If you obtain more of your protein from plant foods like beans, seeds and nuts and less from meat, you'll significantly reduce your risk of dying from heart disease, according to studies published in the April 2012 issue of the "Archives of Internal Medicine." Nuts like walnuts and pecans are rich in a variety of essential nutrients. Although nuts are good for you, they are high in calories, cautions the American Heart Association. Aim for about four 1 1/2-ounce servings of nuts a week.

English walnuts, the most common type of walnuts in the United States, contain 18 grams of fat, 1.7 grams of saturated fat, 2.5 grams of monounsaturated fat and 13 grams of polyunsaturated fats. Raw pecans have more total fat and monounsaturated fat per ounce than walnuts -- 20 grams of fat and 11 grams of monounsaturated fat -- although they have the same amount of saturated fat and less polyunsaturated fat. Walnuts are one of the richest plant-based sources of alpha-linolenic acid, or ALA, a fatty acid that your body can convert into the heart-healthy omega-3 fatty acids, DHA and EPA. Walnuts have 9 grams of ALA in every 100-gram serving, while pecans have just 1 gram in the same serving size.

A 1-ounce serving of both walnuts and pecans provide about the same amount of total carbohydrates: 3.9 grams. They also don't differ much when it comes to dietary fiber or simple sugars. Walnuts have 1.9 grams of fiber and 0.74 grams of sugar in every 1-ounce serving. Pecans provide slightly more, with 2.7 grams of dietary fiber and 1.1 grams of sugar per 1-ounce serving.

Both walnuts and pecans are high in protein. Each 1-ounce serving of walnuts has 4.3 grams of protein, while a 1-ounce serving of pecans has 2.6 grams. An adult woman will obtain 9.3 percent of her daily protein requirement from 1 ounce of walnuts and 5.6 percent from pecans. A man will obtain 7.6 percent of the protein he needs each day from 1 ounce of walnuts and 4.6 percent from 1 ounce of pecans.

Walnuts and pecans are both sources of B vitamins, although they each contain concentrations of different nutrients from the same family of vitamins. Walnuts are richer in vitamin B-6, with each ounce containing 0.15 milligrams of the vitamin, or 11.5 percent of an adult's recommended daily intake. Pecans have more thiamin, also known as vitamin B-1, containing 0.18 grams in every ounce, which is 15 percent of a man's recommended daily intake and 16 percent of a woman's.

You can get a wide variety of minerals from both walnuts and pecans. Walnuts are especially rich in copper with 450 micrograms in every ounce; that's equivalent to about 50 percent an adult's daily recommended intake. Pecans are an excellent source of both manganese and copper. A single ounce of pecans provides 52 percent of a man's daily manganese requirement and 66 percent of a woman's.