Organics: Are they worth the price?

Organic or conventional? It's a choice many grocery shoppers are faced with, over and over. The price difference is easy to see; it's right there on the product. The quality difference is much murkier. Is organic milk better for your kids? Is conventional lettuce more likely to carry pathogens? Here's a rundown of the evidence on nutrition and contamination levels for organic and conventional products.

MILK
Nutrition: Compared with conventional 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. (It takes 11 quarts of organic milk to equal the omega-3s in four ounces of salmon.)

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.

Hormones: Many conventionally raised dairy cows, unlike organic ones, are injected with bovine growth hormone to increase milk production. The problem isn't the hormone but rather a compound called insulin-like growth factor (IGF-I). Both organic and conventional cows have IGF-I in their milk, but cows that get hormone treatment may have more of it. Some research has linked IGF-I to cancer. The American Cancer Society decided in 2011 the evidence is inconclusive.

Bottom line: Exposure to pesticides, contaminants or hormones is not a significant risk in either organic or conventional milk.

PRODUCE
Nutrition: Many studies have compared the vitamins, minerals, macronutrients and other compounds in organic and conventional produce, and a 2012 review concluded that the results were all over the map. Phosphorus content in organic produce is higher, although it's "not clinically significant." Phosphorus helps build strong bones and teeth.

Contamination: There is widespread agreement that organic produce, while not pesticide-free, has lower residue levels and fewer pesticides. But the Environmental Protection Agency has found that lifetime risk of adverse health effects from low-level exposure to pesticide residue on produce is far below even minimal health concerns. Snap beans, watermelon, tomatoes and potatoes are likely to have higher residues. If you're pregnant or feeding small children, you may want to consider organic versions of those foods. The best strategy to reduce risk from produce isn't to buy either organic or conventional. Rather, it's to thoroughly rinse and cook your food. It's worth noting that leafy vegetables, led by lettuce and spinach, are the No. 1 cause of food-borne illnesses.

MEAT

Nutrition: Some organic meat and poultry have more healthy omega-3 fats 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.

Contamination: 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 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. The risk in meat overall was essentially the same. With either organic or conventional meats, the solution is adequate cooking.

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 probably too small to affect human health.

EGGS
Nutrition: As with milk and meat, levels of the omega-3 fatty acids in eggs are affected by the hens' diet and can be increased by pasturing or diet supplementation for either organically raised or conventionally raised hens. Eggs high in omega-3s generally say so on the label.

Bottom line: There are no significant differences affecting health between organic and conventional eggs.

SEAFOOD

Nutrition: The U.S. Department of Agriculture has not issued any organic standards for farmed fish or shellfish, but several overseas organizations have. One reason is this: Because there's no way to control the diet of wild fish, "organic" doesn't apply.

Contamination: Canadian standards prohibit antibiotics and hormones, restrict pesticides and set criteria for acceptable feed. Thus far, the U.S. does not have any such criteria or standards.

Bottom line: There's not enough research comparing so-called organically fed and conventionally raised and fed fish to draw any conclusions about their health benefits.