Effects of vitamin D status and supplementation on MASLD severity in individuals with overweight or obesity: a cross-sectional study and randomized controlled trial.

PURPOSE: Lifestyle modification is the cornerstone of metabolic dysfunction-associated steatotic liver disease (MASLD) management, but effective adjunctive therapies are lacking. We examined the association between serum 25-hydroxyvitamin D [25(OH)D] and non-invasive parameters of MASLD severity and evaluated whether vitamin D3 supplementation, as an adjunct to lifestyle modification, influenced these parameters in adults with overweight or obesity and MASLD.

METHODS

A cross-sectional analysis of 505 adults with overweight or obesity and MASLD assessed associations between serum 25(OH)D and non-invasive liver parameters. In a subsequent 24-week randomized controlled trial (RCT), 132 participants were randomly assigned 1:1 to the vitamin D3 group (14,000 IU/week plus lifestyle modification) or the control group (lifestyle modification alone).

RESULTS

In the cross-sectional analysis, serum 25(OH)D levels were independently and inversely associated with controlled attenuation parameter (CAP) and liver stiffness measurement (LSM) (both P < 0.001). In the RCT, the vitamin D3 group showed a greater reduction in CAP than the control group [adjusted difference = -41.2 dB/m; 95% confidence interval (CI), -56.8 to -25.6; P < 0.01]. No significant difference was observed in LSM change between the two groups (adjusted difference = -0.9 kPa; 95% CI, -2.3 to 0.4; P = 0.17).

CONCLUSION

Serum 25(OH)D levels were inversely associated with non-invasive parameters of MASLD severity in adults with overweight or obesity. Adjunctive vitamin D3 supplementation may provide an additional benefit for CAP reduction alongside lifestyle modification, whereas its effects on LSM require further investigation.

TRIAL REGISTRATION: The study was registered with the Chinese Clinical Trial Registry (ChiCTR2100044305) on 16 March 2021. https://www.chictr.org.cn/showproj.html?proj=123441 .