April 2015 Issue
Organic vs Conventional: Which Is Better?
By Marsha McCulloch, MS, RD, LD
Vol. 17 No. 4 P. 40
Today's Dietitian speaks with agricultural, nutrition, and toxicology experts about organically and conventionally grown foods and their impact on human health and the environment.
News headlines either promoting or dismissing the merits of organic foods grab consumer interest but often fail to tell the whole story. A 2012 Stanford University meta-analysis published in Annals of Internal Medicine prompted headlines that organic foods were not more nutritious than conventionally grown foods, while a 2014 meta-analysis in the British Journal of Nutrition generated headlines with the opposite conclusion. If you read the studies, however, you see that both found that organic foods were significantly higher in certain antioxidants and lower in pesticide residues than their conventional counterparts. In fact, a study published online in February in Environmental Health Perspectives, which assessed long-term dietary exposure to 14 organophosphate (OP) pesticides in 4,466 adults from the Multi-Ethnic Study of Atherosclerosis, estimated that individuals who eat organic foods have about one-half the dietary pesticide exposure of those who eat conventional foods; however, all exposures were well within the Environmental Protection Agency's (EPA) established safe limits.
What also fails to make the headlines are the countless variables that can impact the nutritional composition of food crops, such as variations from field to field and growing season to growing season, or the fact that some of the researchers publishing such studies may have little understanding of agriculture. More importantly, in their focus on nutrients, the popular press may gloss over the environmental benefits of organic agriculture. Gaining a well-informed perspective on both organically and conventionally produced foods requires drawing upon those with in-depth knowledge not only in nutrition, but also in agriculture and environmental health. To help synthesize this expertise, Today's Dietitian (TD) asked the following professionals to participate in our Q&A roundtable discussion:
• Charles Benbrook, PhD, is a research scientist and program leader for Measure to Manage: Farm and Food Diagnostics for Sustainability and Health at the Center for Sustaining Agriculture and Natural Resources at Washington State University in Enterprise, Oregon.
• Ashley Colpaart, MS, RDN, is a doctoral candidate in food systems at Colorado State University and coeditor of the recently released "Organic Talking Points for Registered Dietitian Nutritionists (RDNs)" published by the Hunger and Environmental Nutrition (HEN) Dietetic Practice Group of the Academy of Nutrition and Dietetics.
• Rodney Dietert, PhD, is a professor of immunotoxicology at Cornell University in Ithaca, New York. He has authored, coauthored, and edited more than 300 publications mostly focused on early-life environmental risk factors for the developing immune system and programming of later-life and noncommunicable diseases, such as cancer and asthma.
• Diana Dyer, MS, RD, is the author of A Dietitian's Cancer Story, the proceeds of which are donated to The American Institute for Cancer Research. She started an organic farm in 2009 and developed HEN's School-to-Farm Program for dietetics students and interns.
• Mary Jo Forbord, RDN, is the Morris Healthy Eating Coordinator at the University of Minnesota, Morris, and a past chair of HEN. She and her husband have a USDA organic certified farm.
• Ruth Frechman, MA, RDN, CPT, is the owner of On the Weigh, a nutrition consulting business, and is the author of the multiaward-winning book The Food Is My Friend Diet.
• Jack E. Housenger is the director of the Office of Pesticide Programs at the Office of Chemical Safety and Pollution Prevention at the EPA.
• Karen Klonsky, PhD, is a specialist in cooperative extension in the department of Agricultural and Resource Economics at the University of California at Davis.
• Bruce Lanphear, MD, MPH, is a health sciences professor at Simon Fraser University in Vancouver, British Columbia, Canada, and a senior scientist at the Child & Family Research Institute at BC Children's Hospital.
• Barbara Ruhs, MS, RDN, LDN, is the owner of Neighborhood Nutrition, a nutrition communications and retail health marketing business, and is a former supermarket dietitian. In 2010, she launched the annual Supermarket Dietitian Symposium in partnership with Oldways Preservation Trust.
• Carl Winter, PhD, is an extension food toxicologist and vice chair of the department of food science and technology at the University of California at Davis. He has expertise in pesticide residues, risk assessment, and risk communication.
TD: How would you summarize the nutritional differences between conventionally grown and organically grown foods?
Frechman: In a word—confusion! For every study that says organic food is nutritionally superior, there's another study that says the differences are negligible. One factor that complicates the comparison is the differences in soil used to grow food.
Colpaart: Scientific conclusions of significant nutrient advantage across all sectors of organic foods are unsettled, but evidence does suggest that organic meat, poultry, and dairy products naturally are higher in omega-3 fatty acids than comparable conventional products. This likely is related to fresh forage in the diet of the organically raised animals.
Dyer: The most recent meta-analysis in the British Journal of Nutrition shows significantly increased antioxidant content in organically grown produce. This study also showed that, overall, organically raised produce had reduced pesticide levels and decreased levels of the toxic heavy metal cadmium. Focusing only on nutrient differences distracts from issues of deeper concern, including the impact of farming methods on both public and environmental health. Several studies of both adults and children have shown that eating only organic foods for a relatively short period of time significantly reduces levels of potentially harmful pesticides in the body.
TD: Are there significant health risks linked to the pesticides or technologies used in conventional food production?
Dyer: We know so little about this diverse ecosystem to which we belong. Conventional agriculture consists of practices, including the use of genetically modified (GM) seeds, which are intentionally depleting our planet's vast biodiversity, which includes the extensive microbial life in our soil that's only beginning to be understood for its role in overall health.
Dietert: Humans are not what we thought less than a decade ago. Our microbiota outnumbers our mammalian cells by a 10-to-1 ratio, and our microbiome is the gatekeeper for our interaction with the environment. Safety tests of pesticides typically don't consider microbial toxicity. Limited diversity of the gut microbiome, particularly in young children, sets us up for later-life immune dysfunction and misregulated inflammation, which underlie noncommunicable (chronic) diseases, such as heart disease, cancer, obesity, and autoimmune conditions.
Forbord: Yes, there are significant risks, especially for farm families and children. Members of my family have been hospitalized for acute pesticide toxicity. That's why we transitioned out of conventional production more than a decade ago. It doesn't make sense to spray foods with poison when we can grow nutritious, healthful foods without them.
Winter: From a consumer standpoint, the typical levels of pesticides consumed are so low as to not pose any health risk. Our typical exposures to pesticides from food often are at levels that are at least 10,000 times lower than levels given to laboratory animals every day throughout their lifetimes, which don't show any toxicological effects. I'm also unaware of any credible scientific data demonstrating that foods produced using genetic engineering are riskier than their non-GM counterparts.
TD: Are the health risks of pesticides outweighed by the benefits of eating conventionally grown produce?
Ruhs: The food grown in the United States is among the safest food in the world. There's much more harm in saying there are pesticides or other dangerous chemicals on our fruits and vegetables than there is in encouraging people to eat more fruits and vegetables. Pesticide use today isn't what it was in previous decades. It's very specific so that farmers can target the exact bugs that are attacking their crops rather than wasting money on unnecessary pesticides. There also are very specific regulations on what pesticides can be applied and how much residue can be on the crop when it's sold.
Frechman: If people are afraid to consume fruits and vegetables because of pesticides, they're missing out on nutrients important to their health. A 2012 peer-reviewed analysis in Food and Chemical Toxicology stated that approximately 20,000 cancer cases could be prevented every year if half of Americans ate one more serving of fruits and vegetables per day. The study was based on conventional produce.
TD: There's been debate about the healthfulness of organic pesticides. Are organic pesticides more healthful than conventional pesticides?
Benbrook: Those advancing this message always point to botanical, natural insecticides that were never used widely by organic farmers and aren't used anymore in the United States. There are a few natural pesticides approved for use in organic farming, but they are all far less toxic than the conventional pesticides they displace.
Winter: Neither conventional nor organic pesticides pose any real health risk to consumers so the differentiation between these pesticides is moot. Organic pesticides typically are naturally occurring, while most conventional pesticides are synthetic, but they all obey the principles of toxicology.
Forbord: As a certified organic farmer, I rely on the abundance of beneficial insects to control unwanted pests, along with the resilience of plants grown in healthful soil teeming with microorganisms—not on pesticides, even if they're approved for organic production.
TD: What are the challenges of measuring differences in actual health outcomes of eating organically vs conventionally grown foods?
Benbrook: Positive health outcomes from a predominantly organic diet generally can't be detected in short-term studies. It's extremely difficult to find a population cohort that consumes only organic food. Plus, essentially all of the likely, positive health outcomes from consumption of a healthful diet depend on several other lifestyle and genetic factors. Selecting organic food tips health trajectories in a positive direction, especially if consumed consistently over several years.
Colpaart: Research has only begun to understand the effects of bioaccumulation, the increase in concentration of a pollutant from the environment to the first organism in a food chain, and biomagnification, an increase in concentration of a pollutant from one link in a food chain to another. Together they mean that even small concentrations of chemicals in the environment can find their way into organisms in high enough dosages to cause problems.
Forbord: Impacts may occur in reproductive harms, in utero, or across generations (by compromising DNA). We're masters in using toxins on our food, yet infants in understanding the effects. It's prudent to proceed with caution.
TD: How might age or genetic differences impact the human body's response to pesticide contamination or technologies used in conventionally grown foods?
Lanphear: Pound for pound, children eat and drink more, so if food or water is contaminated, children get a higher dose for their body weight. There have been fairly consistent study results linking OP pesticides (commonly used on fruit and vegetable crops to kill insects) with either reduction in birth weight or diminished intellectual ability in children, which tend to go hand in hand. Even if the effects are subtle at low levels, such as the loss of a few IQ points, subtle effects across millions of people can cause substantial damage or disease.
Benbrook: Consider PON1 [Paraoxonase 1] genetic polymorphisms or mutations found in an estimated 15% of the US population. Individuals with this genetic anomaly can't metabolize or detoxify OP insecticides as efficiently as the rest of the population. As a result, individuals with PON1 polymorphisms are at heightened risk to the many adverse health consequences following OP insecticide exposures.
TD: Many consumers are familiar with the Environmental Working Group's (EWG) Dirty Dozen shopping guide for produce. What's your opinion about the Dirty Dozen and its impact?
Forbord: It's a good start and consumers are responding favorably. I'm encouraged that dietitians are advising consumers and clients to know and care about how their food is grown and processed.
Klonsky: Avoiding eating the Dirty Dozen may give people a false sense of confidence. Pesticide exposure isn't just from eating nonorganic foods that may have residues. Pesticides can contaminate the air and water.
Housenger: The EPA has reviewed the EWG's Dirty Dozen list on pesticide residues in food and has concluded that the rate of violations of pesticide maximum legal residue limits is very small. That confirms government data showing that food in the marketplace rarely violates the EPA's limits for pesticide residues and confirms our analysis that the food supply is safe.
Ruhs: I think it has confused consumers. People could be missing out on the benefits of fruits and vegetables because they're avoiding produce on the Dirty Dozen list due to pesticide residues that may be easily removed by peeling or washing. If you visited the agricultural operations of those producing foods on the Dirty Dozen list, you'd see that concerns are blown out of proportion.
TD: What are the effects of organic farming practices vs conventional farming practices on crop yields and the environment?
Benbrook: Over time, and assuming skilled management, organic farming builds soil health and increases the volume of nutrients cycling in the soil. Conventional farming produces marginally higher crop yields per acre, but usually a less diverse crop-livestock mix.
Forbord: In conventional farming, biodiversity suffers and soil microbiology declines. Aerial spraying, overspray, and drift threaten food crops not modified to withstand the pesticides. Soil is bare and exposed seven months of the year, resulting in tremendous soil erosion. It isn't our soil to lose. Future generations will pay the price.
Lanphear: People need to become more skeptical of the messages they've been fed, often by the same industry that benefits from them. There are systematic reviews that suggest that for much of the produce, we can achieve yields at comparable—and some argue even better—rates in developing countries without the use of pesticides. If our primary concern were about feeding the world, we could do it, even without pesticides.
TD: If organic farming were the norm, would organic food cost the consumer less?
Klonsky: There's much complexity in determining the price of organically grown food, including various marketing strategies that retailers use. Additionally, there are inherent limits on how much food can be grown organically, based on required farming practices, so it may require us to shift how much we eat of certain foods or import more of certain organic foods.
Benbrook: I'm convinced that once organic food captures 15% of the market in any category, the organic food chain begins capturing economies of scale in processing, packing, distribution, and retail sales comparable to those in conventional value chains. The price of many conventionally produced foods is low artificially, with significant hidden costs imposed on society as a whole. These costs include soil degradation, water pollution, low levels of animal welfare, and poor treatment of often-undocumented farm workers.
TD: If a consumer wants to eat more organic foods, what strategies can dietitians recommend to make them more affordable?
Klonsky: Buying from a CSA [community supported agriculture] generally is the least expensive way to purchase organic foods. You pay a membership fee to a farm and regularly pick up a box of locally grown, fresh produce. You generally don't select what's in the box, which makes it more cost-effective for the farmers and reduces waste because they provide what they're growing at that time.
Dyer: I'd help clients review their time and total food dollar spending for one week, and help them make goals and a plan to negotiate choices in order to have the money for healthful organic foods and time for food prep. Expensive, highly processed organic foods wouldn't make it into my professional recommendations.
TD: What trends do you foresee in organic food production over the next 15 years?
Dietert: The big question over the next 15 years is which form of agriculture will fully embrace the microbiome as an integral part of human health. Organically grown food provides an opportunity to begin with the plants themselves, where soil and plant-based microbes can be used to facilitate crop production and provide a seamless connection to the consumer's microbiota.
Forbord: Transparency and more transparency. People want to know who produced their food, how, and where. They want to know that the people who grew it aren't harmed in the process and are treated fairly. Buying organic and/or fair-trade food addresses this.
Ruhs: As big supercenters try to increase the profitability of their stores by focusing on the produce department (an area that's typically underperformed), we're seeing them commit to selling organic fruits and vegetables. So, organic food is going to become more affordable for the average person.
— Marsha McCulloch, MS, RD, LD, is a nutrition writer and consultant based in South Dakota.