From: Consumer Reports.org
Sep 5, 2012 10:30 AM
A new review of previous research on organic food is getting a lot of media attention for concluding that the published literature "lacks strong evidence" that organic food is significantly more nutritious than conventionally grown food. But news reports covering the findings may be oversimplifying or distorting what the study really found, according to our in-house experts, and consumers shouldn't be misled into believing that there isn't a benefit to paying more for organics, particularly for certain populations.
The review, conducted by researchers at Stanford University, was a meta-analysis of data from 240 studies comparing organically grown versus conventionally grown food. Seventeen of the studies were done in humans; the rest looked just at the foods themselves. The researchers looked at three main variables: health outcomes, nutrient levels, and levels of contaminants, including pesticide residues. They concluded that "the published literature lacks strong evidence that organic foods are significantly more nutritious than conventional foods," though consuming them "may reduce exposure to pesticide residues and antibiotic-resistant bacteria."
But the study has serious limitations, several of which the authors acknowledge. Among them:
- The analysis included plenty of studies that did find a nutritional benefit to eating organic food, such as higher levels of phosphorous and phenols (a type of antioxidant compound) in organic produce and more omega-3 fatty acids in organic milk and chicken. Some other studies weren't able to identify a benefit, meaning the findings overall were heterogeneous, or mixed—which is very different from "no benefit" across the board.
- Only three of the 17 human studies in the analysis looked at health outcomes, and two of those focused on allergies in children—an odd metric for comparing organic to conventional diets, since there's no reason that organic diets should correlate with fewer allergies. "That isn't part of what organic food production even is and it isn't surprising to learn there may not be any difference" in the rates of allergies between children who eat organically and those who don't, says Urvashi Rangan, Ph.D., director of consumer safety and sustainability for Consumer Reports, adding that it was interesting that the authors also found one study that did suggest a benefit, for childhood eczema.
- It could take many years for the cumulative effects of pesticide buildup in the body from eating conventionally grown food to show up. Cancer risks, for example, are calculated over long periods of exposure to carcinogens. The human studies in the Stanford analysis lasted at most two years.
- The study downplays the importance of the prohibition of antibiotics in organic agriculture, which can help counter the serious public-health problem of antibiotic-resistant bacteria. Such bacteria have increased greatly in prevalence in recent years, possibly due to the routine use of antibiotics in conventionally raised farm animals. Indeed, the meta-analysis determined that conventionally produced chicken and pork had a 33 percent higher risk for bacteria that's known to be resistant to at least three antibiotics.
- The perception of better nutrition is only one reason that people might choose to eat organically. Even if the research in that area remains murky, it's clear that organic diets provide less exposure to pesticides and antibiotics, two potential safety benefits, and that organic agriculture is better for the environment. A nationally representative poll of Americans conducted by Consumer Reports earlier this year found that 86 percent want their local supermarkets to carry meat raised without antibiotics, and the majority said they'd be willing to pay extra for that feature.
"Organic was meant as a healthier way of farming that is good for the environment—and that has been proven true," Rangan says. "Fewer pesticides and antibiotics, 100% organic animal feed (which cannot have poultry litter and other animal byproducts), hygiene management on the farm: These are all healthier practices for the environment and in some cases, humans too. In fact, we are learning more and more about the benefits that organic farming and sustainable agricultural practices can have on the health of people."
Bottom line: We stand by our long-held advice. It's worth it to buy organic versions of the foods that are likely to have the highest levels of pesticides when grown conventionally, as well as organic poultry and milk, to reduce exposure to antibiotics. Those choices are especially important for pregnant women and children.
Watch a video about when it pays to buy organic. Learn which items you should buy organic for babies and kids, and which you can skip.
Are Organic Foods Safer or Healthier Than Conventional Alternatives? [Annals of Internal Medicine]