Moreover, our data imply that timely initiation of this intervention may be crucial to prevent disease progression and point to an important role of the gut as a primary target organ of the physiological and pharmacological actions of vitamin D. A randomized placebo-controlled pilot study conducted by our group within the Swiss Association for the Study of the Liver (SASL) network has recently reported beneficial effects of vitamin D treatment on serum ALT levels in patients with histologically defined NASH [55]. Here, GPT is linked to metabolic dysfunction-associated steatohepatitis.