Mineral Properties and Dietary Value of Stinging Nettle (Urtica dioica L.) Grown as a Specialty Vegetable

Stinging nettle (Urtica dioica L.) is a species with a long history of usage in all regions of the world. Currently it is receiving renewed research attention as an alternative source of textile-grade fiber, and for clinically proven medicinal and nutraceutical applications. In many cultures, nettle is also eaten as a leafy vegetable and is recommended as a substitute for spinach in recipes. The Alternative Crops Program at Virginia State University (VSU) is working to establish U. dioica agronomic and husbandry requirements as a first step towards exploring its economic potential. The present study focused on nettle yield (edible portion) and processing effects on nutritive and dietary values. Actively growing shoots were sampled from experimental plots at the VSU Randolph Farm and leaves separated from stems. After rinsing in tap water, leaf portions (200g) were further processed by blanching (1 min at 96 to 98 °C), or cooking (7 min at 98 to 99 °C) with or without salt (5 g·L^-1). Samples were cooled in ice water immediately after cooking and kept in frozen storage prior to analysis. Proximate composition, mineral, amino acid, and vitamin contents were determined following Association of Official Analytical Chemists (AOAC) methods, and nutritive value (% Daily Values) was estimated based on 100 g serving portions in a 2000 calorie diet. Results show that processed nettle can supply 80–100% of Vitamin A (including Vitamin A as ß-carotene). One of our objectives is to have it documented as a low-calorie nutritious food beneficial to human health and a valuable source of minerals and vitamins in vegetarian and other specialized diets.