Four Weeks of Preoperative Omega-3 Fatty Acids Reduce Liver Volume: a Randomised Controlled Trial

Weight loss before bariatric surgery with a low-calorie diet (LCD) has several advantages, including reduction of liver volume and an improved access to the lesser sac. Disadvantages include performing surgery in a state of undernutrition, side effects, costs and patient compliance. Omega-3 fatty acids may serve as an alternative to reduce liver steatosis.

A randomised controlled open-label trial was done to compare the effects of a LCD with Modifast (800 kcal/day) during 2 weeks with 2 g of omega-3 fatty acids a day and a normal diet (2000 kcal/day) during 4 weeks. Total liver volume (TLV) and volume of the left liver lobe (LLL), visceral fat area (VFA) and muscle area (SMA) at the L3-L4 level were measured with MRI before and after preoperative treatment.

Sixty-two morbidly obese women undergoing laparoscopic Roux-en-Y gastric bypass surgery (LRYGB) were recruited. In both groups, there was a significant decrease in LLL, TLV and VFA. For LLL and TLV reduction, the LCD had a significantly larger effect (p < 0.05). Only in the LCD group was there a significant decrease in SMA with significantly more side effects and worse compliance.

Both the LCD and omega-3 diet reduced LLL, TLV and VFA. The LCD outperformed the omega-3 diet in LLL and TLV reduction, but induced significant loss of SMA and had worse compliance due to more side effects. Omega-3 fatty acids may provide a safe and more patient-friendly alternative for a LCD and further research is indicated.

The study is registered at www.clinicaltrials.gov (NCT02206256).