The Effect of the Gluten-Free Diet on the Metabolic Activity of the Intestinal Microbiota in Patients with Celiac Disease

The aim is to study the effect of the gluten-free diet (GFD) on the spectrum of short-chain fatty acids (SСFAs) in the intestine in patients with celiac disease. Material and methods. 61 patients with celiac disease were examined, confirmed by positive serological tests and histological examination of the mucous membrane of the small intestine. Men were 17 (13.7%), median age – 41 years; women – 44 (86.3%), median age – 45 years. The first group included patients with newly diagnosed celiac disease (n = 21); the second group included patients who observe GFD, consciously or unconsciously violate it (n = 20); the third group consisted of patients who strictly observe GFD (n = 20). The duration of dietary treatment of patients of the second group ranged from two hundred months to seven years, in patients of the third group – from one year to eight years.The level of SСFAs in feces was determined by gas-liquid chromatography on the Crystal 2000 M chromatograph. The control group consisted of 22 healthy volunteers, among them were 6 (27.3%) men, 16 (72.7%) women, the median age was 42 years (Q1-Q3: 32–58 years; Shapiro p-value < 0.01). Statistical analysis was performed using parametric and nonparametric methods according to the Statistica 13.3 program (StatSoft Inc., USA). Results. The total level of SCFAs in the coprofiltrate of patients of the first group was slightly higher than in the control group (13.15 ± 1.52 vs 9.8 ± 2.1 mg/g; p = 0.278), the anaerobic index was significantly higher (1.43 ± 0.23 vs 0.754 ± 0.15 mg/g; p = 0.017), which indicated an increase in the metabolic activity of anaerobic bacteria. Significant differences in patients of the first group and in the control group were obtained in the levels of propionic acid (3.85 ± 0.62 vs 1.65 ± 0.46 mg/g; p = 0.006); isobutyric acid (0.67 ± 0.1 vs 0.28 ± 0.1 mg/g; p = 0.009) and valerian acid (0.83 ± 0.13 vs 0.32 ± 0.09 mg/g; p = 0.002). In patients of the second group, a significant decrease in the total amount of SCFAs was found compared with the control group (4.6 ± 0.9 vs 9.8 ± 2.1 mg/g; p = 0.034). Also, in the second group, compared with the control group, a significant decrease in the concentration of acetic acid was revealed (1.9 ± 1.2 vs 5.36 ± 1.1 mg/g; p = 0.045). The level of isovaleric acid was increased in the second group compared to the third group (0.66 ± 0.14 vs 0.22 ± 0.13 mg/g; p = 0.04), and the level of capronic acid concentration was reduced (0.05 ± 0.1 vs 0.35 ± 0.1 mg/g; p = 0.04). These data indirectly indicated a decrease in the number of representatives of the saccharolytic microflora in the second group. Conclusion. When studying the spectrum and concentration of SCFAs in the feces of patients with celiac disease who are at different stages of treatment of GFD and recovery of MMSI, there is a tendency to multidirectional metabolic activity of the colonic microbiota. As the GFD is observed, the overall level of SCFAs decreases, there is a shift in the ratio of anaerobes and aerobic bacteria, the level of isovaleric acid increases and the tendency to increase isobutyric acid decreases, the level of acetic and caproic acids decreases. To optimize the treatment of patients with celiac disease, further monitoring of the metabolic activity of the intestinal microbiota in the process of dynamic observation is required.