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Lipid MetabolismTwiNSNCT05297825

Twins Nutrition Study (TwiNS): Vegan vs. Omnivore

A study testing Vegan diet and Omnivore diet in people with Lipid Metabolism and Glucose Intolerance, run by Stanford University at 1 site in United States.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record
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Trial summary

This study is designed to investigate the health impact of a vegan diet compared to a usual, omnivorous diet. The investigators plan to study these diets in twins, where one twin follows a vegan diet and the other twin follows an omnivorous diet, thus the investigators control for genetic differences that might impact… Read more about this study

Who is it for?
Ages 18 years and olderHealthy volunteers can take part
What is being tested?
Vegan diet and Omnivore diet
Could I receive a placebo?
No, everyone receives an active treatment
How many people
44 participants
Where
1 siteUnited States
Study dates
17 Mar 2022to 20 Jul 2022
Phase
Interventional
Are there results?
None posted in the registry

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 years and older
  • All sexes
  • Healthy volunteers accepted
  • Adult, Older adult

Who may be able to join

  • Age 18+
  • 1/2 of a pair of twins that will both be participating
  • Willing to consume a plant-based diet (vegetables, fruit, whole grains, legumes, etc.)
  • Willing to consume meat/eggs (beef, pork/sausage, chicken, eggs) >= 1 time a day
  • Willing to consume dairy (milk, yogurt, cheese) >= 1 time a day

Who cannot join

  • Weight < 110 lb
  • BMI >= 40
  • LDL-C > 190 mg/dL
  • Systolic Blood Pressure > 160 mmHg OR Diastolic blood pressure > 90 mmHg
  • Pregnant, lactating or planning to become pregnant during the course of the study.
  • Use of any of the following drugs/supplements within the last 2 months:
Show all 18Show fewer
  • systemic antibiotics, antifungals, antivirals or antiparasitics (intravenous, intramuscular, or oral);
  • corticosteroids (intravenous, intramuscular, oral, nasal or inhaled);
  • cytokines;
  • methotrexate or immunosuppressive cytotoxic agents.
  • Chronic, clinically significant, or unstable (unresolved, requiring on-going changes to medical management or medication) pulmonary, cardiovascular, gastrointestinal, hepatic or renal functional abnormality, as determined by medical history, Type 1 diabetes, dialysis
  • History of active cancer in the past 3 years except for squamous or basal cell carcinomas of the skin that have been medically managed by local excision
  • Unstable dietary history as defined by major changes in diet during the previous month, where the subject has eliminated or significantly increased a major food group in the diet.
  • Recent history of chronic excessive alcohol consumption defined as more than five 1.5-ounce servings of 80 proof distilled spirits, five 12-ounce servings of beer or five 5-ounce servings of wine per day; or > 14 drinks/week.
  • Any confirmed or suspected condition/state of immunosuppression or immunodeficiency (primary or acquired) including HIV infection, multiple sclerosis and Graves' disease.
  • Surgery of the GI tract, with the exception of cholecystectomy and appendectomy, in the past five years. Any major bowel resection at any time.
  • Regular/frequent use of smoking or chewing tobacco, e-cigarettes, cigars or other nicotine-containing products
  • Regular use of prescription opiate pain medication

Trial locations and contacts

1 site in 1 country.

United States1 site

  • Stanford University

    Stanford, California, 94305

Other trials in United States

About this study

This study is designed to investigate the health impact of a vegan diet compared to a usual, omnivorous diet. The investigators plan to study these diets in twins, where one twin follows a vegan diet and the other twin follows an omnivorous diet, thus the investigators control for genetic differences that might impact the effect of the diet.

Read the detailed description

During this study, the investigators will evaluate the nutrient intake in both the vegan and the omnivorous diet. The investigators will also measure physiologic markers of health such as lipid levels, HbA1C, heart rate, and weight, and they will also look at the effect of the diets on the microbiota. In addition to measuring the effect of the diet, the investigators will monitor adherence to the diet, and survey participants on the ease/difficulty in following a vegan diet as well as their energy levels and sense of wellbeing. Thus, this study will help us better understand the health impact and feasibility of following a vegan diet. These results will be of much interest to the general public and the health care professionals.

Being tested
Vegan diet, Omnivore diet
Keywords
Lipids, Glucose, Body weight, Microbiome, Inflammation, Immune function
Medical subject headings
Glucose Intolerance, Body Weight Changes, Inflammation, Body Weight

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • Vegan dietBehavioural

    Healthy vegan diet.

  • Omnivore dietBehavioural

    Healthy omnivore diet.

Study groups in NCT05297825
Study groupRoleWhat they receive
VeganExperimentalParticipants will be asked to consume a healthy vegan diet.
Receives: Behavioral: Vegan diet
OmnivoreExperimentalParticipants will be asked to consume a healthy omnivore diet.
Receives: Behavioral: Omnivore diet

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Difference in LDL cholesterol

    Difference in the 8-week change-from-baseline in LDL cholesterol between the vegan vs. omnivore diet groups

    Measured: Baseline and 8 weeks

Secondary outcomes (3)

  1. Difference in triglycerides

    Difference in the 8-week change-from-baseline in triglycerides between the vegan vs. omnivore diet groups

    Measured: Baseline and 8 weeks

  2. Change in inflammatory markers

    Difference in the 8-week change-from-baseline in inflammatory markers detected in blood samples between the vegan vs. omnivore diet groups.

    Measured: Baseline and 8 weeks

  3. Change in alpha diversity

    Change from baseline in alpha diversity at 8 weeks in the vegan and omnivore diet groups. We will be using the number of observed sequence variants ("species") determined by standard 16S rRNA amplicon sequencing (V3-V5 region followed by DADA2 to define error-corrected sequence variants) as our primary metric of alpha diversity. We will also determine whether there is a change in observed sequence variants between the two groups. Higher alpha diversity is better. The units are the number of sequence variants.

    Measured: Baseline and 8 weeks

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted28 Mar 2022
  2. Study start17 Mar 2022
  3. Primary completion20 Jul 2022
  4. Study completion20 Jul 2022

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase N/A
Primary purpose
Prevention
Allocation
Randomised
Intervention model
Parallel groups
Masking
None (open label)
Enrolment
44 participants (actual)
IDs, dates and publications
ClinicalTrials.gov ID
NCT05297825
Sponsor's protocol ID
63995
Acronym
TwiNS
Status last verified
Dec 2023
First submitted
17 Mar 2022
Last updated
12 Jan 2024
Results posted
No
Data monitoring committee
Yes
FDA-regulated drug
No
FDA-regulated device
No
Individual data sharing
No

Publications

  • Landry MJ, Ward CP, Cunanan KM, Durand LR, Perelman D, Robinson JL, Hennings T, Koh L, Dant C, Zeitlin A, Ebel ER, Sonnenburg ED, Sonnenburg JL, Gardner CD. Cardiometabolic Effects of Omnivorous vs Vegan Diets in Identical Twins: A Randomized Clinical Trial. JAMA Netw Open. 2023 Nov 1;6(11):e2344457. doi: 10.1001/jamanetworkopen.2023.44457.

    PubMed 38032644

  • Zeitlin AB, Ward CP, Minerva Cooper AO, Landry MJ, Krenek AM, Durand LR, Cunanan KM, Robinson JL, Dant CC, Gardner CD. Diet Quality and Comparison of Plant-Based Versus Omnivore Diets in Identical Twins: A Secondary Analysis of the Twins Nutrition Study (TwiNS). Curr Dev Nutr. 2025 Sep 4;9(10):107549. doi: 10.1016/j.cdnut.2025.107549. eCollection 2025 Oct.

    PubMed 41081008

  • Dwaraka VB, Aronica L, Carreras-Gallo N, Robinson JL, Hennings T, Carter MM, Corley MJ, Lin A, Turner L, Smith R, Mendez TL, Went H, Ebel ER, Sonnenburg ED, Sonnenburg JL, Gardner CD. Unveiling the epigenetic impact of vegan vs. omnivorous diets on aging: insights from the Twins Nutrition Study (TwiNS). BMC Med. 2024 Jul 29;22(1):301. doi: 10.1186/s12916-024-03513-w.

    PubMed 39069614

Questions about this trial

What is this clinical trial studying?

A study testing Vegan diet and Omnivore diet in people with Lipid Metabolism and Glucose Intolerance, run by Stanford University at 1 site in United States.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 5 inclusion and 18 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 12 Jan 2024. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

Are results available for this study?

The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Difference in LDL cholesterol (time frame: Baseline and 8 weeks). It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT05297825, which also lists 3 linked publications.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 12 Jan 2024.

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