In a narrative review published in Nutrients, researchers from Italy discussed the health and environmental benefits conferred by plant-based diets (PBDs) and the challenges associated with a potential shift to them.
Further, they address the factors associated with PBD affordability and acceptability and propose recommendations for policy makers to potentially update the current dietary guidelines.
Study: Exploring Benefits and Barriers of Plant-Based Diets: Health, Environmental Impact, Food Accessibility and Acceptability. Image Credit: Chay_Tee/Shutterstock.com
The world today faces a cluster of three pandemics: obesity, undernutrition, and climate change, that are known collectively as the “Global Syndemic.” Hunger continues to affect 150 million children globally, while obesity affects about two billion individuals.
The gradual transition from traditional diets to “Western diets” with higher levels of sodium, saturated fats, sugar, and meat is especially concerning, and shown to be associated with various health conditions (including obesity) as well as early all-cause mortality.
Human health is further threatened by the loss of biodiversity, depletion of natural resources, and global warming which together endanger food security and quality, ultimately encouraging suboptimal dietary patterns.
The consumption of a balanced diet rich in vegetables, fruits, legumes, whole grains, nuts, unsaturated fats, with minimal fish and poultry and no red meat, processed food, or sugar is believed to potentially bring about sustainability in human and environmental health.
Several PBDs that vary in terms of composition are known to be adopted worldwide, such as pesco-vegetarian, lacto-ovo-vegetarian, vegan, “dietary approaches to stop hypertension” (DASH), Mediterranean, new Nordic, and planetary diets.
Dietary patterns are driven by personal values, preferences, and food availability, and these aspects are in turn influenced by socioeconomic policies. Therefore, it is crucial to implement appropriate policies that support individual health.
To address this need, researchers reviewed the effects of PBD adoption on health, environment, and socioeconomic aspects, exploring whether a PBD can meet these targets, while providing recommendations for health policy.
Health and environmental impact of PBDs
Given the rise in the adoption of PBDs, it is crucial to examine their safety, advantages, and indications. Although long-term studies on the effect of PBD on weight management are limited, evidence from cross-sectional studies, systematic reviews, and meta-analyses suggests that the adoption of PBD supports weight loss and reduces body adiposity as compared to non-vegetarian and omnivorous diets.
Obesity is known to be a risk factor for non-communicable diseases such as cardiovascular disease (CVD) and type 2 diabetes mellitus (T2DM). Meta-analyses consistently highlight the benefits of PBDs in reducing the markers of CVD, such as total cholesterol, low-density lipoprotein, and apo-B, with no difference in triglyceride levels as compared to an omnivorous diets.
Although some studies provide contrasting evidence, in others, individuals on a PBD were found to have a 15% lower risk of CVD, with a reduced risk of CVD-related and all-cause mortality.
PBDs such as vegetarian diet, Mediterranean diet, and low-fat vegan diet are also shown to significantly reduce the levels of glycosylated hemoglobin (HbA1c) in T2DM patients as compared to omnivorous and energy-restricted diets.
While PBDs may increase the risk of deficiencies of vitamin B12, calcium, zinc, selenium, iron, niacin, and iodine, well-planned vegetarian diets including diverse food types may help achieve nutritional adequacy.
It is important to note that alternative plant-based foods such as juices, foods with added sugar, and fried foods are considered as unhealthy PBDs, and may lead to an increased risk of CVDs and T2DM.
Beyond health, dietary patterns are also shown to affect the environment. A shift from Western diets to PBDs is shown to result in reduced greenhouse gas emissions (22%), water use (18%), and land use (28%), indicating that lower consumption of animal-based foods and increased consumption of plant-based foods may result in lower environmental damage. However, the relationship between a shift to vegan diet and water use is yet to be studied thoroughly.
Affordability and acceptability
Several factors influence food choices, including social and cultural factors, individual taste preferences, education, as well as affordability, convenience, acceptability, and accessibility of food.
Evidence suggests that the transition from current diets to PBD is associated with an increased cost in low-middle income countries; therefore, PBDs may be easier to adopt in high-income countries.
PBDs are found to be more acceptable in low-middle income countries than high-income countries owing to socioeconomic, ethical, or religious reasons. Overall, an emphasis on a local and optimized diet is expected to drive the adoption of a sustainable dietary pattern which fulfills health- and environmental requirements.
Recommendations for policy makers
Findings from global studies call for the inclusion of environmental and sociocultural factors in the food-based dietary guidelines (FBDGs), beyond health-related factors alone.
In the future, FBDGs that integrate these aspects need to be developed by countries and disseminated to masses via media and education. Additionally, healthier food consumption can be encouraged through subsidies and taxation.
The present review focuses on the potential effects of adopting healthy PBDs on human and environmental health and sheds light on the barriers associated with such a shift.
The insights from this review highlight the need for a dialogue among scientists, policy makers, and other stakeholders to support the development of a coherent policy that outlines regionally acceptable and sustainable diets, thereby catering to the growing needs of the global population.