Fish is still your best bet for omega-3s. While organ meats, like liver, do have some omega-3s, you can't rely on them to give you all you need.
Walnuts can provide the omega-3 known as ALA, which your body doesn't make. ALA is also found in:
- some vegetable oils, especially flaxseed oil
- green vegetables like kale or spinach
Your body can turn ALA into small amounts of two other types of omega-3s, EPA and DHA. These are the kinds of omega-3s found in fish. There's more proof that they protect against heart disease.
Vegetarians and vegans can look at algae oils as a source of omega-3s.
None of these substitutes packs the omega-3 power of fish.