STANFORD, Calif. — You’re in the supermarket eyeing a basket of sweet, juicy plums. You reach for the conventionally grown stone fruit, then decide to spring the extra $1/pound for its organic cousin. You figure you’ve just made the healthier decision by choosing the organic product — but new findings from Stanford University cast some doubt on your thinking.
“There isn’t much difference between organic and conventional foods, if you’re an adult and making a decision based solely on your health,” said Dena Bravata, MD, MS, the senior author of a paper comparing the nutrition of organic and non-organic foods, to be published in the Sept. 4 issue of Annals of Internal Medicine.
A team led by Bravata, a senior affiliate with Stanford’s Center for Health Policy, and Crystal Smith-Spangler, MD, MS, an instructor in the school’s Division of General Medical Disciplines and a physician-investigator at VA Palo Alto Health Care System, did the most comprehensive meta-analysis to date of existing studies comparing organic and conventional foods. They did not find strong evidence that organic foods are more nutritious or carry fewer health risks than conventional alternatives, though consumption of organic foods can reduce the risk of pesticide exposure.
The popularity of organic products, which are generally grown without synthetic pesticides or fertilizers or routine use of antibiotics or growth hormones, is skyrocketing in the United States. Between 1997 and 2011, U.S. sales of organic foods increased from $3.6 billion to $24.4 billion, and many consumers are willing to pay a premium for these products. Organic foods are often twice as expensive as their conventionally grown counterparts.
Although there is a common perception — perhaps based on price alone — that organic foods are better for you than non-organic ones, it remains an open question as to the health benefits. In fact, the Stanford study stemmed from Bravata’s patients asking her again and again about the benefits of organic products. She didn’t know how to advise them.
So Bravata, who is also chief medical officer at the health-care transparency company Castlight Health, did a literature search, uncovering what she called a “confusing body of studies, including some that were not very rigorous, appearing in trade publications.” There wasn’t a comprehensive synthesis of the evidence that included both benefits and harms, she said.
“This was a ripe area in which to do a systematic review,” said first author Smith-Spangler, who jumped on board to conduct the meta-analysis with Bravata and other Stanford colleagues.
For their study, the researchers sifted through thousands of papers and identified 237 of the most relevant to analyze. Those included 17 studies (six of which were randomized clinical trials) of populations consuming organic and conventional diets, and 223 studies that compared either the nutrient levels or the bacterial, fungal or pesticide contamination of various products (fruits, vegetables, grains, meats, milk, poultry, and eggs) grown organically and conventionally. There were no long-term studies of health outcomes of people consuming organic versus conventionally produced food; the duration of the studies involving human subjects ranged from two days to two years.
After analyzing the data, the researchers found little significant difference in health benefits between organic and conventional foods. No consistent differences were seen in the vitamin content of organic products, and only one nutrient — phosphorus — was significantly higher in organic versus conventionally grown produce (and the researchers note that because few people have phosphorous deficiency, this has little clinical significance). There was also no difference in protein or fat content between organic and conventional milk, though evidence from a limited number of studies suggested that organic milk may contain significantly higher levels of omega-3 fatty acids.
The researchers were also unable to identify specific fruits and vegetables for which organic appeared the consistently healthier choice, despite running what Bravata called “tons of analyses.”
“Some believe that organic food is always healthier and more nutritious,” said Smith-Spangler, who is also an instructor of medicine at the School of Medicine. “We were a little surprised that we didn’t find that.”
The review yielded scant evidence that conventional foods posed greater health risks than organic products. While researchers found that organic produce is 30 percent less likely to be contaminated with pesticides than conventional fruits and vegetables, organic foods are not necessarily 100 percent free of pesticides. What’s more, as the researchers noted, the pesticide levels of all foods fell within the allowable safety limits. Two studies of children consuming organic and conventional diets did find lower levels of pesticide residues in the urine of children on organic diets, though the levels of urinary pesticides in both groups of children were below the allowable safety thresholds. Also, organic chicken and pork appeared to reduce exposure to antibiotic-resistant bacteria, but the clinical significance of this is unclear.
As for what the findings mean for consumers, the researchers said their aim is to educate people, not to discourage them from making organic purchases. “If you look beyond health effects, there are plenty of other reasons to buy organic instead of conventional,” noted Bravata. She listed taste preferences and concerns about the effects of conventional farming practices on the environment and animal welfare as some of the reasons people choose organic products.
“Our goal was to shed light on what the evidence is,” said Smith-Spangler. “This is information that people can use to make their own decisions based on their level of concern about pesticides, their budget and other considerations.”
She also said that people should aim for healthier diets overall. She emphasized the importance of eating of fruits and vegetables, “however they are grown,” noting that most Americans don’t consume the recommended amount.
In discussing limitations of their work, the researchers noted the heterogeneity of the studies they reviewed due to differences in testing methods; physical factors affecting the food, such as weather and soil type; and great variation among organic farming methods. With regard to the latter, there may be specific organic practices (for example, the way that manure fertilizer, a risk for bacterial contamination, is used and handled) that could yield a safer product of higher nutritional quality.
“What I learned is there’s a lot of variation between farming practices,” said Smith-Spangler. “It appears there are a lot of different factors that are important in predicting nutritional quality and harms.”
Other Stanford co-authors are Margaret Brandeau, PhD, the Coleman F. Fung Professor in the School of Engineering; medical students Grace Hunter, J. Clay Bavinger and Maren Pearson; research assistant Paul Eschbach; Vandana Sundaram, MPH, assistant director for research at CHP/PCOR; Hau Liu, MD, MBA, clinical assistant professor of medicine at Stanford and senior director at Castlight Health; Patricia Schirmer, MD, infectious disease physician with the Veterans Affairs Palo Alto Health Care System; medical librarian Christopher Stave, MLS; and Ingram Olkin, PhD, professor emeritus of statistics and of education. The authors received no external funding for this study.
Information about Stanford’s Department of Medicine, which supported the work, is available at http://medicine.stanford.edu. The Center for Health Policy is a unit of the Freeman Spogli Institute for International Studies at Stanford.
The Stanford University School of Medicine consistently ranks among the nation’s top medical schools, integrating research, medical education, patient care and community service. For more news about the school, please visit http://mednews.stanford.edu. The medical school is part of Stanford Medicine, which includes Stanford Hospital & Clinics and Lucile Packard Children’s Hospital. For information about all three, please visit http://stanfordmedicine.org/about/news.html.
BROADCAST MEDIA CONTACT: M.A. Malone at (650) 723-6912 (firstname.lastname@example.org)
—————- The Following are Concerns of experimenter bias, from the Engineering Evil site.
* First off Oganics that are 30% less likely to be contaminated by Pesticides than Conventional are Not Organic: Any significant Pesticide Crop should of been omitted from the Organic side of the Meta Analysis
* The effect of Food Pesticide Exposure Effects can be found all over this site
Removed All other COI Info? (UPDATED AS 5 SEP 12)
* The paid research by Monsanto. The Venture Capital offered to secure Patents on Research through the Gates Foundation and others, The Job Placement services Bio Tech Companies etc…..
Makes little difference if ” The authors received no external funding for this study ” since the one who employs the researchers does….
IT APPEARS STANFORD changed their search engines just recently…….You have to do an Advanced Search…Type in Monsanto, or Gates..They do not come up on a regular search…If that does not work, I have copies of the PDF and Screen Shots…I can take the time to post.. 😉
Removed all other COI Information: Just Follow the Link, and Connect the dots…I honestly don’t know how Stanford or Many Universities could avoid any COI’s, even if it wanted to now.
Go to Page 6 of this PDF…
It appears that the Gates Foundation May in Cooperation with other firms,Supplies Start up Capital to Stanford Researchers (As well as Others) in Hopes of Aquiring Patents….It is no seceret, the Gates Foundation is a major source of research dollars to many institutions. Whether the Gates foundation is doing it for charity, or other motivations is up to the reader.
* In any Case Stanford does work with Monsanto a Great Deal.. Go to http://medicine.stanford.edu type in Monsanto on the search… Draw your own Conclusions
Gates Foundation Grants to Stanford
Gates investments in Monsanto, and cooperation with Cargill
The Conflict is not directly by the Researchers, but the Institution
Recent Gates Foundation Grant List to Stanford: Source Gates Foundation
2012 Stanford University College-Ready Education (U.S.) United States $274,999 2012 Stanford University College-Ready Education (U.S.) United States $30,000 2012 Stanford University College-Ready Education (U.S.) United States $30,000 2011 Stanford University Charitable Sector Support Global Policy and Advocacy $150,000 2011 Stanford University Discovery Global Health $100,000 2011 Stanford University Water, Sanitation, & Hygiene Global Development $397,100 2011 Stanford University Water, Sanitation, & Hygiene Global Development $100,000 2011 Stanford University Discovery Global Health $100,000 2011 American Education Finance Association Advocacy & Public Policy United States $84,870 2010 Stanford University Discovery Global Health $100,000 2010 Stanford University Advocacy & Public Policy Global Policy and Advocacy $50,000 2010 Stanford University – John W. Gardner Center for Youth and Their Communities College-Ready Education (U.S.) United States $1,541,091 2010 Stanford University Agricultural Development Global Development $995,844 2010 Stanford University Postsecondary Education United States $1,433,143 2010 Stanford University Vaccines Global Health $1,000,000 2010 Carnegie Foundation for the Advancement of Teaching Postsecondary Education United States $4,409,433 2010 Stanford University Discovery Global Health $100,000 2010 Stanford University Discovery Global Health $100,000 2009 Stanford University Postsecondary Education United States $1,400,088 2009 Stanford University Postsecondary Education United States $3,000,000