# Can supplementation of tryptophan in parenteral nutrition increase melatonin and alleviate inflammatory response?

## TL;DR

This study investigates whether adding tryptophan to parenteral nutrition affects melatonin levels and inflammation after major abdominal surgery.

## Contribution

The study explores the potential anti-inflammatory effects of tryptophan supplementation in parenteral nutrition.

## Key findings

- Tryptophan levels were higher in the experimental group but not statistically significant.
- Melatonin levels increased in both groups post-surgery, with a significant increase in the experimental group on day 3.
- Interleukin-1 levels showed the greatest difference between groups on postoperative day 3.

## Abstract

Endogenous melatonin is produced from tryptophan which is an essential amino acid. Besides its role in the regulation of sleep patterns, melatonin has anti-inflammatory effects. In this case-control study, we aimed to compare tryptophan and melatonin levels and their relationship with the inflammatory response, specifically serum interleukin-1, interleukin-6, and c-reactive protein levels following major abdominal surgery in patients with food restriction and who receive parenteral nutritional therapy.

We enrolled 40 patients between the ages of 18 and 65 years in the study. We collected blood and urine samples 48 h before the operation and on postoperative days 1, 3, and 5.

The tryptophan levels in the experimental group were higher than in the control group but failed to reach any statistical difference. Melatonin levels were increased in both groups following the surgery compared with preoperative levels. The increase in the experimental group was statistically different 3 days after the surgery. The difference in the level of interleukin-1 between the control and the experimental groups was greatest on postoperative day 3. On postoperative day 3, the interleukin-6 level in the treatment group was slightly higher than in the control group. We did not find any difference in the levels of c-reactive protein between the groups. As a result, the levels of tryptophan and melatonin were increased in the parenteral nutrition group, irrespective of the postoperative inflammatory response.