Black walnuts, or Juglans nigra, are one of the three major types of walnuts. Black walnuts have a thicker shell and a richer, more pungent and distinctive flavor than English walnuts, which are the most popular and widely consumed type of walnut in the U.S. Black walnuts are rich in minerals as well as a type of health-promoting unsaturated fat known collectively as omega-3 fatty acids.
Rich in Minerals
Black walnuts are high in minerals -- nutrients essential in small quantities for human health -- including magnesium, phosphorus, copper and manganese. A 1-oz. serving meets about 14 percent of the recommended daily value for magnesium and phosphorus, 19 percent of the DV for copper and 55 percent of the DV for manganese, according to the U.S. Department of Agriculture.
Magnesium is a mineral important for maintaining strong, healthy bones, regulating blood pressure and aids in muscle relaxation. Thus, magnesium may reduce your likelihood of experiencing tension and migraine headaches. Phosphorus, along with calcium and magnesium, is needed for developing strong bones and teeth, as well as proper growth. Manganese aids in bone formation and plays a role in the metabolism of protein, fat and carbohydrates, whereas copper works with iron to form hemoglobin. It is also required to manufacture collagen.
Anti-Inflammatory
A 1-oz serving of black walnuts, according to the World's Healthiest Foods website, provides 560 mg of a type of short-chain omega-3 fatty acid known as alpha-linolenic acid. Walnuts are the richest source of ALA of any nut. The human body can convert ALA into a more potent and longer chain omega-3 fatty acid known as eicosapentanoic acid or EPA. A study published in the American Journal of Clinical Nutrition in July 2009 reports that consumption of nuts, particularly walnuts, is associated with a decreased risk of cardiovascular disease and death. In addition to improving blood cholesterol levels, omega-3 fatty acids protect the heart by lowering levels of C-reactive protein, a marker of inflammation that is strongly associated with the development of atherosclerosis.
Slows Cognitive Decline
According to research published in the Journal of Nutrition in July 2009, walnuts and berries appear to play a significant role in preventing and/or decreasing the risk of age-related disorders that impair brain function. According to study author J. Joseph, PhD, old rats that were fed diets composed of two, six or nine percent walnuts improved several markers of brain aging as well as age-related cognitive deficits. For humans, a 6 percent walnut diet would be the equivalent of consuming 1-oz. daily. When high antioxidant foods, such as Concord grapes, berries and walnuts are consumed together, this increases the "health span" of the brain and offers a more impressive effect on cognitive and motor function in aging.
References
- U.S. Department of Agriculture: Nutritional Information on Nuts, walnuts, black, dried
- NutritionValue.org: Nuts, walnuts, black, dried
- MayoClinic.com: Nutrition and Healthy Eating--What does Percent Daily Value mean on food labels?
- Australian Government: Department of Health and Aging - Vitamin and Mineral Functions
- "American Journal of Clinical Nutrition"; Effects of walnut consumption on blood lipids and other cardiovascular risk factors: a meta-analysis and systematic review; DK Banel et al.; May 2009
- "Journal of Nutrition"; Grape juice, berries, and walnuts affect brain aging and behavior; J. Joseph PhD et al.; Jul 2009
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