According to the USDA, certified organic foods are grown and processed according to federal guidelines addressing many factors such as soil quality, animal raising practices, pest and weed control, and use of additives.

Produce
Produce can be called organic if it's certified to have grown in soil that had no prohibited substances applied for three years prior to harvest. Prohibited substances include most synthetic fertilizers and pesticides. For this reason, organic produce compared to conventional produce often has higher antioxident content and reduced pesticide levels.

Meat
As for organic meat, regulations require that animals are raised in living conditions accommodating their natural behaviors (like the ability to graze on pasture), fed 100% organic feed and forage, and not administered antibiotics or hormones.

Packaged Food
Regulations prohibit organically processed foods from containing artificial preservatives, colors, or flavors, and require that their ingredients are organic (with some minor exceptions). When packaged products indicate they are "made with organic” (specific ingredient or food group), this means they contain at least 70% organically produced ingredients.

The bottom line: the "USDA Organic" designation refers to a unique set of sourcing, growing, harvesting and processing methods, and does not mean that a product is healthful or more nutrient-dense. Shoppers who want to avoid pesticides can start with the Dirty Dozen list.