Abstract Body (Do not enter title and authors here): Background:
5-Hydroxytryptophan (5-HTP) has shown positive clinical effects on various neuropsychiatric and metabolic disorders, particularly depression. While it is known to increase serotonin levels in the brain and gastrointestinal tract, its pharmacology remains largely unexplored. Additionally, 5-HTP influences the mouse gut microbiome, which is closely linked to depression through the "microbiota-gut-brain axis." However, the role of 5-HTP in vascular disease is not well understood. This study aimed to investigate the potential correlation between serum 5-HTP levels and the severity of coronary artery calcification (CAC) in patients with acute coronary syndrome (ACS).

Methods and Results:
This study included 183 ACS patients who underwent coronary angiography. The severity of coronary calcification was recorded, and serum 5-HTP levels were measured after the coronary event. The study period was from February 4, 2009, to August 9, 2020. The primary exposure variable was 5-HTP levels, and the primary outcome was the severity of coronary calcification assessed through fluoroscopy. Logistic regression was used to determine the association between 5-HTP levels and calcification severity, adjusting for age, gender, smoking status, chronic kidney disease, hyperlipidemia, and diabetes. Odds ratios (OR) and 95% confidence intervals (CI) measured the strength of associations, with statistical significance set at p < 0.05.

High 5-HTP levels were significantly associated with more severe calcification (p = 0.04, OR = 3.3, 95% CI = 2.6 to 40686.5). For other factors, the OR for smokers was 0.97 (0.53 to 1.77); dyslipidemia 0.91 (0.5 to 1.63); hypertension 1.57 (0.87 to 2.82); male gender 1.35 (0.45 to 4.01); age 1.07 (1.03 to 1.10); diabetes 1.24 (0.67 to 2.31); chronic kidney disease 1.07 (0.33 to 3.50). After adjusting for conventional risk factors, the association between 5-HTP and calcification remained significant (p < 0.05).

Conclusion:
Higher 5-HTP levels are positively associated with greater severity of coronary artery calcification. This correlation persists even after adjusting for conventional risk factors.