With Thanksgiving just around the corner, many people connect their post-feast drowsiness to the amino acid tryptophan found in turkey. But how does tryptophan make you feel sleepier and more relaxed? It turns out tryptophan is not only known for causing those cozy post-meal naps but also for being a precursor to Vitamin B3, serotonin and, ultimately, melatonin. Melatonin is a “chill-out” hormone that can indeed make you sleepy.
But here’s the twist: Apart from its role in inducing that post-Thanksgiving drowsiness, tryptophan’s metabolism in your gut has been linked to a range of health conditions. These include inflammatory bowel disease, metabolic disorders, chronic kidney disease and even cardiovascular issues. So, while you might feel like napping after eating foods that contain tryptophan, there’s a lot more to this molecule than meets the eye.
Tryptophan—also found in chicken, tofu, eggs, milk and oats—plays a pivotal role within the gastrointestinal system. One study has found that the bacteria living in your gut actively generate three key compounds, derived from the breakdown of tryptophan, that are involved in maintaining gut barrier health. A diet rich in tryptophan has been shown to protect mice from colitis treatment by reducing inflammation and preventing death.
Researchers have also looked at what happens when you cut back on tryptophan in your diet. They discovered some intriguing findings. Researchers saw that feeding older mice a low-tryptophan diet led to a decline in levels of beneficial bacteria in the gut. One example of beneficial bacteria is called Clostridium sporogenes, which is responsible for processing tryptophan and producing valuable substances such as serotonin.
Serotonin is a “feel good” chemical messenger that helps stabilize your mood but also plays a role in digestion, sleep and wound healing, among other things. On the flip side, the researchers noticed the mice had three times as much Acetatifactor, a bacterium associated with gut inflammation. As a result, the mice experienced higher levels of intestinal inflammation. So, it turns out, tryptophan plays a pretty crucial role in keeping your gut’s ecosystem in balance.
As you indulge in your Thanksgiving feast, remember that the tiny bacteria and fungi in your gut play an important part in tryptophan metabolism. They work tirelessly to break down this essential amino acid, contributing to and maintaining a healthy environment where all bacteria thrive to create a robust, well-balanced gut.
Raz Abdulqadir is a PhD candidate in the biomedical science program at Penn State College of Medicine. Her research examines the role of probiotic-host interactions on the modulation of the intestinal epithelial tight junction barrier.