Diabetes currently affects more than 100 million people worldwide, 30 million in the U.S. alone. Of this number, 1.25 million American adults and children have type-1 diabetes and another 7.2 are unaware that they even have the disease. (1) This condition is characterized by elevated levels of glucose in the bloodstream. In type-1 diabetes, formerly known as juvenile diabetes because it appears early in life, the pancreas fails to produce enough insulin to help transport glucose to muscle and other tissue where it is used as fuel for energy. In type-2 diabetes, or diabetes mellitus, the pancreas may produce sufficient insulin but the body no longer recognizes or uses it properly. The result is the same – high blood sugar. Without enough energy, cells starve and eventually die. Without intervention, significant damage may occur to the nerves, heart, eyes and kidneys.
The goal of pharmaceutical therapies for diabetes is to reduce serum glucose levels by inhibiting an enzyme called alpha-amylase, which would otherwise facilitate the digestion of carbohydrates (starch). Currently, peptides and proteins that act as alpha-amylase inhibitors are obtained from plants in the legume family, like the white kidney bean. Others, like acarbose, a prescription drug used to treat type-2 diabetes, are synthesized from bacteria, such as actinoplanes utahensis. However, these medicines can produce unwanted side effects, like cramping and diarrhea, due to excess undigested starch in the colon. For this reason, scientists are actively studying hundreds of plants that exhibit alpha-amylase blocking activity for therapies with a greater effectiveness and safety profile.
According to one Iranian study, two promising candidates are stinging nettle (Urtica dioica) and English walnut (Juglans regia). At a concentration of 0.4 mg/ml of nettle leaf extract and 2.0 mg/ml of walnut leaf extract, the extracts showed a 60% inhibition of alpha amylase activity in vitro after 30 minutes. (2)
More recently, researchers have found that, in addition to hypoglycemic properties, walnut leaf exact appears to exert antioxidant and anti-inflammatory effects that may offer protection against the development of diabetic peripheral neuropathy, as well as improve symptoms after the onset of neuropathy. (3)
1. American Diabetes Association: Statistics About Diabetes http://www.diabetes.org/diabetes-basics/statistics/
2. Rahimzadeh M, Jahanshahi S, Moein S, Moein MR. Evaluation of alpha-amylase inhibition by Urtica dioica and Juglans regia extracts. Iran J Basic Med Sci 2014; 17:465-469. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4137939/
3. Nasiry D, khalatbary AR, Ahmadvand H, et al. Protective effects of methanolic extract of Juglans regia L. leaf on streptozotocin-induced diabetic peripheral neuropathy in rats. BMC Complement Altern Med. 2017; 17: 476. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5625610/