Linolenic acid is a polyunsaturated omega-3 fatty acid with 18 carbons and three double bonds. Current recommendations for omega-3 fatty acids suggest a minimum of 0.5 percent of calories from omega-3 fatty acids with 10 calories of pure alpha-linolenic acid, according to Kathleen Mahan and Sylvia Escott-Stump in "Krause's Food, Nutrition, & Diet Therapy." In a 2,000-calorie diet, this recommendation could be met with 2 tsp. flaxseed, 3 tbsp. walnuts or 1 tbsp. canola or soybean oil. Linolenic acid benefits the heart by decreasing the risk of abnormal heartbeats, decreasing triglyceride levels and slowing the growth of plaque in the arteries.
Breast Milk and Infant Formula
Breast milk and infant formulas contain a generous proportion of both linolenic and linoleic acid. These are among the lipids that provide the main source of energy in the infant's diet. Breast milk contains 55 percent fat compared to infant formula which contains 49 percent fat. Five percent of the calories in human milk and 10 percent in most infant formulas are derived from linoleic or omega-6 fatty acid, and smaller amounts from linolenic or omega-3 fatty acid.
Omega-3 fatty acids are found in olive oil, canola oil, safflower oil, corn oil and soybean oil, according to Eleanor Whitney and Sharon Rolfes in "Understanding Nutrition." Stir-fry with small amounts of these oils or use as salad dressings to increase linolenic acid intake.
Nuts and Seeds
Add crushed flax seed to salads and entrees to take advantage of the richest source of alpha-linolenic acid. Eat butternuts, walnuts, soybean kernels, red and black currant seeds, pumpkin seeds and sesame seeds as snacks or added to salads.
Consume soybeans and products made from soy to increase your linolenic acid intake. Soy milk, tofu and soy-based meat alternatives also help boost your omega-3 fats.
Fish and Other Animal Products
To obtain the right balance of omega-3 and omega-6 fatty acids, most people need to eat more fish and less meat, according to "Understanding Nutrition." The best animal source of omega-3 fatty acids is fish such as salmon, sardines, mackerel, tuna, anchovies, lake trout and herring. The American Heart Association recommends two servings of these fatty fish per week. Hens that feed on flaxseed produce eggs rich in omega-3 fatty acids. Other animal sources such as beef tallow, butter and lard contain small amounts of omega-3 fatty acids but also contain mostly saturated fat.