Purpose of review
This review aims to address the latest research on hepatic desaturases and metabolic disorders, with focus on stearoyl-CoA desaturase-1 (SCD-1) indices in observational studies.
In animal studies, SCD-1 inhibition protects against features of the metabolic syndrome and is associated with improved hepatic insulin resistance and decreased steatosis. In human observational studies, higher estimated hepatic SCD-1 and Δ6-desaturase activities predict the metabolic syndrome, insulin resistance and mortality whereas Δ5-desaturase index is often inversely related. However, because the desaturase activities in the liver and adipose tissue may not be regulated in parallel, it is important to define used lipid fractions when comparing studies. It is also important to take the background diets of the populations into account when comparing studies. Moreover, there may be a divergence in desaturase regulation depending on glycaemic control among individuals.
Increased SCD-1 indices reflecting liver desaturase activity have been associated with insulin resistance, fatty liver, the metabolic syndrome and mortality. However, it remains to be determined if high hepatic SCD-1 activity plays a direct role in the development of metabolic disorders or rather is a marker for an unfavourable diet or hepatic insulin resistance.