<![CDATA[Peripheral neuropathy is a common neurological complication of human immunodeficiency virus (HIV) infection. Nutritional factors, particularly vitamin B1 (thiamine), may contribute to peripheral nerve dysfunction because of their essential roles in cellular energy metabolism and neuronal function. This study aimed to investigate the associations of body mass index (BMI), dietary vitamin B1 intake, and serum vitamin B1 levels with peripheral neuropathy severity among people living with HIV. This analytical cross-sectional study included 90 patients with HIV-associated peripheral neuropathy who met the eligibility criteria. Data were obtained through medical history, physical examination, BMI assessment, dietary vitamin B1 intake assessment using a food frequency questionnaire, and serum vitamin B1 measurement. Participants were classified as having mild or moderate neuropathy. Categorical variables were analysed using the chi-square test, whereas continuous non-normally distributed variables were compared using the Mann Whitney U test. The mean age of the participants was 39.88 ± 10.46 years. Of the 90 participants, 70 (77.8%) were male. Normal BMI was observed in 40.0% of participants, while 25.6% were overweight, 20% were obese, and 14.4% were underweight. Forty-two participants (46.7%) had mild neuropathy and 48 (53.3%) had moderate neuropathy. Dietary vitamin B1 intake did not differ significantly between the mild and moderate neuropathy groups [median: 2.61 (0.44–5.99) vs. 2.46 (0.44–7.01) mg/day, respectively; p = 0.683]. Serum vitamin B1 levels were significantly higher in participants with mild neuropathy than in those with moderate neuropathy [median: 1,427.25 (417.39–3,083.42) vs. 748.60 (29.88–10,585.42) ng/mL, respectively; p < 0.001]. BMI was not significantly associated with neuropathy severity (p = 0.261). Serum vitamin B1 levels were significantly lower in participants with moderate neuropathy than in those with mild neuropathy, whereas BMI and dietary vitamin B1 intake were not significantly associated with neuropathy severity. Given the wide range of serum vitamin B1 concentrations observed, these findings do not support routine thiamine supplementation in all patients. Instead, thiamine status should be monitored and confirmed deficiencies should be appropriately treated. Prospective studies controlling for antiretroviral therapy, immune status, and other potential confounders, while incorporating measurements of thiamine diphosphate and thiamine transporters, are warranted. Keywords: HIV, peripheral neuropathy, vitamin B1, thiamine, body mass index, nutritional status ]]>
