Effects of Alpha-Lipoic Acid Supplementation in Peripheral Arterial Disease: A Pilot Study

OBJECTIVE: To examine whether 3 months of lipoic acid (LA) supplementation improved walking tolerance and delayed claudication pain onset in peripheral arterial disease (PAD). DESIGN: Randomized, double-blind, controlled study. SETTING: General Clinical Research Center. SUBJECTS: Twenty-eight (28) participants (15 men, 13 women) with PAD (ankle brachial index range 0.9-0.4, mean age 73.2 +/- 1.6 years). INTERVENTION: LA (600 mg/day) or placebo for 3 months. OUTCOME MEASURES: Walking tolerance was assessed by 6-minute walk test distance, 4-meter walk time, initial claudication pain time (ICT) and distance (ICD), and peak claudication pain. Serum was assessed for inflammation (C-reactive protein [CRP]) and oxidative stress (lipid hydroperoxides) as potential mechanisms for changes in walking tolerance. RESULTS: ICT increased 34.4% and 15%, ICD was reduced by 40.5% and 18%, and peak claudication pain ratings were reduced by 93% and 7% in LA and placebo groups, respectively. Although the improvements in peak pain and ICT achieved significance within the LA group (both p<0.05), the interactions of group by time were not found to be significant (p>0.05). Oxidative stress and CRP measures were not different between groups by month 3 (p>0.05). There were no serious side-effects associated with the LA. CONCLUSIONS: LA may confer pain relief during exercise. However, longer and larger trials are warranted to determine long-term effects of LA alone or combined with other interventions on PAD symptoms.