WHAT IT MEANS: Fish are often contaminated with mercury and other pollutants, and are sometimes harvested when species’ numbers are perilously low. Also, farmed-fish operations can harm wild fisheries through genetic contamination and spread of parasites and pollution. This study suggests that another choice, flaxseed oil, can also give you a boost of at least some omega-3s. And flax is likely better for the environment. “There are not that many sustainable fisheries, so flaxseed might be a good alternative,” says Laura Pagano, staff lawyer for Natural Resources Defense Council’s oceans program. Look for a flaxseed-oil brand that’s organic; add an algae supplement for that missing DHA boost. If you don’t want to take capsules, add flaxseed oil to your salad. And if you prefer to stick with fish oil, check the label to see if the oil comes from a sustainable fishery certified by the Marine Stewardship Council (MSC) or is listed “green” on the Monterey Bay Seafood Watch.