Thursday, September 06, 2012

Organic Produce a Go or a No?

Stanford researchers threw some shade on organic produce this week.  After scouring 237 studies collected over forty years, they concluded in a study published Tuesday in the Annals of Internal Medicine* that organic fruits and vegetables offered  no more nutritonal benefits than produce with a side of pesticides. No more vitamins and minerals. Nor did organic mean less E. coli or other worrisome bacteria. However, pay attention my gestating friends and family, organic produce did contain significantly lower rates of pesticide residue (7%) than its conventional counterparts (38%).  But as the study authors noted the levels were generally within what the Environmental Protection Agency has considered safe.

Safe?
Considered safe as in within existing safety limits that might or might not necessarily adequately reflect more recent research linking pesticides in pregnancy and early childhood to learning deficits. According to Sonya Lunder, a senior analyst with the Environmental Working Group, parents and parents-to be don't go organic for an extra boost of phosphorus or Vitamin C:  

Rather, the motivation is to reduce exposure to pesticides, especially for pregnant women and their young children. Organic food advocates point to, for example, three studies published last year, by scientists at Columbia University, the University of California, Berkeley, and Mount Sinai Hospital in Manhattan. The studies identified pregnant women exposed to higher amounts of pesticides known as organophosphates and then followed their children for years. In elementary school, those children had, on average, I.Q.’s several points lower than those of their peers. Stanford Scientists Cast Doubt on Advantages of Organic Meat and Produce, New York Times
Lower IQs? Let's review those studies, all three published last year in the journal Environmental Health Perspectives, all in the same issue.  The one done in the agricultural town of Salinas, California found children born to women with the highest levels of organophosphates in their pregnancy urine scored 7 points lower on intelligence tests than those with moms showing the lowest levels. Not surprising, the women had high levels of pesticides in their urine but not freakishly high according to its authors. The two other studies, conducted in New York City, linked lower childhood intelligence to prenatal exposure to pesticides but found smaller "effects" (i.e. 3 IQ points). However, there were no links between learning/intelligence and exposure in childhood (i.e. after birth). Also, exposure to organophosphates has been cut in half over the last decade but still it's enough to cause a pregnant pause or at least make pregnant women pause before picking up those grapes from Chile.

But what about the study out of Stanford? It reviewed 17 "human studies" in its meta-analysis.  So basically it also looked at studies that measured levels of pesticides and such in people: 
Only 3 of the human studies examined clinical outcomes, finding no significant differences between populations by food type for allergic outcomes (eczema, wheeze, atopic sensitization) or symptomatic Campylobacter infection. Two studies reported significantly lower urinary pesticide levels among children consuming organic versus conventional diets, but studies of biomarker and nutrient levels in serum, urine, breast milk, and semen in adults did not identify clinically meaningful differences. All estimates of differences in nutrient and contaminant levels in foods were highly heterogeneous except for the estimate for phosphorus; phosphorus levels were significantly higher than in conventional produce, although this difference is not clinically significant. Are Organic Foods Safer or Healthier Than Conventional Alternatives?:A Systematic Review, abstract, the Annals of Internal Medicine
Okay so no differences in kids who ate organic versus conventional in terms of allergies, eczema and food poisoning (Campylobacter infection).  So some evidence child who eat organic have less pesticide in the pee. Not any significant differences in pee or anything else in adults.  Basically all organic and conventional looked very similar except for phosphorus but hey why even mention this because it wasn't even significant!

By the way, the media never clarified that the phosphorus difference was not even statistically significant even though it's featured in several major and plenty of D-listed media outlets.  Why even mention it in the news? I suspect it's because of the abstract or press release.  It's statistically insignificant but obviously the largest difference, meaning, the other vitamins etc were equivalent. When asked, the authors suggested it was not meaningful anyhow since people tend to get plenty of phosphorus in their diets anyhow.  It's just an example of an unimportant piece of info getting attention in the media.

Now it's true there are other good reasons for eating organic like health of the planet, farmers and farm workers. Some commentators have suggested the current study takes the focus off these more pressing issues. 

Some have downplayed the nutritional findings as well as the high cost of organic produce even though there's good reason to discuss the cost especially in light of the lack of nutritional benefits. 

On the same day the Stanford study was published we also learned almost 18 million American households struggled last year to provide food of any nutritional merit according to a report out this week by the United States Department of Agriculture.  So 14.9% of  households in 2011 were "food insecure" as in having some difficulty providing food due to limited money and resources (via NPR).  It was a hardship for them to buy food. Almost 6% of households reported this difficulty actually impacted their food intake. So a worrisome number of people changed what or how much they ate and not because they were cutting back on refined carbs or switching to organics. They didn't have the luxury.

So it is important to be clear about the costs and dietary benefits just as it's important to be clear about the risks of pesticide exposure. 

*Would it kill the New York Times and other media to link to the actual study versus Stanford University or other news articles?

Are Organic Foods Safer or Healthier Than Conventional Alternatives?: A Systematic Review

Crystal Smith-Spangler, MD, MS; Margaret L. Brandeau, PhD; Grace E. Hunter, BA; J. Clay Bavinger, BA; Maren Pearson, BS; Paul J. Eschbach; Vandana Sundaram, MPH; Hau Liu, MD, MS, MBA, MPH; Patricia Schirmer, MD; Christopher Stave, MLS; Ingram Olkin, PhD; and Dena M. Bravata, MD, MS

Annals of Internal Medecine. 4 September 2012;157(5):348-366

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