Eat Your Fruits and Veggies -Ignore ‘Dirty Dozen’?

USA Today 3/17/21: These 12 fruits and vegetables contain more pesticide residue than others, ‘Dirty Dozen’ study says

An excerpt: “The 2021 “Dirty Dozen,” released Wednesday by the Environmental Working Group, ranked pesticide residue levels of fruits and vegetables based on samples taken by the U.S. Department of Agriculture and the U.S. Food and Drug Administration…’The most important thing is that everyone should be eating lots of fruits and vegetables…We do recommend you try to reduce your pesticide exposure.'”

From Detroit Free Press: Environmental group adds 3 vegetables to its annual Dirty Dozen list

“USDA’s Pesticide Data Program report finds that 99% of samples tested fell below the safety standards set by the Environmental Protection Agency…Only one in 10 Americans eat enough fruits and vegetables daily, according to the Centers for Disease Control and Prevention…Dirty Dozen list creates fear and disparages consumers from buying — organic or not.”

Related article: NY Times, Nicholas Kristof: What are Sperm Telling Us? “Scientists are concerned by falling sperm counts and declining egg quality. Endocrine-disrupting chemicals may be the problem.”

My take: It is concerning that many foods have pesticides. However, adequate fruit and vegetables in the diet offers many health advantages and this is probably a greater priority.

Related blog posts:

Electrons and Organic Food

I still remember the Heisenberg uncertainty principle (Heisenberg states the uncertainty principle – PBS) from high school physics –thanks Mr. Pryor!  What quantum physicists don’t realize is that it is a leap of faith for anyone to believe in electrons much less to be concerned about measuring factors like speed or position.  I’ve never seen an electron but I’ve been convinced that they exist.

With organic foods, many people believe a health benefit exists, but does it and can it be proven?  A recent review weighs in (Ann Intern Med 2012; 157: 348-66) –thanks to Seth Marcus for pointing out this article.

This review from Stanford has been reported in multiple outlets and the soundbite is that organic foods are not better than conventional foods.  For example, the New York Times reports that the researchers “concluded that fruits and vegetables labeled organic were, on average, no more nutritious than their conventional counterparts, which tend to be far less expensive. Nor were they any less likely to be contaminated by dangerous bacteria like E. Coli.” Ultimately, “the researchers also found no obvious health advantages to organic meats.”

This is a vast oversimplification of this review.  So what did the researchers find and what were the limitations?

First –some background:

  • In 2010, U.S. sales of organic foods had increased to $26.7 billion; in contrast, only $3.6 billion was spent in 1997.
  • There are a number of different standards for organic foods, including U.S. Department of Agriculture (USDA), European Economic Community (EEC), and international federation of organic agriculture movement (IFOAM).
  • Typically organic foods are grown without synthetic pesticides or fertilizers or routine use of antibiotics/growth hormone.
  • Consumers often purchase organic foods due to concerns about effects of farming practices on environment, human health, animal welfare or perceptions of better taste.
  • Inclusion criteria for the cited reference allowed for 17 human studies and 223 nutrient/contamination studies of the initial 5908 potential relevant articles.

Key findings:

  • Conventional foods had 30% higher risk for pesticide contamination.
  • Conventional chicken and pork were more likely to have bacteria resistant to 3 or more antibiotics (33% risk difference).
  • Both organic and conventional products had frequent contamination with bacteria like Salmonella and Campylobacter.  Organic produce had higher risk for contamination with E. coli; this may have been due to some organic farms which used manure for fertilization.
  • There was not evidence that the organic foods were more nutritious.
  • Organic foods had higher levels of total phenols and ω-3 fatty acids.

Limitations:

  • No long-term studies of health outcomes have been performed.  The study with the longest duration included in this analysis was 2 years; the shortest was two days.
  • Variation in organic practices. Produce studies may not have reflected real-world organic practices.
  • Overall sample sizes were small (in total 13,806 human participants in 14 unique populations).
  • Reporting/publication bias.
  • Adherence with organic diets was varied; only 5 of the human studies evaluated participants who consumed a predominantly organic diet.

So, when one looks at this review, there are measurable differences in exposure to pesticides and antibiotic-resistant bacteria, despite variation in organic practices.  Specific nutrients are largely the same.  Whether any of these changes have a long-term health benefit is not known and would require an expensive long-term study to sort out.

 

One approach towards organic foods has been recommended by the Environmental Working Group.  They recommend “buying only organic when purchasing foods that contain the highest concentrations of pesticides, otherwise known as ‘the dirty dozen‘: peaches, strawberries, nectarines, apples, spinach, celery, pears, sweet bell peppers, cherries, potatoes, lettuce, and imported grapes” (Am J Clin Nutr 2010; 9 (suppl): 1499S-1505S).  This reference which discusses foods and potential hormonal effects on puberty goes on to state, “the biggest environmental exposure…is the ready availability of energy-dense foods” which contribute to obesity.

Related link:

Why are we seeing so many more cases

What do you know about the “exposome”?