Clinical trial NCT06283706: The Tryptophan Requirement in Healthy Adults
Official title: The Tryptophan Requirement in Healthy Adults Over 60 Years
Study type: INTERVENTIONAL
Overall status: RECRUITING
Phase: NA
Conditions: Healthy Aging
Keywords: elderly
healthy
tryptophan requirement
indicator amino acid oxidation
stable isotopes
Lead sponsor: The Hospital for Sick Children
Sponsor class: OTHER
Collaborators: name: Canadian Institutes of Health Research (CIHR)
First posted: 2024-02-28
Enrollment: 40
Sex: ALL
Minimum age (years): 60
Maximum age (years): 90
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Allocation: NA
Intervention model: SINGLE_GROUP
Primary purpose: BASIC_SCIENCE

Brief summary: The aging population is growing rapidly. For the first time ever, Canadian seniors outnumbered young adults in 2016. Aging is associated with many physical and metabolic deteriorations including the loss of muscle mass and strength, insulin resistance, increased inflammation and oxidative stress.

The muscles of our bodies are composed of proteins and proteins are made of small building blocks called amino acids. Our bodies have the ability to make some amino acids which are called the non-essential amino acids. However, there are certain amino acids that our body's need to make protein but can only be supplied from the foods that we consume. These are called essential amino acids. Tryptophan is one of the essential amino acids that the body needs. Tryptophan is required for protein synthesis and acts as a precursor for serotonin and nicotinic acid. Therefore, there may be a need for more threonine in the diet of older adults. However, the current requirement for threonine is based on studies conducted exclusively in young adults. Thus, the purpose of this study is to find out how much tryptophan older adults need.

Detailed description: Tryptophan is an essential amino acid and must be obtained from the diet. It is required for protein synthesis and acts as a precursor for serotonin and nicotinic acid. It is of particular importance in the diet of people who receive a large percentage of their calories from cereal grains such as maize, as it is limiting in tryptophan. Therefore, accurate knowledge of tryptophan requirement is important for dietary planning particularly for older adults. In 1998, our lab determined the tryptophan requirement in young women to be 4.01 mg/kg/day, with a safe intake at 5 mg/kg/day, using the Indicator Amino Acid Oxidation method. Since then, the investigators have determined the tryptophan requirement and safe level in healthy school-age children to be 4.7 and 6 mg/kg/day. The investigators have recently found the requirements of essential amino acids such as leucine and total sulfur amino acids in older adults and have found to be higher than young adults and a difference between the sexes. Thus, there is a need to determine the threonine requirement in older adults.

Eligibility criteria: Inclusion Criteria:

* Consent provided.
* Aged 60 to 90 years old.
* In good general health as evidenced by medical history, physical health and blood draw.
* Fasting blood glucose, hemoglobin A1c (HbA1c), urea, creatinine.
* Willingness to participate in the study.
* BMI \<30 kg/m2.

Exclusion Criteria:

* Presence of chronic disease and/or acute illness known to affect protein/amino acid metabolism (e.g. HIV, diabetes, taking medications known to affect protein/AA metabolism (e.g. steroids).
* Inability to tolerate the diet (i.e. allergy).
* Significant weight loss during the past month or consumption of weight reducing diets.
* Significant caffeine consumption (\>2 cups per day).
* Significant consumption of alcohol (\>1 drink per day i.e. 1 beer or ½ glass of wine).
* Unwilling to have blood drawn from a venous access or using a ventilated hood indirect calorimeter for the purposes of the study.

Primary outcomes:
measure: Determination of tryptophan requirement in adults >60 years of age.
timeFrame: up to 24 months
Secondary outcomes:
Other outcomes:
Locations:
city: Toronto
country: Canada
facility: Hospital for Sick Children
state: Ontario
Study officials:
affiliation: The Hospital for Sick Children
name: Glenda Courtney-Martin, PhD, RD
role: PRINCIPAL_INVESTIGATOR
References: