Generally, the walnuts you see on your supermarket shelf are the English variety. Easy to crack open, they add taste and texture to cookies, cakes, yogurt, cereal and oatmeal, salads and vegetables. Harder-to-find black walnuts have a bold, earthy flavor and require a lot of work to get them out of their shells. They’re difficult to hull, and the husks can stain your hands. Both, however, offer plenty of nutritious benefits.
English walnuts, or Juglans regia, derive from the Middle East and are so-named because British merchants sold them throughout the world. In the 1700s, Spanish missionaries started growing walnut trees in California. Today, 99 percent of English walnuts sold in the United States -- and two-thirds of those sold in the world -- come from the San Joaquin and Sacramento Valleys. Black walnuts, or Juglans nigra, originate in the United States, where they grow wild. They are much less cultivated than are English walnuts.
A major benefit of eating walnuts is a healthy dose of omega-3 polyunsaturated fats. Walnuts contain alpha-linolenic acid, or ALA, the plant-based source of omega-3 fats. A steady diet of these omega-3 fats helps lower blood pressure and bad cholesterol, decrease inflammation, prevent blood clots, strengthen bones, increase cognitive function and lower risk of heart disease, cancer, diabetes and metabolic syndrome. Although they’re high in calories, walnuts can actually help you lose weight because they are low in saturated fats and high in fiber.
English Walnut Nutrition
From a handful of English walnuts, about 1 ounce or seven whole ones, you get 190 calories, 4 grams of protein and 2 grams of fiber, along with high amounts of vitamin E, potassium, copper, phosphorus and magnesium, according to the California Walnut Commission. You can buy them unshelled, halved or in broken pieces.
Black Walnut Nutrition
One ounce black walnuts contains about the same amount of calories, protein and fiber. Also high in potassium, magnesium, phosphorus and vitamin E, black walnuts have less omega-3 than do English walnuts, but more arginine and selenium, according to the University of Missouri Center of Agroforestry. Often handpicked in the wild, black walnuts are a popular ingredient in ice cream. They are more expensive than English walnuts.
Since the polyunsaturated fat in walnuts can oxidize quickly, store walnuts in the refrigerator or freezer in an airtight container.