Aging
Conditions
Brief summary
The purpose of this study is to see whether people who have restricted the number of calories they eat for a long period of time, compared to normal-eating and obese people, have markers of cellular aging that look younger.
Interventions
None listed
Sponsors
Robert Wood Johnson Foundation
University of California, San Francisco
Study design
Observational model
COHORT
Time perspective
CROSS_SECTIONAL
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
Yes
Inclusion criteria
* Calorie restricting group: Self-reported caloric restriction for at least two years * Calorie restriction group: BMI below 23 * Normal eating control: Normal eating (no history of caloric restriction) for two years * Normal eating control: BMI below 30 * Obese comparison group: BMI above 30 * Obese comparison group: Normal eating (no history of caloric restriction) for two years
Exclusion criteria
* Regular smoker for the past six months
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Telomere Length | One day | This study is not a clinical trial, but the UCSF Committee on Human Research requires registration with clinicaltrials.gov. It is a ONE TIME POINT study, where we get a simple blood draw from people from three groups - calorie restricting, normal eating, and obese. Therefore, there IS NO FOLLOW UP/time frame. The outcome measure is assessed on the day of the study. Telomere length is a marker of cellular aging and is used to understand how the cells are aging. We will investigate whether long-term caloric restriction is associated cross-sectionally with longer telomere length (less aging). |
Countries
United States
Participant flow
Recruitment details
Calorie Restriction (CR) participants were recruited from the CR Society International, followers of the CR Way, and by referral from participants.
Pre-assignment details
Inclusion criteria and indicators for CR were reporting calorie restriction without malnutrition for a minimum of two years, BMI \< 24.99, and fasting glucose \<80 mg/dL.
Participants by arm
| Arm | Count |
|---|---|
| Calorie Restricting Group Inclusion criteria for the CR group were reporting calorie restriction without malnutrition for a minimum of two years and BMI \< 24.99. Whenever possible, the President of the CR Way Longevity Center and Vice President for Research of the CR Society International or the Chairman of the Board of The CR Society International and Treasurer and Vice President of the CR Way Longevity Center confirmed each participant's self-reported duration of and adherence to calorie restriction. Calorie restriction was also verified via four weekly random fasting glucose tests (\<80 mg/dL) with Bayer glucometers. Nursing staff verified BMI on-site. | 30 |
| Normal-eating Controls We recruited the comparison groups to match the CR group in age, race/ethnicity, gender, and educational attainment. Additionally, we recruited siblings of CR participants to attempt to control for genetic and environmental factors. All participants were non-smokers, and all were not pregnant. | 16 |
| Obese Comparison Group We recruited the comparison groups to match the CR group in age, race/ethnicity, gender, and educational attainment. Additionally, we recruited siblings of CR participants to attempt to control for genetic and environmental factors. All participants were non-smokers, and all were not pregnant. | 25 |
| Total | 71 |
Baseline characteristics
| Characteristic | Normal-eating Controls | Obese Comparison Group | Calorie Restricting Group | Total |
|---|---|---|---|---|
| Age, Continuous | 49.33 years STANDARD_DEVIATION 12.49 | 58.84 years STANDARD_DEVIATION 13.98 | 54.64 years STANDARD_DEVIATION 15.38 | 55.01 years STANDARD_DEVIATION 14.53 |
| Body Mass Index | 23.27 kg/m^2 STANDARD_DEVIATION 90.21 | 29.03 kg/m^2 STANDARD_DEVIATION 3.38 | 19.07 kg/m^2 STANDARD_DEVIATION 1.84 | 23.52 kg/m^2 STANDARD_DEVIATION 5.07 |
| Cytomegalovirus seropositive | 7 Participants | 13 Participants | 13 Participants | 33 Participants |
| Highest Degree Bachelor's | 6 Participants | 2 Participants | 5 Participants | 13 Participants |
| Highest Degree Doctoral | 2 Participants | 11 Participants | 14 Participants | 27 Participants |
| Highest Degree High School | 0 Participants | 1 Participants | 2 Participants | 3 Participants |
| Highest Degree Master's | 5 Participants | 2 Participants | 6 Participants | 13 Participants |
| Highest Degree Some college | 1 Participants | 3 Participants | 2 Participants | 6 Participants |
| Race/Ethnicity, Customized Race Asian | 2 Participants | 1 Participants | 3 Participants | 6 Participants |
| Race/Ethnicity, Customized Race White | 13 Participants | 24 Participants | 26 Participants | 63 Participants |
| Region of Enrollment Japan | 0 Participants | 0 Participants | 1 Participants | 1 Participants |
| Region of Enrollment United Kingdom | 0 Participants | 0 Participants | 1 Participants | 1 Participants |
| Region of Enrollment United States | 16 Participants | 25 Participants | 28 Participants | 69 Participants |
| Sex: Female, Male Female | 5 Participants | 3 Participants | 7 Participants | 15 Participants |
| Sex: Female, Male Male | 10 Participants | 22 Participants | 22 Participants | 54 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk | EG002 affected / at risk |
|---|---|---|---|
| deaths Total, all-cause mortality | 0 / 30 | 0 / 16 | 0 / 25 |
| other Total, other adverse events | 0 / 30 | 0 / 16 | 0 / 25 |
| serious Total, serious adverse events | 0 / 30 | 0 / 16 | 0 / 25 |
Outcome results
Primary
Telomere Length
This study is not a clinical trial, but the UCSF Committee on Human Research requires registration with clinicaltrials.gov. It is a ONE TIME POINT study, where we get a simple blood draw from people from three groups - calorie restricting, normal eating, and obese. Therefore, there IS NO FOLLOW UP/time frame. The outcome measure is assessed on the day of the study. Telomere length is a marker of cellular aging and is used to understand how the cells are aging. We will investigate whether long-term caloric restriction is associated cross-sectionally with longer telomere length (less aging).
Time frame: One day
| Arm | Measure | Group | Value (MEAN) | Dispersion |
|---|---|---|---|---|
| Calorie Restricting Group | Telomere Length | Telomere T/S ratio - peripheral blood mononuclear | 0.96 ratio | Standard Deviation 0.18 |
| Calorie Restricting Group | Telomere Length | Telomere T/S ratio - granulocyte | 1.22 ratio | Standard Deviation 0.21 |
| Normal-eating Controls | Telomere Length | Telomere T/S ratio - peripheral blood mononuclear | 1.06 ratio | Standard Deviation 0.15 |
| Normal-eating Controls | Telomere Length | Telomere T/S ratio - granulocyte | 1.20 ratio | Standard Deviation 0.23 |
| Obese Comparison Group | Telomere Length | Telomere T/S ratio - peripheral blood mononuclear | 1.06 ratio | Standard Deviation 0.23 |
| Obese Comparison Group | Telomere Length | Telomere T/S ratio - granulocyte | 1.14 ratio | Standard Deviation 0.22 |