Personal and Planetary Health – The Role of Plant-Based Diets

Would it surprise you to learn that personal and planetary health are connected? Increasing consumption of animal products and its environmental impact are important factors in tackling climate change. A notable new study suggests that moving towards sustainable diets requires reducing animal protein and increasing plant-based foods. These changes would improve personal health by lowering chronic disease risk while also supporting the health of our planet.

Poor Diet – From Chronic Disease to Global Warming

Worldwide, humanity faces both chronic diseases linked to poor nutrition and the effects of climate change. The available evidence makes it clear that it is time to change dietary patterns and focus on foods that benefit health.

Growing animal protein consumption is driving further expansion of livestock farming. Globally, three times as much meat and twice as much milk are produced as 50 years ago. This demand destroys ecosystems suitable for agriculture to create livestock grazing land and increases animal feed production. Animal products and their supply chains contribute to greenhouse gas emissions, including carbon dioxide, methane and nitrogen oxides.

The livestock sector produces 50% of atmospheric methane and 60% of nitrogen oxides. Compared with carbon dioxide’s global warming effect, methane is 25 times more potent and nitrogen oxides 298 times more potent. Global Warming Potential (GWP) measures a greenhouse gas’s ability to retain heat when released into the atmosphere relative to carbon dioxide. Carbon dioxide’s GWP is set at 1. Other gases’ GWP values vary according to how effectively they retain heat and how long they remain in the atmosphere.

With time running out to address climate change, the Paris Agreement adopted in 2016 aimed to limit warming to below 2°C above pre-industrial levels, ideally 1.5°C. The agreement is legally binding internationally. The United Nations Climate Change Conference has recognised climate change as a global emergency, and the American Medical Association (AMA) has described it as a public health crisis.

According to the EAT-Lancet Commission, moving to healthy, sustainable diets by 2050 will require halving global red meat consumption and doubling consumption of nuts, fruit, vegetables and pulses. This is an important step towards reducing livestock-related greenhouse gas emissions and limiting global temperature rises. Even eliminating fossil fuel emissions would not be enough: emissions from the global food system alone would prevent the Paris Agreement targets from being met. The Intergovernmental Panel on Climate Change therefore recommends major shifts towards sustainable plant-based diets.

Diet as a Leading Cause of Chronic Disease

Dietary choices are the biggest cause of chronic disease. Many studies associate plant-based diets with lower rates of obesity, cardiovascular disease, diabetes, chronic kidney disease and cancer. They have also been associated with lower COVID-19 risk and milder illness. Historical evidence suggests that ongoing industrial animal farming practices could lead to future pandemics.

Carbon dioxide equivalents (CO2eq) measure a greenhouse gas’s global warming potential in terms of carbon dioxide. Plant proteins such as pulses and soy produce less than 1 CO2eq per 28 g dry serving, compared with 1200 CO2eq for beef and 200 CO2eq for pork at the same weight. Overall, global greenhouse gas emissions from animal foods are twice those from plant foods. Animal food production, including feed, accounts for 57% of food-related emissions, compared with 29% from plant foods. Moving towards more plant-based diets consistent with standard dietary recommendations could reduce global mortality by 6% to 10% in 2050 and food-related greenhouse gas emissions by 29% to 70%.

National dietary guidelines could incorporate the environmental effects of food choices. A recent study assessed guidelines from 83 countries and found that only 45%, representing approximately 17% of the world’s population, were compatible with environmental sustainability. Adopting low-meat dietary patterns could substantially reduce premature deaths, by 19% for a flexitarian diet, for example. This evidence provides compelling reasons for governments to invest in healthier, environmentally friendly dietary programmes.

Companies in the livestock, food and pharmaceutical sectors may avoid recommending healthy dietary changes because these may not serve their interests. Medical professionals therefore have an important role in advocating measures and supporting legislation to protect planetary health. Healthcare workers have a duty to inform and guide patients, families and communities about dietary changes that could affect their lives. This is an important responsibility towards future generations and the planet.