The health impact of plant-based foods

The Global Burden of Disease (GBD) Study collected data from 195 countries and territories, and subnational data from 16 countries.

Its aim was to model health risk and outcome associations.

The results indicated that leading risk factors for non-communicable diseases (NCDs) globally are:

  • low intake of fruits, vegetables, legumes, whole grains, nuts and seeds, milk, seafood n-3 fatty acids, n-6 polyunsaturated fatty acids (PUFA), calcium and fibre;
  • high intake of red meat, processed meat, sugar-sweetened beverages, trans fatty acids, and sodium.
  • Overall, studies assessing the relationship between food and health have consistently reported associations between low intakes of plant-based foods, as well as high intakes of animal products and UPFs (see Topic 2), and poor health outcomes.

These findings point to plant- versus animal-based diets and degree of food processing (Topic 2) as priority characteristics for analysing dietary patterns in the context of sustainability considerations. 

The quality of the plant-based diet is also an important consideration.

  • Those who adhere to a healthy plant-based diet are reported to have a lower Body Mass Index, waist circumference, and visceral fat than subjects following ‘unhealthy’ plant-based diets.
  • The implied shifts toward plant foods and away from animal sources (apart from fish and seafood) and for changes in food production systems are directly related to the sustainability agenda

1. Gut microbiome

The consumption of a plant-based diet is rich in fiber and phytochemicals like polyphenolics

  • Have a substantial impact on the composition and function of the gut microbiome, which in turn influences overall health.
  • Contribute to a diverse gut microbiota producing metabolites with anti-inflammatory functions that may help manage disease processes and even provide disease-preventing benefits.

Picture from Harvard Health Publishing. Diet, disease, and the microbiome By Sue-Ellen Anderson-Haynes.

2. Cardiovascular Diseases (CVD)

  • Vegetarian diets have been associated with a 22% reduced incidence of coronary heart disease and a 28% reduced mortality incidence of CVDs. 
  • Trials including vegan and vegetarian diets have shown improvements in several cardiometabolic risk markers (including body weight, blood lipids, and cardiometabolic risk profiles). 

The Adventist Health Study-2 (AHS-2) showed that:

  • Vegetarians had a 13% and 19% lower risk of CVD and ischemic heart disease mortality, respectively, compared with non-vegetarians (a difference was reported despite the fact that non-vegetarians in the study consumed less meat than the general population).
  • Blood pressure levels in vegans and vegetarians were also lower than those consuming meat.
  • A reduced prevalence of metabolic syndrome and type 2 diabetes, which are major risk factors for CVD, and stroke was observed in vegan and vegetarian participants.

3. Type 2 Diabetes

  • Observational studies in a variety of populations showed that compared to non-vegetarians, those following a plant-based diet have a significantly lower risk of Type 2 Diabetes (T2D). 
  • Possible explanations for the benefits of plant-based diets for diabetes prevention and management: 
  • In comparison to most western diets, vegetarian and vegan diets are generally higher in dietary fiber and are likely to include more whole grains, legumes and nuts, all of which have been associated with a reduced risk of T2D.
  • Evidence for an inverse association between higher intakes of green leafy vegetables and fruits and the T2D risk.
  • Overweight and obesity are significant contributors to insulin resistance and T2D risk, and weight loss is a key component of the management of T2D.
  • None-meat eaters generally have healthier lifestyles than meat eaters 3 and those following a plant-based diet are less likely to have excess body weight.

4. Cancer

Each of the plant-based food-groups possess chemo-protective properties and are rich in health-promoting phytochemicals. 4

According to published scientific literature: 

  • an increased nut consumption was associated with both a decreased risk of all cancers combined and decreased cancer mortality.
  • an increased intake of fruits and vegetables and of whole grains was shown to decrease the risk of total cancer incidence and total cancer mortality, respectively.
  • a higher intake of legumes (beans and lentils) was associated with a reduction in the risk of gastro-intestinal cancers and all cancer sites combined.

Vegans, vegetarians and pescatarians have been found to have a lower risk for all cancers compared to non-vegetarians. 

World Cancer Research Fund:

Diets reducing the risk of cancer contain no more than modest amounts of red meat and little or no processed meat.