Résumé : To evaluate the effect of oral supplementation with magnesium chloride on the systemic and hepatic inflammation, 38 non-hypertensive obese women aged 30 to 65 years were allocated into groups with and without hypomagnesemia. Hypomagnesemic women drank 50 mL of 5% solution of MgCl
2 equivalent to 450 mg of elemental magnesium. Low-carbohydrate diets and physical activity were indicated for women in both groups. Chronic diarrhea, alcohol intake, use of diuretics, previous oral magnesium supplementation, hepatic disease, and renal damage were exclusion criteria. Hypomagnesemia is defined by serum magnesium concentrations ≤ 1.8 mg/dL, hepatic inflammation by serum alanine aminotransferase (ALT) levels ≥ 40 U/L, and systemic inflammation by serum high-sensitivity C reactive protein (hs-CRP) concentration ≥ 3 mg/L. At baseline (p = 0.06) and final of follow-up (p = 0.80), there were no significant differences by body mass index between the groups in the study. In the same way, at baseline ALT (48.1 ± 25.5 and 34.6 ± 24.1 U/L, p = 0.14) and hs-CRP (9.4 ± 6.0 and 7.9 ± 5.9 mg/dL, p = 0.47) levels were similar in the supplemented and non-supplemented women. In the magnesium group, ALT (24.3 ± 10.3 and 34.8 ± 13.6 U/L, p = 0.02) levels, but not hs-CRP (5.2 ± 1.9 and 8.0 ± 5.6 mg/L, p = 0.08) reached significantly lower levels, in the fourth month of treatment, than in women in the control group. The adjusted odds ratios between the improvement in serum magnesium and reduction in ALT and hs-CRP levels were 0.56 (95% CI: 0.3-0.9) and 0.93 (95% CI: 0.6-29.9), respectively. Results of this study show that in hypomagnesemic obese women, oral supplementation with magnesium chloride reduces plasma ALT levels; hs-CRP levels only show a reduction trend.