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Completed

NCT Number: NCT07731633

Acute Metabolic Response Versus Long-term Adaptation to a Vegan Diet

At baseline, venous blood samples were collected from all eligible participants. The following biochemical parameters were analysed: serum electrolytes (mineral profile), fasting glucose, creatinine, urea nitrogen, total proteins, albumin, bilirubin, liver enzymes, C-reactive protein (CRP), total cholesterol, triacylglycerols (TAG), serum iron, active vitamin D, vitamin B12, complete blood count.

At baseline, all participants also underwent standardized anthropometric measurements, including height (cm), body weight (kg) and BMI was calculated accordingly. Body composition was assessed using bioelectrical impedance analysis with the InBody Tanita MC-780MA device. The following parameters were recorded: total body fat (kg, %), visceral fat (kg, %), skeletal muscle mass (kg, %), total muscle mass (kg, %), total body water (kg, %), sarcopenic index (kg/m²), phase angle.

To assess health-related quality of life and symptom burden, all participants completed validated questionnaires: World Health Organization Quality of Life - Brief Version (WHOQOL-BREF), Patient Assessment of Gastrointestinal Disorders - Symptom Severity Index (PAGI-SYM), Patient-Reported Outcomes Measurement Information System Global Health-10 (PROMIS-10), Patient Assessment of Upper Gastrointestinal Disorders - Quality of Life (PAGI-QoL) and Patient Health Questionnaire-15 (PHQ-15).

After the one-month intervention, participants in the VEG group repeated laboratory testing, anthropometric assessment, body composition analysis, and questionnaire evaluation. The same follow-up assessments were performed in the WD group for comparative purposes. Long-term vegans (VEG-P) did not undergo repeated measurements.

Dietary Monitoring and Adherence At study enrolment, all participants were offered a dietary consultation to improve adherence to the assigned dietary regimen. Participants were also instructed to maintain a food diary throughout the study period, which was periodically reviewed via telephone or email consultation.

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Key information

Conditions

Vegan Diet Body Composition Cardiometabolic Health Quality of Life (QOL)

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

University Hospital Martin

Martin, Žilina Region, 03601, Slovakia

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Age ≥ 18 years
  • Healthy individuals without chronic disease
  • BMI between 18 and 30 kg/m²
  • Provision of written informed consent
  • For the VEG-P group: exclusive adherence to a plant-based diet for at least 2 years
  • For the WD group: regular consumption of animal products for at least 2 years
  • For the intervention group (VEG): willingness to adhere to complete exclusion of animal products for the duration of the study

Exclusion criteria

  • Active infection
  • Eating disorder
  • Severe or unstable metabolic disease (e.g., diabetes mellitus)
  • Endocrine disorders
  • BMI < 18 or > 30 kg/m²
  • Age < 18 years
  • Current or past malignancy
  • Systemic corticosteroid therapy
  • Hormone replacement therapy
  • Pregnancy
  • Inability to complete follow-up assessments
  • Excessive alcohol consumption

Treatment and study plan

Vegan diet

Dietary Supplement

omnivores transmitted to vegan diet

Primary outcomes

  1. The difference in body weight (kg), between healthy vegans (more than 2 years) and omnivores.

    Time frame: Baseline

    To comprehensively compare body weight among individuals following different dietary patterns (long-term vegans and omnivores).

  2. The difference in body weight (kg) between omnivores and intervention group (omnivores transitioned to vegan diet).

    Time frame: From baseline to the end of intervention at 4 weeks

    To comprehensively compare body weight among individuals following different dietary patterns (long-term omnivores and intervention group).

  3. The difference in lipid profile (total cholesterol, triglycerides), between healthy vegans (more than 2 years) and omnivores.

    Time frame: Baseline

    At baseline, venous blood samples were collected from all eligible participants to analyse lipid profile: total cholesterol (mmol/l), triaglycerides (mmol/l).

  4. The difference in C-reactive protein (CRP), between healthy vegans (more than 2 years) and omnivores.

    Time frame: Baseline

    At baseline, venous blood samples were collected from all eligible participants to analyse CRP (mg/l).

  5. The difference in lipid profile (total cholesterol, triglycerides) between omnivores and intervention group (omnivores transitioned to vegan diet).

    Time frame: From baseline to the end of intervention at 4 weeks

    To comprehensively compare lipid profile parameters among individuals following different dietary patterns (long-term omnivores and intervention group). Venous blood samples were analyzed to measure total cholesterol (mmol/l) and triglycerides (mmol/l).

  6. The difference in C-reactive protein (CRP) between omnivores and intervention group (omnivores transitioned to vegan diet).

    Time frame: From baseline to the end of intervention at 4 weeks.

    To comprehensively compare CRP parameters among individuals following different dietary patterns (long-term omnivores and intervention group). Venous blood samples were analyzed to measure CRP (mg/l).

Secondary outcomes

  1. World Health Organization Quality of Life - Brief Version (WHOQOL-BREF)

    Time frame: From baseline to the end of intervention at 4 weeks

    To evaluate a difference in health-related quality of life using World Health Organization Quality of Life - Brief Version (WHOQOL-BREF), among individuals following different dietary patterns (long-term omnivores and intervention group - omnivores trasmitted to vegan diet).

  2. Patient Assessment of Gastrointestinal Disorders - Symptom Severity Index (PAGI-SYM).

    Time frame: From baseline to the end of intervention at 4 weeks.

    To evaluate a difference in health-related quality of life using Patient Assessment of Gastrointestinal Disorders - Symptom Severity Index (PAGI-SYM), among individuals following different dietary patterns (long-term omnivores and intervention group - omnivores trasmitted to vegan diet).

  3. Patient-Reported Outcomes Measurement Information System Global Health-10 (PROMIS-10).

    Time frame: From baseline to the end of intervention at 4 weeks.

    To evaluate a difference in health-related quality of life using Patient-Reported Outcomes Measurement Information System Global Health-10 (PROMIS-10), among individuals following different dietary patterns (long-term omnivores and intervention group - omnivores trasmitted to vegan diet).

  4. Patient Assessment of Upper Gastrointestinal Disorders - Quality of Life (PAGI-QoL).

    Time frame: From baseline to the end of intervention at 4 weeks.

    To evaluate a difference in health-related quality of life using Patient Assessment of Upper Gastrointestinal Disorders - Quality of Life (PAGI-QoL), among individuals following different dietary patterns (long-term omnivores and intervention group - omnivores trasmitted to vegan diet).

  5. Patient Health Questionnaire-15 (PHQ-15).

    Time frame: From baseline to the end of intervention at 4 weeks.

    To evaluate a difference in health-related quality of life using Patient Health Questionnaire-15 (PHQ-15), among individuals following different dietary patterns (long-term omnivores and intervention group - omnivores trasmitted to vegan diet).

Sponsors and collaborators

Lead sponsor

University Hospital, Martin

Other

Registry information

Official study title

Acute Metabolic Response Versus Long-term Adaptation to a Vegan Diet: a Prospective Study of Metabolic Health, Body Composition and Quality of Life

Acronym: VITAL

Important dates

Study start
2023
Primary completion
2024
Study completion
2024
First posted
Jul 28, 2026
Registry last updated
Jul 28, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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