The nerves of the body that are not part of the brain or spinal cord are known as peripheral nerves. Damage or dysfunction of these nerves is referred to as neuropathy. When neuropathy affects both feet or both hands, it is often called a polyneuropathy, also known as a “stocking and glove” pattern. Symptoms may include pain, numbness, tingling, burning, weakness, or loss of sensation, although some people have no noticeable symptoms and are diagnosed through physical examination or testing such as electromyography (EMG) or nerve conduction velocity (NCV) studies. Peripheral neuropathy is especially common in people with diabetes.
A randomized, double-blind, placebo-controlled study published in Zhonghua Yi Xue Za Zhi (2007 Oct 16;87(38):2706–2709) examined the effects of alpha-lipoic acid supplementation on diabetic polyneuropathy. The study included 460 patients with diabetes who had mild to moderate distal symmetric sensorimotor polyneuropathy. Participants received either a placebo or 600 mg per day of alpha-lipoic acid for up to four years. Fasting plasma glucose, fasting insulin, supersensitive C-reactive protein (sCRP), and HbA1c were measured, and neurological symptoms were evaluated using the Total Symptom Score (TSS) and the Michigan Neuropathy Screening Instrument (MNSI).
Fifty patients in the treatment group and forty-three in the control group completed the study. Compared with the control group, the TSS in the alpha-lipoic acid group was significantly reduced after one week, although the MNSI score did not change at that point. After fourteen days, both TSS and MNSI scores were significantly lower in the treatment group compared with controls. Symptoms of numbness, tingling, and burning were significantly reduced after two weeks of alpha-lipoic acid treatment, while no meaningful symptom changes were seen in the placebo group. The overall satisfaction rate was 90% in the treatment group, compared with 13.95% in the control group. One patient experienced chest discomfort during intravenous administration, which resolved when the infusion rate was slowed, and no other significant adverse effects were reported.
Additional research supports these findings. A study published in Experimental Neurology (2008 Dec;214(2):276–284) found that alpha-lipoic acid reduced nerve damage following chemotherapy. A review published in Diabetes Educator (2007 Jan–Feb;33(1):111–117) concluded that alpha-lipoic acid was effective in improving symptoms of diabetic neuropathy. Earlier research published in Diabetes (1997 Sep;46 Suppl 2:S62–S66) reported that intravenous alpha-lipoic acid at 600 mg per day for three weeks was safe and effective for reducing symptoms of diabetic peripheral neuropathy, and that oral dosing of 800 mg per day for four months may improve cardiac autonomic dysfunction in people with type 2 diabetes.
