Effects of omega-3 polyunsaturated fatty-acid supplementation on neuropathic pain symptoms and sphingosine levels in Mexican-Americans with type 2 diabetes

PURPOSE: To determine whether dietary supplementation with omega-3 polyunsaturated fatty acids (PUFAs) reduces neuropathic pain symptoms in Mexican-Americans with type 2 diabetes. METHODS: Forty volunteers with type 2 diabetes enrolled in the “En Balance-PLUS” program, which provided weekly nutrition–diabetes education and daily supplementation with 1,000 mg docosahexaenoic acid (DHA)–200 mg eicosapentaenoic acid over 3 months. The study assessed self-reported neuropathic pain symptoms pre/postintervention using the short-form McGill Pain Questionnaire (SF-MPQ), monitored clinical laboratory values at baseline and 3 months, and performed baseline and 3-month metabolomic analysis of plasma samples. RESULTS: A total of 26 participants self-reported neuropathic pain symptoms at baseline. After 3 months of omega-3 PUFA supplementation, participants reported significant improvement in SF-MPQ scores (sensory, affective, and visual analogue scale; P<0.001, P=0.012, and P<0.001, respectively). Untargeted metabolomic analysis revealed that participants in the moderate–high SF-MPQ group had the highest relative plasma sphingosine levels at baseline compared to the low SF-MPQ group (P=0.0127) and the nonpain group (P=0.0444). Omega-3 PUFA supplementation increased plasma DHA and reduced plasma sphingosine levels in participants reporting neuropathic pain symptoms (P<0.001 and P<0.001, respectively). Increased plasma DHA levels significantly correlated with improved SF-MPQ sensory scores (r=0.425, P=0.030). Improved SF-MPQ scores, however, did not correlate with clinical/laboratory parameters. CONCLUSION: The data suggest that omega-3 PUFAs dietary supplementation may reduce neuropathic pain symptoms in individuals with type 2 diabetes and correlates with sphingosine levels in the plasma.