Omega-3 fatty acids -- eicosapentaenoic acid, or EPA, and docosahexaenoic acid, or DHA -- are abundant in fish, and plants contain alpha-linolenic acid or ALA. The body needs to convert ALA to EPA and DHA to receive the full benefits, but the conversion is slow, according to Harvard School of Public Health professor Walter Willett in a 2009 U.S. News and World Report Health article. The body cannot manufacture these essential nutrients, so they must be supplied by foods. While people who eat animal products acquire omega-3 easily, vegetarians consume much less than their bodies need.
Algae and seaweed are vegetarian sources of DHA that can be used for supplementing the vegetarian or vegan diet, but DHA extracted from algae contains no EPA. The U.S. News and World Report article suggests combining DHA-rich algae with ALA-rich plant sources that the body converts into EPA to get the proper ratio of omega-3 fatty acids. Vegetarians can find algae supplements in gelatin-free capsules.
Nuts and Seeds
Some nuts and seeds contain ALA, which the body can convert into EPA, but the process is inefficient, and only a small amount is converted. You can add a handful of ALA-rich nuts and seeds, such as pumpkin seeds, flaxseeds or walnuts to your salad, yogurt or cereal to obtain some of your omega-3 fatty acids. It may be a good idea to take a plant-based omega-3 supplements containing either DHA, EPA or both. Although most omega-3 supplements are made from fish sources, vegetarian supplements are available and are derived mainly from plant sources, such as flaxseed.
Many plant and nut oils are also sources of omega-3, and by using ALA-rich oils, such as canola, soybean, olive, walnut, pumpkin, perilla and flaxseed oils, a vegetarian can obtain ALA, which the body can convert to EPA. When people obtain omega-3 from plant sources, the body converts ALA into EPA with only a small amount of DHA. To get a balance of DHA and EPA, plant-based foods should be consumed with foods or supplements that contain or produce DHA.
Vegetables and Fruits
Vegetarians looking for omega-3 fatty acids can find them in leafy green vegetables, such as spinach, kale and collard greens, and cruciferous vegetables, such as broccoli and cauliflower. These vegetables contain alpha-linolenic acid that the body can use to produce EPA. Another source of essential fatty acids is winter squash. One of the few fruits that contain more omega-3 than omega-6 fatty acid is the papaya.
Some legumes are better sources of omega-3 nutrients than others. Kidney, pinto, soybeans and the foods prepared with these beans provide more of these nutrients than chickpeas and hummus.
Some food products are now fortified with omega-3 fatty acids, but the amount of EPA, DHA and ALA varies. The Omega-3 Learning Consortium for Health and Medicine emphasizes the importance of reading labels carefully to make sure the product contains the nutrients you are looking for. Vegetarians who eat eggs and dairy products can find milk, eggs and yogurt fortified with DHA. Soy milk is naturally rich in ALA, and some soy products are fortified with DHA. Fortified orange juice and juice blends are available, but choose unsweetened juices. Just because a food product is fortified, does not mean it is healthy.