Previously, I shared current research about organic versus conventional choices for milk. This week, the focus will be nutritional and contaminant/pesticide levels of organic versus conventional produce.
Selecting organic produce based on nutritional or contaminant/pesticide content has not been supported by research. Analytical analysis consistently is hampered by wide variability and small sample sizes. The conclusion time and again is “difference was not statistically significant.”
Studies I reviewed involved limited participant numbers as well as limited technique/produce options.
The Mayo Clinic and Stanford University recently examined 50 years’ worth of scientific articles about nutrient content of organic and conventional foods. Each concluded that:
Organic- and conventional-produced food is comparable in nutrient content.
Nutrition or contaminant content is not significant whether organic or conventional.
Is it possible that the $10 billion spent on organic fruits and vegetables in 2010 was based on misinformation, misleading information or ethical decisions rather than health impacts?
In 2009, overall organic food sales reached $24.8 billion. This was more than double that of the organic sales in 2003, yet research continues to find no difference nutritionally or by contaminant level.
Has our physical health or our financial health benefited to that level? Has it doubled since 2003? One must ask exactly who is benefiting, and how have companies directed their efforts to this market? What is the specific rational for consumers to participate?
Proper handling and washing has been found to have the greatest overall effect. Wash any produce under cold running water thoroughly while scrubbing lightly with a vegetable brush.
The second-most important effect is consuming a wide variety of produce. Leafy vegetables such as lettuce and spinach, whether organic or conventional, are the No. 1 cause of food-borne illness, causing 22 percent of food-borne illness. With proper handling and washing, however, these still are valuable overall for one’s food intake.
The most important effect on health from produce is to increase consumption of vegetables and fruit to at least 2½ cups daily of a variety of produce regardless of the growing system.
USDA reviewed 174 publications published between 2000 and 2008 that reviewed contaminant content. The bulk of the studies were published during 2006 and involved review of 48 vegetables, 33 meats, 27 fruits, 17 dairy and nine infant foods. Bottom line was that overall differences were not statistically significant and levels of contaminants not substantial.
There are few well-controlled studies comparing nutritional variances. Nutritional content was affected by variables including soil type, climate, harvest time (crop maturity), processing methods and overall conditions that each impacted various nutrients, and results were found to be nonconclusive.
E. Coli contamination is slightly greater in organic produce compared with conventional produce. Research conducted in 2006 noted 2.9-4.8 times more residues on conventional produce. The recommendation overall was consumers eat less imported produce. Pesticide amounts varied depending on time of year and crop. EPA has determined that specific items such as snap beans, watermelon, tomatoes and potatoes are more likely to contain higher levels of pesticides than other produce. The recommendation was that if one is pregnant or feeding small children, consider organic versions of these specific items.
In 2012, Annals of Internal Medicine published an abstract of 17 studies in humans and 223 studies of nutrient and contaminant levels in foods. Again, the overall conclusion was that studies lack strong evidence that organic foods are significantly more nutritious than conventional foods, though consumption of organic foods may reduce exposure to pesticide residue and antibiotic-resistant bacteria.
wendy.rice@colostate.edu or 382-6461. Wendy Rice is family and consumer science agent for the La Plata County Extension Office.
