Hazelnuts are grape-sized nuts that grow in clusters on trees. The nuts require a mild climate until they are harvested, and their sweet kernels are covered in a hazel-colored shell.
Hazelnuts, also referred to as filberts, are used for a variety of culinary and medicinal purposes. The rich nuts are crushed, transformed into a paste or used whole in desserts, entrées and side dishes. Some people believe that the oil found in hazelnuts is an antioxidant that lowers cholesterol levels, but as of March 2015, there is insufficient evidence to support this idea. Life-threatening respiratory problems can occur in individuals with a hazelnut allergy who consume the nuts.