Effect of a Vegan Diet Versus a Mediterranean Diet. Assessing Health Outcomes (OMNIVEG)

Effect of a Vegan Diet Versus a Mediterrean Diet on Performance, Cardiorespiratory Fitness, Metabolic Health, Immune Status, and Environmental Impact in Healthy Adults

This study aimed to evaluate the effect of a vegan diet (supplemented with vitamin B12) and an mediterranean diet on performance, cardiorespiratory fitness, metabolic health, immune status, and environmental impact in healthy adults.

Study Overview

• Status: Completed
• Conditions: Cardiometabolic Syndrome
• Intervention / Treatment: Behavioral: Vegan diet; Behavioral: Mediterranean diet

Detailed Description

OMNIVEG is a controlled crossover trial. Initially, registered dietitians conducted an assessment of participants' lifestyles in a preliminary session. Qualified nutritionists then developed personalized diets for each participant in accordance with the recommendations of the International Society of Sports Nutrition (ISSN). These diets followed specific guidelines, including a daily intake of 3-5 g of carbohydrates per kilogram of body weight, 1.4-2.0 g of protein per kilogram of body weight, and 0.5-1.5 g of fat per kilogram of body weight.

Both the mediterranean diet and vegan diets prescribed to the participants were isocaloric, with similar distributions of macronutrients. The primary difference between the two interventions was the source of food: the vegan diet exclusively comprised plant-based foods, while the omnivorous diet included foods of both animal and plant sources. In the case of the omnivorous diet, 60% of the total protein intake was derived from animal sources (mainly from fish, white meat, low-fat dairy and eggs).

As part of the vegan diet, participants were instructed to take 1000 µg of cyanocobalamin (a form of vitamin B12) twice a week from Harrison Sport Nutrition, Granada, Spain. This supplementation aimed to ensure adequate vitamin B12 intake, which is essential for individuals following a vegan diet.

Throughout the study period, participants were advised to maintain their initial physical exercise frequency and volume to maintain consistency and avoid confounding variables. To ensure standardized measurements, all tests were conducted in the same laboratory, employing identical testing devices, and supervised by the same group of researchers. This approach aimed to minimize experimental variability and improve the reliability of the study's results.

• Study Type: Interventional
• Enrollment (Actual): 14
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Spain
  • Madrid, Spain, 28223
    • Francisco de Vitoria University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Men.
• Aged between 18-40 years.
• Physically active according to the recommendations of the World Health Organization (WHO).
• Body Mass Index (BMI) between 18.5-24.9 kg/m2.
• No tobacco use.
• No or low alcohol consumption and no orthopedic limitations that would interfere with the performance of the study tests.

Exclusion Criteria:

• Chronic diseases that impair athletic performance (cardiovascular, metabolic, gastrointestinal, respiratory) within the last six months.
• Musculoskeletal disease within the last six months.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Non-Randomized
• Interventional Model: Crossover Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Vegan diet; Vegan diet all foods included were of plant sources. During the vegan diet, the participants took 1000 µg of cyanocobalamin twice a week (Harrison Sport Nutrition, Granada, Spain)	Behavioral: Vegan diet; Normocaloric diet based solely on foods of plant sources.
Active Comparator: Mediterranean diet; In the case of the mediterranean diet, foods of animal sources were also included (animal protein accounted for 60% of total protein intake). In this diet there was a predominance of plant foods; moderate to low consumption of fish, white meat, low-fat dairy and eggs; and very low consumption of red and processed meats, butter, full-fat dairy and sweets.	Behavioral: Mediterranean diet; Diet with a predominance of plant foods fruits, vegetables, whole grains, nuts and legumes); moderate to low consumption of fish, white meat, low-fat dairy and eggs; and very low consumption of red and processed meats, butter, full-fat dairy and sweets.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Cardiorespiratory fitness	Cardiorespiratory fitness was measured using Maximal oxygen uptake (VO2max).	4 weeks
Metabolic health	Metabolic health was measured using serum total cholesterol (TC), cholesterol-LDL (LDL-c) and colesterol-HDL (HDL-c)	4 weeks
Performance	Performance was measured using FATmax (g/min).	4 weeks
Performance	Performance was measured using countermovement (CMJ) (W) and squat jump (SJ).	4 weeks
Performance	Performance was measured using squat jump (SJ) (W)	4 weeks
Environmental impact assessment	Environmental impact was measured using Global-warming potential-100	4 weeks
Inmune status	Inmune status was measured using lymphocyte levels (109/L )	4 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Performance	Performance was measured using handgrip	4 weeks
Metabolic health	Metabolic health was measured using systolic blood pressure (SBP) and diastolic blood pressure (DBP).	4 weeks
Inmune status	Inmune status was measured using monocyte, eosinophils and neutrophils levels (10^9/L)	4 weeks
Environmental impact assessment	Environmental impact was measured using blue water footprint and land use.	4 weeks

Collaborators and Investigators

• Sponsor: Universidad Francisco de Vitoria
• Investigators: Principal Investigator: Miguel López Moreno, Phd, Universidad Francisco de Vitoria

Study record dates

Study Major Dates

• Study Start (Actual): June 19, 2023
• Primary Completion (Actual): August 28, 2023
• Study Completion (Actual): September 4, 2023

Study Registration Dates

• First Submitted: July 28, 2023
• First Submitted That Met QC Criteria: August 18, 2023
• First Posted (Actual): August 24, 2023

Study Record Updates

• Last Update Posted (Actual): November 28, 2023
• Last Update Submitted That Met QC Criteria: November 27, 2023
• Last Verified: August 1, 2023

More Information

Terms related to this study

• Keywords: Performance; Mediterranean diet; Cardiorespiratory Fitness; Plant-Based Diet; Metabolic Health; Vegan diet; Environmental Impact
• Additional Relevant MeSH Terms: Glucose Metabolism Disorders; Metabolic Diseases; Insulin Resistance; Hyperinsulinism; Metabolic Syndrome
• Other Study ID Numbers: 20/2023

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No