[Clinical Importance of Non-alcoholic Fatty Liver Diseases. Topics: V. Extrahepatic manifestations: cerebral and cardiovascular diseases, chronic kidney disease]

Effects of dietary supplementation of fish oil plus vitamin D3 on gut microbiota and fecal metabolites, and their correlation with nonalcoholic fatty liver disease risk factors: a randomized controlled trial

We previously reported that fish oil plus vitamin D3 (FO + D) could ameliorate nonalcoholic fatty liver disease (NAFLD). However, it is unclear whether the beneficial effects of FO + D on NAFLD are associated with gut microbiota and fecal metabolites. In this study, we investigated the effects of dietary supplementation of FO + D on gut microbiota and fecal metabolites and their correlation with NAFLD risk factors. Methods: A total of 61 subjects were randomly divided into three groups: FO + D group (2.34 g day-1 of eicosatetraenoic acid (EPA) + docosahexaenoic acid (DHA) + 1680 IU vitamin D3), FO group (2.34 g day-1 of EPA + DHA), and corn oil (CO) group (1.70 g d-1 linoleic acid). Blood and fecal samples were collected at the baseline and day 90. Gut microbiota were analyzed through 16S rRNA PCR analysis, and fecal co-metabolites were determined via untargeted ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). Results: The relative abundance of Eubacterium (p = 0.03) and Lactobacillus (p = 0.05) increased, whereas that of Streptococcus (p = 0.02) and Dialister (p = 0.04) decreased in the FO + D group compared with the CO group. Besides, changes in tetracosahexaenoic acid (THA, C24:6 n-3) (p = 0.03) levels were significantly enhanced, whereas 8,9-DiHETrE levels (p < 0.05) were reduced in the FO + D group compared with the CO group. The changes in 1,25-dihydroxyvitamin D3 levels in the fecal samples were inversely associated with insulin resistance, which was determined using the homeostatic model assessment model (HOMA-IR, r = -0.29, p = 0.02), and changes in 8,9-DiHETrE levels were positively associated with adiponectin levels (r = -0.43, p < 0.05). Conclusion: The present results indicate that the beneficial effects of FO + D on NAFLD may be partially attributed to the impact on gut microbiota and fecal metabolites.

[Correlation between serum 25(OH) vitamin D and liver fat content in nonalcoholic fatty liver disease]

OBJECTIVE

To investigate the relationship between serum 25(OH) vitamin D and liver fat content in nonalcoholic fatty liver disease (NAFLD).

METHODS

A total of 120 patients with NAFLD admitted in our hospital between June and August, 2017 were enrolled and divided into 4 groups with different serum 25 (OH) vitamin D levels: >75 nmol/L (group A, n=25), 50-75 nmol/L (group B, n=35), 25-50 nmol/L (group C, n=32), and < 25 nmol/L (group D, n=28). For all the patients, serum 25 (OH) vitamin D level was measured by ELISA, and liver fat content was determined using in-phase opposed-phase T1WI sequences. The measurement data were compared among the 4 groups to assess the association between serum 25(OH) vitamin D level and liver fat content.

RESULTS

The liver fat content appeared to be higher in group B (28.66±6.45%) and group C (38.74±11.47%) than in group A (22.79 ± 6.10%), but the difference was not statistically significant (P>0.05); the liver fat content in group D (54.79 ± 5.28%) was significantly higher than that in the other 3 groups (P>0.05). Liver fat content increased significantly as serum 25(OH) vitamin D level decreased, showing an inverse correlation between them in these patients (P < 0.05, r=-0.125).

CONCLUSIONS

In patients with NAFLD, a decreased serum 25(OH) vitamin D level is associated with an increased liver fat content, suggesting the value of serum 25(OH) vitamin D as a predictor of NAFLD.