Nature's Best Isopure L-Glutamine powder has no calories, added sugars or fillers. Glutamine is the most abundant amino acid in the body and plays an important role in muscle development.* It's unflavored and perfect for stacking into your post-workout protein shake or favorite flavored beverage. All Isopure products are manufactured from the highest quality raw materials, under strict supervision and in accordance with Good Manufacturing Practices. Extensive quality control procedures ensure proper purity, dissolution and potency.