Plant-based diets: should doctors be prescribing them?

A diet rich in fruit, vegetables, legumes and grains could help address looming issues like pandemics and health threats from a changing climate, according to an international, transdisciplinary review.

Written by 19 authors, including academics, medical doctors and dietitians, the review was recently published in the American Journal of Lifestyle Medicine.

Lead author Dr Komathi Kolandai, an honorary academic at COMPASS Research Centre at the University of Auckland, says Covid-19 exposed the limits of a reactive health system and showed the need for stronger prevention.

“Covid made clear that trying to manage the fallout of diseases after they occur is enormously costly,” says Kolandai. “We need to look seriously at modifiable lifestyle factors that can prevent or reduce disease risk.”

Even before Covid,  she says health systems were already under pressure from rising rates of non-communicable diseases and zoonotic infections (contagious diseases passed from animals to humans).

The pandemic intensified these challenges, adding substantial medical, social, and economic costs. Issues like long Covid, mental health distress, disrupted education, and increased medical waste all contributed to the long-term burden.

The review notes emerging evidence linking plant-based diets with reduced Covid-19 infection and severity, says Kolandai.

“Several earlier reviews found that people who adhered to healthy plant-based diets had lower rates of infection, hospitalisation, and severe outcomes. Some studies also suggested a reduced risk of long Covid.

“Most of the Covid research is observational, so we can’t claim causation,” she says. “But the consistency of the associations suggests plant-based diets may offer some protective benefit, and that’s worth exploring further.”
 

Beyond Covid, the review highlights well-established evidence showing that plant-based diets reduce the risk of major chronic diseases, including heart disease, type 2 diabetes, obesity, chronic kidney disease, and some cancers.

Modelling studies suggest that widespread dietary shifts could save billions in healthcare costs and add over a million quality adjusted life years worldwide.

The authors also link dietary patterns to the risk of future pandemics. The United Nations Environment Programme and other studies have identified high demand for animal protein, intensive livestock production, and wildlife trade as major drivers of zoonotic disease.

“Reducing reliance on animal-based foods could help lower the likelihood of new pathogens crossing into human populations. Preventing zoonotic spillover at its source is far more effective than trying to contain outbreaks after they occur,” says Kolandai.

Environmental impacts are another focus, she says.

“Animal-based foods account for more than half of global food-related greenhouse gas emissions, and studies show that shifting toward plant-based diets could cut emissions from agriculture by up to 60 percent in high income countries, and reduce land use, water use, and pollution.”
 

Kolandai says these changes would help mitigate climate-related health risks, including heat stress, respiratory illness, vector borne diseases, and climate-linked mental health issues.

The article notes that some hospitals in the US, the UK and Germany have already introduced plant-based meal programmes to promote health and reduce environmental impact.

The authors suggest health systems could go further by supporting plant-based diet prescriptions and integrating nutrition more fully into preventive care.

However, they admit major barriers remain, including limited nutrition training for physicians, inconsistent definitions of ‘plant-based diets’ in research, and unequal access to affordable, culturally appropriate plant-based foods.

Structural challenges within healthcare systems and cultural resistance to dietary change, especially in countries where meat is at the centre of most meals, are also significant.

“People can only make healthier choices if they are accessible, affordable, and supported by good information,” says Kolandai.

“That means improving nutrition education for clinicians and ensuring communities have the resources they need to adopt wholefood, plant-based eating if they choose to.”

Despite these challenges, the authors argue plant-based diets offer a potentially effective and multifaceted tool for reducing disease and its knock-on effects.

“Even modest dietary shifts could contribute to lower healthcare costs, by reducing the risk of future pandemics, chronic diseases and climate-related health threats,” they conclude.

The Potential of Plant-Based Lifestyle Interventions to Reduce the Burden of Disease in a Multi-Crisis Era by Komathi Kolandai, Nicholas Wright, Luke Wilson, Heleen Haitjema, Summer Rangimaarie Wright, Meika Foster, George Laking, Marissa Kelaher, Reen Skaria, Jennifer Douglas, Mok Keong Liew, Marion Leighton, Deborah Brunt, Fuchsia Gold-Smith, Mark Craig, Thomas Joseph, Wayne Hurlow, Cheryl Pittar and Sarah Mortimer has been published in the American Journal of Lifestyle Medicine.