d o c t o r a n d m a m a

Linda Shiue

Linda Shiue
San Francisco Bay Area, California, USA
December 31
I am a physician and spend my free time with my husband and kids, reading everything in sight, eating, traveling, and cooking meals inspired by my travels. These days I'm spending more time at my food blog, spiceboxtravels.com. Please visit me there and follow me on Twitter @spiceboxtravels. Disclaimer: Health information presented here is not intended nor recommended as a substitute for medical advice, diagnosis, or treatment. Always seek the advice of your own physician or other qualified health care professional regarding any medical questions or conditions. © 2010-12 Linda Shiue. All Rights Reserved.

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MAY 21, 2010 8:53AM

Could Eating Fresh Fruits and Vegetables Cause ADHD?

Rate: 13 Flag
Vegetables by Linda Shiue 
A common perception is that too much sugar is what makes kids "hyper." But what about eating fruits and vegetables? It may depend on how well you wash them.
A new study published in Pediatrics suggests a link between commonly used pesticides and the development of ADHD, or Attention Deficit Hyperactivity Disorder.  Researchers tracked levels of the breakdown products of organophosphates, a common class of pesticides, in children's urine and found those with high levels were almost twice as likely to develop ADHD as those with undetectable levels.

Of note, the study population was not a specially selected group (such as farmworkers or children with known ADHD) but data from the general US population, culled from the National Health and Nutrition Examination Survey (2000-2004).  This suggests potential harm from exposure to organophosphate pesticides at levels commonly found in our environment.
As quoted in Reuters, a study author commented: 

"There is growing concern that these pesticides may be related to ADHD," said Marc Weisskopf of the Harvard School of Public Health, who worked on the study. "What this paper specifically highlights is that this may be true even at low concentrations."

Organophosphates are known to be neurotoxins, or harmful to the nervous system.  As such, it is biologically plausible that they could cause alterations leading to ADHD.  They were originally developed for chemical warfare, with one example being Sarin. According to Reuters, there are about 40 organophosphate pesticides registered in the US, including malathion.  Residues from these make their way into our food supply in the form of fresh fruits and vegetables.

The study sample included 1,139 children between 8 and 15 years. The authors conducted structured interviews the children's mothers or another caretaker, and found that 119, or about one in ten, met the criteria for ADHD, which is similar to the prevalence in the overall U.S. population.

For the most common breakdown product, called dimethyl triophosphate, the odds of ADHD almost doubled in kids with above-average levels compared to those without detectable levels.  These numbers were adjusted for gender, age, race/ethnicity, poverty/income ratio, and fasting duration.

The study's lead author, Weisskopf,  emphasized that these results are preliminary, and do not necessarily imply causation.  More studies are needed before contemplating a ban on these pesticides. He recommended:

"A good washing of fruits and vegetables before one eats them would definitely help a lot."
That's sound, common-sense advice.  You don't want to "throw out the baby with the bathwater;" the health benefits of eating fresh fruits and vegetables far outweigh any potential risks from bacterial or chemical contamination.  But it pays to choose and prepare wisely.  You should consider organic produce, when possible, and avoid organophosphate pesticides and insecticides at home.   To see a comprehensive list of which fruits and vegetables are most important to choose organic, see the Environmental Working Group's list.  For all fresh produce, wash well before consuming, to reduce levels of both pesticides and bacteria.  
These are some of the FDA's recommendations for safely preparing fresh produce: 
-Begin with clean hands. Wash your hands for 20 seconds with warm water and soap before and after preparation.
-Cut away any damaged or bruised areas on fresh fruits and vegetables. Produce that looks rotten should be discarded.
-All produce should be thoroughly washed under running water just before eating. This includes produce grown conventionally or organically at home, or purchased from a grocery store or farmer's market.  Even if you plan to peel the produce before eating, it is still important to wash it first.
-Washing fruits and vegetables with soap or detergent or using commercial produce washes is not recommended.
-Scrub firm produce, such as melons and cucumbers, with a clean produce brush.
-Drying produce with a clean cloth towel or paper towel may further reduce bacteria that may be present.
 -You do not need to wash precut, bagged, or packaged produce items like lettuce that are labeled pre-washed and ready to eat. 
© 2010 Linda Shiue 
Maryse F. Bouchard, David C. Bellinger, Robert O. Wright and Marc G. Weisskopf.  Attention-Deficit/Hyperactivity Disorder and Urinary Metabolites of Organophosphate Pesticides. Pediatrics, published online May 17, 2010.

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I knew there had to be a better explanation aside from pediatricians overprescribing medication. Thanks for this, Linda.
Very interesting post, Linda._r
I'm not buying this. But it's an interesting hyoptheses.
Thanks, Linda... the file for health warnings is overflowing this week.
Years ago I read about a Japanese woman whose father had taught her to throughly wash all fruit, to scrub them before eating. He had survived WWII and was obsessed with nuclear fall out. I remember how strange that seemed to me, to wash and scrub and peel fruit, but I did wash my fruit and now I understand how he might have been on to something.....R
Amazing story, I have been watching this story since the study came out. Thanks for your coverage. There is so much more to learn here. As for fruits and veggies with permeable skins, how is washing them going to remove pesticides that have penetrated the surface. Why doesn't anyone just do a study on pesticide removal by washing. I would bet residue remains.
Yep, it's the chemicals. Buy organic. :) Great article.
We wash (with water) and dry our fruits and vegetables anyway, but others might need to be reminded. Regardless of this study, it's just a good idea.
Thank you for bringing this to our attention. This is a well written, thoughtful article. Your openminded view has left us with a better feeling for your own intelligent take on what healthful might be. As I am partial to the organic sector, I feel it may help to recall how our soil quality is poor enough to where it is the organic farmers now that are reclaiming it via tried and true, as well as some newfangled, practices. It's what we put into our soil which gets inside a plant, its fruit and root system. Stands to reason, our children, as well.
This was very informative in an easy way...Thank you, kind Doctor.
Kathy- this is but one of many possible factors. Thanks for commenting.
Joan- thanks.
OES- not definitive, but biologically plausible, as at least part of the puzzle
Catherine- it's overwhelming, the amount of warnings!
Sheila- I do think it's common sense.
Steve- washing is the best we can do where pesticides are involved, but I am sure residue is left and certainly could permeate
sweetfeet- thanks!
Bellwether- it does read as common sense, but I think you are probably more careful than the average consumer if you are doing all of the above already, which is great.
PW- thanks for your comment and insight.
Linnnn- thank you! I was hoping to make this readable and useful, not too technical.
Great post, Linda! I've often wondered about pesticides causing harm, especially to kids. It just doesn't make sense that putting chemicals into our bodies wouldn't become harmful in some way. Thanks for sharing this information!
Why has apple juice replace milk as the bev of choice for kids? Even it you reject milk for its fat content, what's apple juice but concentrated sugar? Linda, what's the appeal?

Another question: Why is so much fruit unfit to eat while all vegs available at the supermark are just fine. Lot of time & money wasted on inedible fruit; except for apples, always good. Would people be better advised to load up on vegs? (Some kids, though, resist vegs; I did.)
See this? American Academy of Pediatrics would have doctors assisting families in the ritual of female circumcision/

Lisa- thanks

Leon- so many comments and questions! Thanks! Apple juice- just sugar, you're right. The apple a day is supposed to be the actual fruit. I heard about the female circumcision piece but have not read yet, will take a look.
Thanks for covering this, Linda - hadn't seen the story yet. This does worry me a bit...because as the data seem to be presented, this is a case of correlation not causation. Until there are further data, I don't think there is a proven link. On the other hand, clearly these toxins in our environment HAVE been linked to health problems, as the Endocrine Society has created a concensus statement to that effect.
Thanks for commenting, Aliquot. I think that you're probably right re: correlation, but no harm in being careful while waiting for evidence to mount. I remember your pesticide post from a few months ago, with the endocrine changes.
Crazy. We do wash all fruits and veggies, and try to buy mostly organic. One issue that concerns me is access to healthy organic food and information - for everyone. There's a notion that organic is always more expensive. It is, but it depends on where you're getting your food.

I know there's a lot of urban agriculture stuff going on in certain cities in the U.S.

In Toronto we have some really good food security, and urban ag. initiatives that provide a lot of good, healthy, organic food to lower income communities.

Its important that everyone have this knowledge and access.

Sorry - this comment is a bit of a tangent from the article but I think your article points out just another reason to increase access.

Thanks for breaking it down and posting!
Thanks for this Linda! My sister is a huge advocate for eliminating pesticides from our environment. She lobbies government agencies and Canada seems to be well on its way in eliminating pesticides for "cosmetic" purposes anyway (to get your lawn completely green and weed-free).

Kim, thanks for commenting. That is great news in Canada. And great to see you back!
The study is fundamentally flawed, not its methodology or data analysis but in its definitions.

Assume that the study proved that pesticides _caused_ ADHD. Then that wouldn't be ADHD, that would be organophosphate pesticide poisoning. And if you're treating it with Adderall, you're a fool.

The purpose of the study wasn't to detect a link between ADHD and pesticides, but to do something else:

Hmm interesting. I've greatly reduced my ADHD by eating more raw greens but than again I'm not a child.