Hello Mayo Group, I suffered from cold hands and feet for 15 years until January, 2021. My Doc told me I had Reyes(sp) Syndrome and there was no known cause or way to lessen or cure the malady. On November 30, 2020, I learned about a fungus called and sold as Lions Mane used in Chinese medicine for nerve damaged system disorders including Small Fiber Peripheral Neuropathy. I bought a bottle from the web and took the pills for 90 days as a desperate attempt to reduce nerve damage to my toes. Instead, my cold hands and feet improved about 90% better. Now I take the Lions Mane in cold weather to ameliorate the cold hands and feet. The chemical content of the Lions Mane was analyzed by a medical researcher I know and found to contain chemicals in the fungus that can help repair nerve damage. What ever the cause, the outcome works for me and makes my winters more bearable. My wife of 48 years is especially grateful for the loss of cold hands and feet! Perhaps Mayo has some experience with this situation. Best Thanksgiving Regards.