Background:It has been shown the methylenetetrahydrofolate reductase (MTHFR) 677TT (rs 1801133) genotype predicts histopathological alterations in the incisura of patients with chronic atrophic gastritis (CAG). MTHFR is a crucial enzyme in fatty acid (FA) metabolism. This study aimed to evaluate the influence of FA supplementation in CAG patients withoutHelicobacter pyloriinfection and the MTHFR C677T (rs 1801133) genotype as a potential CAG predictor.Methods:A total of 96 CAG patients, aged 21 to 72 years old, were enrolled in this study. After 6 months of treatment, histopathological outcomes were compared among patients treated with weifuchun (WFC) (1.44 g 3 times per os per day), those treated with WFC and FA (5 mg once daily), and those treated with WFC, FA, and vitamin B12 (VB12) (0.5 mg 3 times per day) based on the Operative Link on Gastritis/Intestinal Metaplasia assessment staging systems.Results:Atrophic lesions in patients treated with WFC and FA improved more than in patients treated only with WFC therapy (78.1% vs 53.3%,P= .04). Atrophic or intestinal metaplasia (IM) lesions in the incisura of patients with the TT genotype were better than those in patients with the CC/CT genotype (P= .02).Conclusion:The treatment of CAG patients with 5 mg of FA supplements daily for 6 months improved their gastric atrophy status, especially for the Operative Link on Gastritis/Intestinal Metaplasia assessment stages I/II. Moreover, our study is the first to reveal that patients with the MTHFR 677TT genotype require more timely and effective FA treatment than those with the CC/CT genotype.