Organic or conventional? It’s a choice many shoppers are faced with, over and over. The price difference is totally obvious; it’s right there on the product. The quality difference is much harder. Is the organic milk better for your kids or not? Is the conventional lettuce more likely to carry pathogens?
Leaving aside whether organic agriculture is better for the planet and whether organic livestock have better lives, although there’s a strong case for both of those arguments. Leave aside flavor too, because it’s subjective and variable.
Do organics do us more good (in the form of better nutrition), and do they do us less harm (in the form of fewer contaminants and pathogens)?
Because the risks and the benefits vary by product – meat is different from produce – it’s important to look at each category separately. While every category has the potential to harbor pathogens (such as E. coli), there are some product-specific concerns, including pesticide residue in produce and hormones in milk.
Here’s a rundown of the evidence on nutrition and contamination levels for organic and conventional products in five categories – milk, produce, meat, eggs, and fish – to help you decide whether to buy organic or stick with conventional.
Nutrition: Compared with conventinal milk, organic milk has higher levels of omega-3 fats, which protect against heart disease and may decrease the risk of depression, stroke, cancer, and other diseases, but the quantities are too small to be very meaningful. Milk’s omega-3 content is a function of the cow’s diet, and higher levels reflect more grass.
Contamination: Neither organic nor conventional milk contains antibiotics. By law, every truckload of milk, organic and conventional, is tested for veterinary drugs, including antibiotics, by trained dairy workers. Any load that tests positive is pulled out of the food supply. Organic cows aren’t given antibiotics, and conventional ones are given them only for illness, and their milk isn’t used until after a withdrawal period.
The agricultural pesticide DDT was banned years ago, even though the U.S. Department of Agriculture has found that the pesticide levels are very low., but the USDA mentioned that it is persistent and remains in many cropland soils. It is also in the body fat of the people and most farm animals and wildlife.
Pasteurization fails some of the time, allowing milk contaminated with bacteria to get into the food supply, but there are no reports comparing illnesses caused by organic vs. conventional milk.
Hormones: The issues with milk is that many conventionally raised dairy cows, unlike organic ones, are injected with bovine growth hormone to increase their milk production. The problem isn’t the hormone itself but rather a compound called insulin-like growth factor.
Bottom line: Organic milk has higher omega-3 fat levels, but probably not enough to make a difference. Exposure to pesticides, contaminants or hormones is not a significant risk in either organic or conventional milk.
Nutrition: Many studies have compared the vitamins, minerals, macronutrients and other compounds in organic and conventional produce. The one exception was the phosphorous content of organic produce is higher, although the review, done by Stanford University scientist, calls that finding “not clinically significant.” Along with calcium, phosphorus helps build strong bones and teeth.
Contamination: There are two issues for foods that grow in the ground: pesticides and pathogens. There is widespread agreement that organic produce, while not pesticide-free, has lower residue levels and fewer pesticides. There also isn’t agreement about whether that’s meaningful for human consumption.
As for pathogens, the 2012 Stanford review found that E. coli contamination is slightly more likely in organic than conventional produce.
Bottom line: While there may be no significant nutritional difference between organic and conventional produce, organic does have lower levels of pesticide residue. However, there isn’t universal agreement on the risk of those residues pose.
Nutrition: As with milk, the main issue here is omega-3 fats. Some organic meat and poultry have more of them than conventional products do. The reason is diet: Animals that eat more grass have lower fat levels overall and higher omega-3 levels than animals fed more grain.
Although measurements of omega-3 fats in beef vary, the numbers are low and substantially below what can be found in a serving of salmon.
Contaminants: The USDA randomly tests carcasses for residues of pesticides, contaminants and veterinary drugs including antibiotics. In 2011, it screened for 128 chemicals, and 99 percent of the tested carcasses were free of all of them.
The bigger concern is pathogens. Studies of bacterial contamination levels of organic and conventional meat show widely varying results. These findings suggest that organic meat may be slightly more likely to be contaminated, possibly because no antibiotics are used. But conventional meat is more likely to be contaminated with antibiotic-resistant bacteria.
Bottom line: There doesn’t seem to be much difference, health-wise, between organic or conventional meats. Grass-fed beef has a slight edge over grain-fed because of higher omega-3 levels, but the amounts are possibly too small to affect human health.
Nutrition: As with milk and meat, the omega-3 levels of eggs are affected by the hens’ diet and can be increased by pasturing or diet supplementation for either organic or conventional hens. Eggs high in omega-3s are generally labeled.
Contaminants: There’s very little research on contaminants in eggs. The USDA’s 2011 National Residue Program tested 497 egg samples and found no residues of pesticides, contaminants or veterinary drugs, including antibiotics. This isn’t surprising because, according to Pat Curtis, a poultry scientist at Auburn University, laying hens aren’t routinely given antibiotics, and there is a mandated withdrawal period after they do get the drugs (to treat illness) before their eggs can be sold.
Bottom line: There are no significant differences affecting health between organic and conventional eggs.
The USDA has not issued any organic standards for farmed or shellfish, but several overseas organizations have. Canadians standards prohibit antibiotics and hormones, restrict pesticides and set criteria for acceptable feed. There’s not enough research comparing organic and conventional fish to draw any conclusions about their health benefits.
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