Walnuts are the fruits of walnut trees and are grown all over the world. The two most well known varieties of walnuts are English walnuts and black walnuts. Walnuts have a thick outer shell and the nuts are plump, crisp and meaty. Walnuts are available year-round at most grocery stores and are most often sold shelled. Walnuts have a rich, distinctive flavor and are a source of dietary fats, protein, vitamins and minerals. A 1-oz. serving of walnuts, which is about 14 halves, has 185 calories.
Walnuts provide protein, which is essential for the growth and repair of all your body's tissues, cells and organs. A 1-oz. serving of walnuts has 4.32 g of protein. Men need 56 g of protein daily and women need 46 g, as recommended by the Institute of Medicine. Walnuts contain incomplete protein, meaning one or more essential amino acids are missing.
Walnuts are very high in fat, providing 18.5 g per 1-oz. serving. Walnuts are a very good source of alpha-linolenic acid, an omega-3 fatty acid that reduces inflammation and the risk of degenerative diseases such as heart disease and cancer. Walnuts also contain omega-6 fatty acids and monounsaturated fats. Adults should consume between 20 and 35 percent of their total daily calories from fats, as recommended by the Institute of Medicine.
Walnuts are a good source of the B vitamin, folate. Folate is essential for the synthesis of red blood cells and DNA and helps prevent anemia. A 1-oz. serving of walnuts provides 28 mcg of folate. Adults need 400 mcg of folate daily, as recommended by the Institute of Medicine. Walnuts are also a good source of vitamin B6, a water-soluble vitamin necessary for carbohydrate, protein and fat metabolism. Walnuts provide small amounts of other B vitamins including niacin, riboflavin and thiamine.
Walnuts are a source of zinc, a mineral essential for wound healing, sense of smell, immune system function and the function of many enzymes. A 1-oz. serving of walnuts has 0.88 mg of zinc. Women need 8 mg of zinc daily and men need 11 mg, as recommended by the Institute of Medicine. Walnuts are also a source of magnesium, providing 14 percent of the recommended daily amount for women and 11 percent for men.
- USDA National Nutrient Database for Standard Reference: Nuts, Walnuts, English
- University of Maryland Medical Center: Omega-3 Fatty Acids
- Institute of Medicine: Dietary Reference Intakes: RDA and AI for Vitamins and Elements
- Institute of Medicine: Dietary Reference Intakes: Macronutrients
- "Advanced Nutrition and Human Metabolism"; James L. Groff, Sareen S. Gropper; 2000