158–170. or reduces risk of cardiovascular disease. ⁵⁾Rees, K., Hartley, L., Day, C., Flowers, N., Clarke, A., & Stranges, S. (2013). Selenium supplementation for the primary prevention of cardiovascular disease. The Cochrane Database of Systematic Reviews, 1, CD009671. http://doi.org/10.1002/14651858.CD009671.pub2⁶⁾Shekelle, P. G., Morton, S. C., Jungvig, L. K., Udani, J., Spar, M., Tu, W., … Hardy, M. (2004). Effect of Supplemental Vitamin E for the Prevention and Treatment of Cardiovascular Disease. Journal of General Internal Medicine, 19(4), 380–389. http://doi.org/10.1111/j.1525-1497.2004.30090.x

So even if the organic foods contained higher levels of antioxidants, the antioxidants don’t increase the food’s health benefits in any significant way. Furthermore, in the original journal article, the researchers were unable to identify any sort of mechanism which would explain why the Organic produce contained more antioxidants.

Another claim made later in the article has to do with pesticide use (emphasis mine):

When comparing organic and conventional crops, Benbrook and his colleagues found that conventionally grown fruits and vegetables were four times more likely to contain pesticide residues. That finding was based on 11 of the examined studies and did not evaluate the quantity of pesticides, Benbrook said.

Looking at 11 articles in a meta-analysis of 343 for a result is just simply not statistically appropriate. In addition, the study only looked at the presence of residue, not the amount of residue. Lastly, the pesticide residues can very easily be washed off with soap and water which is just good practice for anyone doing food preparation.

The last claim that the article makes also betrays a lack of scientific literacy on the part of Morin:

The findings about antioxidants and pesticide residues were not as surprising as the finding that organic foods were 48% less likely to contain cadmium.

Study authors said it remained unclear why, and what the specific health consequences could be. More research was necessary, they wrote.

Cadmium, which also is present in cigarette smoke, can cause damage to the liver and kidneys at certain levels.

For that reason, the study authors said, people should try to minimize their cadmium intake. However, they wrote, “the exact health benefits associated with reducing cadmium intake levels via a switch to organic food consumption are difficult to estimate.”

Well, cadmium is present in soil and the levels of cadmium is entirely dependant on the soil in which the crop is raised. It has little, if anything, to do with pesticide use as the EPA has not allowed pesticides containing cadmium as an active ingredient to be used since 1990. A review of this article by Professor Tom Sanders, Head of Diabetes and Nutritional Sciences Division, School of Medicine, King’s College London reads as follows (emphasis mine):

Cadmium levels are dependent on the soil in which the plant is grown and have nothing to do with organic certification. There are naturally occurring areas (1,2) in the UK where cadmium levels of are high (e.g. Shipham in Somerset) and home-grown/organic food grown in these areas would therefore be high in cadmium. Cadmium can be high in soils derived from spoil from former lead, zinc and tin mines. Generally, shellfish are regarded as far more important source of cadmium in the diet, especially if fished from areas where sediment is naturally high in Cadmium (ie. South Coast) or from smelting.

In short, this meta-analysis searched for any possible indication that Organic food might be healthier than standard food and found three results: a higher level of antioxidants that have no effect on human health (and the scientists were unable to find a reason why antioxidant levels would be higher in Organic produce), higher levels of pesticide residue in 11 out of 343 studies (the levels were still not nearly enough to cause any detriment to human health), and higher levels of cadmium in traditional crops, a finding that has nothing to do with Organic growing methods.

In short, the study was an attempt to find any positive benefits of Organic food. The LA Times article produced a misleading headline and buried the actual data as far deep into the article as possible. It’s another episode of bad science journalism.

Media Credit

The featured image is Ecologically grown vegetables by Elina Mark. It is available from Wikimedia Commons under a Creative Commons Attribution-Share Alike 3.0 Unported license.