Cancer

Vegan Vs. Omnivore

American Journal of Clinical Nutrition (2013)
"Vegetarian dietary patterns and the risk of colorectal cancers" — This study found that vegetarians, including vegans, had a lower risk of colorectal cancer compared to omnivores.


JAMA Internal Medicine (2017)
"Vegetarian Dietary Patterns and Mortality in Adventist Health Study 2" — This large cohort study found that vegans had a 15% lower risk of overall cancer incidence compared to non-vegetarians.


Nutrition and Cancer (2019)
"Plant-based diets and cancer risk: A review of recent epidemiological evidence" — This review concluded that plant-based diets, including vegan diets, are associated with a reduced risk of several cancers compared to diets high in animal products.

Summary:
Evidence suggests vegans tend to have a lower risk of certain cancers compared to omnivores, particularly colorectal cancer, likely due to higher intake of fiber, antioxidants, and lower intake of processed and red meats.

cardiovascular Disease

Vegan Vs. Omnivore

Overall, evidence suggests that vegans and vegetarian diets are linked with better cardiovascular health outcomes compared to omnivorous diets, especially in coronary heart disease (CHD). However, findings vary—some outcomes like stroke risk show mixed results.

Supporting Evidence
1. Meta-Analyses & Observational Reviews
A comprehensive systematic umbrella review reports that vegetarian, including vegan, diets were associated with reduced risk of CVD incidence (relative risk ≈ 0.85) and CVD mortality (hazard ratio ≈ 0.92) compared to non-vegetarian diets. They also observed reductions in risk factors like blood pressure, LDL cholesterol, BMI, and C-reactive protein.
Reddit

An umbrella review found that vegetarians have significantly lower risk of ischemic heart disease (IHD; RR ≈ 0.71) and overall CVD (RR ≈ 0.85), while vegans also showed a reduced IHD risk (RR ≈ 0.82), though the stroke difference wasn’t significant.
PMC

2. Observational Cohort & Cross-Sectional Studies
A Polish cross-sectional study showed vegans had significantly lower serum cholesterol, LDL, triglycerides, fasting glucose, C-reactive protein, and no cases of overweight, obesity, impaired fasting glucose, or high blood pressure—unlike omnivores.
PubMed

PMC

In Brazil, a study using the Framingham risk score reported lower calculated cardiovascular risk for long-term vegetarians compared to matched omnivores; vegetarians had lower blood pressure, glucose, cholesterol, LDL, and triglycerides.
PubMed


3. Intervention Trials
A randomized clinical trial involving identical twins (JAMA Network Open, Nov 2023) found that over 8 weeks, the vegan twins had notably greater reductions in LDL cholesterol and fasting insulin, plus more weight loss, compared to their omnivorous twins.
Harvard Health

Summary
Overall trend: Vegan and vegetarian diets are generally associated with improved cardiovascular biomarkers and lower risk of ischemic heart disease.

Strength of evidence: Observational data is supportive but not uniformly conclusive; randomized controlled trials (like the twin study) offer stronger but still limited-duration evidence.

Variability in outcomes: Protective effects are strongest for coronary heart disease; evidence is mixed for stroke and overall CVD depending on the study.

Further Reading: Three Helpful Links
Umbrella review of plant-based diets – Reduced CVD incidence (RR ≈ 0.85) and mortality, plus improved risk factors
Reddit

Cross-sectional study (Poland) – Vegans show superior cholesterol, glucose, BP, and inflammation markers
PubMed
PMC

Identical-twin RCT (JAMA Network Open) – Vegan diet led to greater LDL & insulin reduction, more weight loss in just 8 weeks
Harvard Health
Health

In short, while not every study is in full agreement, the bulk of well-synthesized observational and some intervention data points toward cardiovascular benefits of vegan diets, particularly in reducing risk factors and coronary heart disease.

Diabetes

Vegan Vs. Omnivore

Multiple sources indicate that vegans (and vegetarians) generally have lower rates of type 2 diabetes compared to omnivores. Here are three informative links supporting this:

VeganHealth provides pooled data showing that, in the EPIC-Oxford cohort, vegans had about half the risk of diabetes diagnosis or death compared to meat-eaters (HR ~0.53); in the Adventist Health Study-2, vegans had a 60% lower risk of developing diabetes versus regular meat-eaters (HR ~0.38)
VeganHealth.org

A MDPI systematic review found that vegan diets are associated with lower prevalence or incidence of type 2 diabetes, and in people already diagnosed, such diets help reduce high glucose levels and improve glucose homeostasis
MDPI

An observational long-term cohort study summarized by the American Society for Nutrition reported that the prevalence of diabetes was about 49% lower among vegans and 46% lower among lacto-ovo vegetarians compared to non-vegetarians
Nutrition.org


Quick Summary
Diet Type    Relative Risk / Prevalence vs. Omnivores
Vegan (EPIC-Oxford)    ~47% less risk (HR ~0.53)
Vegan (AHS-2)    ~62% less risk (HR ~0.38)
Vegans overall    ~49% lower prevalence

These findings come from well-conducted observational cohorts and comprehensive reviews, suggesting a consistent association between vegan diets and significantly lower diabetes risk. However, remember that these diets are often part of broader lifestyle patterns, and causation isn't guaranteed. Clinical trials do show improvements in glycemic control among diabetics following vegan diets—a promising sign for both prevention and management.

Heart Attack

Vegan Vs. Omnivore

Vegans generally appear to have a lower risk of heart attacks compared to omnivores—but the magnitude and consistency of this benefit depend on the quality of the plant-based diet and other lifestyle factors. Here are three strong sources to support this finding:

Evidence Summary & Supporting Links
Stanford Twins Study (JAMA Network Open)
In a randomized trial of 22 pairs of identical twins (one following a vegan diet, the other an omnivorous diet) over eight weeks, the vegan twins showed significantly improved cardiovascular markers, including lower LDL cholesterol and insulin, along with modest weight loss—suggesting better heart-health potential.
Harvard Health

Medical News Today

Harvard Study on Plant-Based Protein Intake
A large cohort study following over 200,000 individuals for 30 years found that those consuming a higher proportion of plant-based protein relative to animal protein had a 19% lower risk of cardiovascular disease and a 27% lower risk of coronary artery disease.
Harvard Health

Umbrella Review of Vegetarian & Vegan Diets (American Journal of Preventive Cardiology)
A review covering 21 systematic reviews shows that vegetarian and vegan dietary patterns are linked to:

15% lower risk of developing cardiovascular disease,

Improved markers like lower blood pressure, LDL cholesterol, BMI, and inflammation.
publichealth.uci.edu

Eat Right Pro

Quick Takeaway
Overall, vegan or largely plant-based diets are associated with reduced heart attack and cardiovascular risk.

inflammation

Vegan Vs. Omnivore

Research indicates that vegans often exhibit lower levels of inflammation compared to omnivores. Here are three studies supporting this finding:

1.  Systematic Review and Meta-Analysis of Vegan and Vegetarian Diets
This comprehensive analysis found that plant-based diets, including vegan and vegetarian diets, are associated with reduced levels of inflammatory biomarkers such as C-reactive protein (CRP), interleukin-6 (IL-6), and soluble intercellular adhesion molecule-1 (sICAM-1). These reductions suggest a potential anti-inflammatory effect of plant-based diets.
Cambridge.org

2.  Associations of a Vegan Diet with Inflammatory Biomarkers
This study observed that individuals adhering to a vegan diet had lower concentrations of CRP and sICAM-1, markers commonly associated with inflammation. These findings support the hypothesis that vegan diets may help modulate inflammatory responses.
lipidworld.biomedcentral.com

3.  Plant-Based Diets and Lipid, Lipoprotein, and Inflammatory Biomarkers
This research highlighted that plant-based diets are generally associated with favorable lipid and lipoprotein profiles and reduced low-grade inflammation, characterized by decreased CRP concentrations. The study suggests that plant-based diets can positively influence inflammatory biomarkers.
nature.com

These studies collectively suggest that adopting a vegan diet may contribute to lower inflammation levels compared to omnivorous diets.
PMC

biomedcentral.com

Omnivore vs. Vegan
Mortality Rate

Many studies suggest that vegans tend to have a lower overall mortality rate compared to omnivores. This is often attributed to lower risks of chronic diseases such as cardiovascular disease, type 2 diabetes, and certain cancers among vegans.

Key Research Highlights:

Adventist Health Study-2 (AHS-2):
This large U.S.-based study of Seventh-day Adventists found that vegans had about a 15% lower risk of all-cause mortality compared to non-vegetarians (mostly omnivores). Vegans also showed lower rates of heart disease and cancer-related deaths.

EPIC-Oxford Study (UK):
This cohort study found that vegetarians and vegans had lower mortality rates from ischemic heart disease compared to meat-eaters. However, some results showed slightly higher mortality from other causes in vegans, but overall mortality was similar or slightly lower in vegans.
(Source: Appleby et al., Am J Clin Nutr, 2016)
    
Meta-Analyses:
Some meta-analyses combining multiple studies indicate a modest reduction (about 10-15%) in all-cause mortality for vegans versus omnivores, mainly due to reductions in cardiovascular disease deaths.
https://www.tandfonline.com/doi/full/10.1080/10408398.2016.1138447

Potential Confounders:
Lifestyle factors often associated with vegans (such as lower smoking rates, more physical activity, healthier BMI which may be due to Vegan diet) can partly explain the mortality differences, but even after adjustments, benefits often remain.

Obesity

Vegan Vs. Omnivore

Research consistently shows that vegans and those following more plant-based dietary patterns tend to have lower rates of obesity compared to omnivores.

Here are two reliable sources you can explore:

EPIC-Oxford study (International Journal of Obesity, 2003)
This large-scale study compared meat-eaters, fish-eaters, vegetarians, and vegans. It found that vegans had the lowest average BMI, significantly lower than meat-eaters, with differences only minimally influenced by lifestyle—diet composition (e.g. higher fiber, lower protein) was a key factor.
Nature

U.S. women’s cohort (American Journal of Clinical Nutrition, 2005)
In this observational study of over 55,000 women, the prevalence of overweight or obesity (BMI ≥ 25) was 40% among omnivores, but only 29% among vegans and semivegetarians. Vegans had a dramatically lower odds ratio of 0.35 (95% CI: 0.18–0.69) for overweight/obesity compared to omnivores.
PubMed


In summary:

Vegans generally have lower obesity rates and BMI levels compared to meat-eaters.

Studies like the EPIC-Oxford and the Swedish Mammography Cohort provide strong epidemiological evidence supporting this trend.

Parkinson's disease

Vegan Vs. Omnivore

Research indicates that vegans and those adhering to plant-based diets may have a lower risk of developing Parkinson's disease compared to omnivores. Here are three supporting studies:

1.  A large-scale study published in Movement Disorders found that individuals with higher adherence to a healthful plant-based diet had a 22% lower risk of Parkinson's disease. This protective effect was particularly notable among those consuming more vegetables, nuts, and tea. Conversely, diets rich in unhealthy plant-based foods were associated with a 38% increased risk.
Verywell Health

PubMed

Forks Over Knives

2.   An article from the Davis Phinney Foundation discusses a UK study revealing that individuals with the greatest adherence to a plant-based diet had a 19% decreased risk of Parkinson's disease. The article also highlights mechanisms such as increased expression of neuroprotective proteins and beneficial changes in the gut microbiome associated with plant-based diets.
pbdmedicine.org

3.  A study referenced by Mass General Brigham indicates that individuals with high intake of plant foods, including fruits, vegetables, beans, and whole grains, had a lower risk of developing Parkinson's disease. This aligns with findings from the Harvard T.H. Chan School of Public Health, which observed that adherence to a Mediterranean-style diet, rich in plant-based foods, was associated with a lower risk of Parkinson's.

Mass General Brigham

Davis Phinney Foundation



These studies suggest that plant-based diets, particularly those rich in whole, unprocessed foods, may offer protective benefits against Parkinson's disease.

Weight & BMI

Vegan Vs. Omnivore

Evidence shows that, on average, vegans tend to have lower body weight and BMI compared to omnivores. Here are three solid studies that support this:

1. Swedish Mammography Cohort: Lower Overweight Risk for Vegans
In this cross-sectional analysis of over 55,000 women, researchers found that:

40% of omnivores were overweight or obese,
29% of both semivegetarians and vegans were overweight or obese.

Vegans had a 65% lower odds of being overweight or obese compared to omnivores (OR = 0.35; 95% CI: 0.18–0.69).
PubMed

2. EPIC-Oxford Cohort: Vegans Have Lower BMI and Less Weight Gain Over Time
Within the EPIC-Oxford study:
Vegans had BMIs approximately 1–2 points lower than meat-eaters.

Over 5 years, vegans gained significantly less weight (≈ 300 g/year) compared to meat-eaters (≈ 400 g/year).
https://pmc.ncbi.nlm.nih.gov/articles/PMC7613518/?utm_source=chatgpt.com

3. Randomized Trials: Vegan Diets Lead to Greater Weight Loss
Several controlled trials demonstrate that vegan interventions result in notable weight reductions:

Plant-based – 16-week trial: Participants on a vegan diet lost an average of 6.5 kg compared to controls; also saw fat mass and insulin resistance reductions.
PubMed

Low-fat vegan – 16-week randomized trial (JAMA): Overweight adults lost 5.9 kg, along with reductions in fat stores and improved metabolism.
PubMed

JAMA Network      


Summary
Observational studies show lower BMI and lower overweight risk among vegans.

Longitudinal cohort data indicates less age-related weight gain in vegans.

Intervention trials confirm that vegan diets lead to meaningful weight loss and metabolic benefits.