Active Study Explores Link Between Tryptophan and Memory Loss

Written by: CEHD Communications Staff
Post date: November 26, 2014

As the myth goes, the drowsiness one feels after a satisfying Thanksgiving meal is caused by tryptophan – an amino acid found in turkey.

According to Dr. Nicolaas Deutz, professor at the Center for Translational Research in Aging and Longevity (CTRAL), that theory is wrong on several levels.

As he points out, drowsiness after a Thanksgiving meal is much more likely due to the quantity of food rather than the turkey itself. Also, turkey contains no more tryptophan than any other kind of poultry. In fact, he says, tryptophan can be found in almost any protein.

“This story about tryptophan in turkey is just kind of a running joke,” he insists. “It has nothing to do with the tryptophan.”

On a more practical level, he hopes that he can use the amino acid to help patients with a disease that is no laughing matter: multiple sclerosis.

In a study funded by the Maastrict University Medical Center, he explores the potential for tryptophan-enriched diets to improve the mood and cognition of patients with the debilitating disease.

Even though multiple sclerosis typically affects younger people between the ages of 20 and 50, CTRAL – a center that is focused on improving the lives of much older adults – has a special interest in studying treatments for multiple sclerosis.

“In many ways, multiple sclerosis is almost like the brain getting older on its own,” Dr. Deutz explains. “The memory problems really look similar to dementia, Parkinson’s and other diseases that affect older people.”

In the past he conducted research in which his team reduced tryptophan in their diets and saw several negative effects on memory and cognition. In patients with depression, it worsened their moods.

As he saw it, the next logical question to ask was: If a decrease in tryptophan levels worsens those symptoms, can an increase have the opposite effect?

He also conducts research on people with minimal cognition deficiency, or what he calls a very mild form of dementia. That is, people who, for example, have trouble finding their keys in the morning.

In addition to cognitive improvement, he and his team monitor changes in metabolism levels as a possible cause for memory loss.

Researchers had been attempting for decades to conduct similar experiments, until the discovery of a toxic byproduct in tryptophan supplements halted those efforts. Now, patients can ingest the amino acid via natural proteins.

“This research has been around for nearly 30 or 40 years. That’s not new,” Dr. Deutz explains, “What makes it new is finally bringing it to a translational/clinical level and having a practical application. We now have more tools to measure metabolism and safer ways to digest large amounts of tryptophan.”

To participate in this active study, visit CTRAL’s website at:


The Center for Translational Research in Aging and Longevity is engaged in ongoing translational research on nutrition, exercise, and metabolism in relation to aging and the common diseases of our aging population. These diseases include, cancer, heart failure, Chronic Obstructive Pulmonary Disease (COPD), obesity, cystic fibrosis (CF) and other chronic diseases of the older adult. The group seeks to translate knowledge from basic and applied sciences to care and clinical practice for older adults.

Media Contacts: Dominique Benjamin, Communications Specialist,

Dr. Nicolaas Deutz, Professor of Health and Kinesiology,