How do vegetarian and vegan diets, compared to omnivore diets, impact risk factors for chronic degenerative disease (cardiovascular and cancer) incidence and disease-related mortality, and all-cause mortality?
There are overall trends of decreased risk factors for chronic degenerative diseases in vegetarians and vegans compared to omnivores. Although most studies included were weak in design, higher quality studies indicate some difference in disease incidence and mortality.
- 108 of 10516 studies qualified for analysis
- Selected 110 cross-sectional (not strong evidence) and 14 prospective cohort studies
- Study quality ranked on a 9-point scale; scores of 4+ included
- Vegetarian diets omit any animal flesh; vegan diets omit any animal-derived products
- Seventh-day Adventists were subjects in many vegetarian studies
- Measures: disease risk factors (BMI, total cholesterol, LDL, HDL, triglycerides, blood glucose), risk of all-cause mortality, and incidence and mortality-risk from cardiovascular disease and cancer.
Compared to omnivores, vegetarians and vegans had lower average differences in:
BMI:1.49 points1.72 points
Total cholesterol28.16 mg/dL31.02 mg/dL
LDL cholesterol21.27 mg/dL22.87 mg/dL
HDL cholesterol2.72 mg/dLnot significant
Triglycerides11.39 mg/dLnot significant
Blood Glucose5.08 ml/dL6.38 ml/dL
In Longitudinal cohort studies:
- Vegetarians had 25% reduced risk of incidence and/or mortality from ischemic heart disease.
- Vegetarians and vegans had an 8% and 15% reduced risk of incidence and/or mortality from cancer.
- Because Seventh-day Adventists are included in so many studies, other healthy lifestyle factors may be more prevalent than in the general population.
- There is no consistent definition of an “omnivore diet” – and the diets vary in quality.
- The studies don’t include information on how long the subjects have been vegetarian/vegan and adherence to the diet.