University of Sydney study links plant-based protein to longer adult life expectancy

A comprehensive global study has found that countries with higher consumption of plant-based proteins tend to have longer adult life expectancies than those relying more heavily on animal-derived proteins. The findings, published in Nature Communications, stem from an analysis led by researchers at the University of Sydney’s Charles Perkins Centre, who examined food and demographic data spanning nearly six decades and over 100 countries.

The study, conducted by Dr Alistair Senior, PhD candidate Caitlin Andrews, and a team of colleagues, analyzed the relationship between diet composition and longevity across a wide range of national contexts. By correcting for variables such as population size and gross domestic product, the researchers were able to isolate patterns suggesting that plant-based protein availability correlates with greater adult life expectancy on a population level.

“Our study suggests a mixed picture when it comes to comparing the health impacts of meat- versus plant-based protein at a population level,” said Andrews, lead author of the paper. “For children under five, countries with food systems rich in animal-based proteins and fats – such as meat, eggs, and dairy – showed lower rates of infant mortality. But among adults, the opposite pattern was observed, with plant-based protein associated with a longer life.”

The study utilized food supply and demographic data from the United Nations and other global databases covering the period between 1961 and 2018. The researchers examined 101 countries with diverse dietary patterns – from high animal-protein-consuming countries like the USA, Sweden, and Argentina to nations with more plant-focused diets such as Pakistan and Indonesia.

To ensure meaningful comparisons, the data was adjusted for economic differences and population size. The analysis showed that countries with greater access to plant-based protein sources – such as India – exhibited longer average adult life spans than countries with higher levels of animal protein in their food supply, including the United States.

“This study provides a long-term, population-level perspective on how the types of protein available in national food systems may influence longevity,” said Dr Senior, the study’s principal investigator. “It adds to the growing body of evidence suggesting that shifting toward plant-based sources of protein may support better health outcomes, especially later in life.”

The findings align with previous clinical and epidemiological research showing that high intake of animal-derived protein, particularly from processed meats, is associated with increased risk of chronic conditions such as heart disease, type 2 diabetes, and certain cancers. Conversely, plant-derived proteins – including legumes, soy products, whole grains, and nuts – are consistently linked to lower risk of these diseases and reduced overall mortality.

These associations have been supported by observations from global regions with high life expectancy and predominantly plant-based diets, including Okinawa (Japan), Ikaria (Greece), and Loma Linda (California, USA). The current study lends weight to these findings by assessing the relationship at a macro level across varied economic and cultural contexts.

As the global food system grapples with the dual challenges of population health and environmental sustainability, the study’s findings may inform both dietary guidelines and policy decisions. The production of plant-based proteins generally requires less land and water and emits fewer greenhouse gases than animal agriculture, making plant-based diets a more environmentally sustainable option.

“Protein is a crucial part of the human diet, but as eating habits change and developed countries look to decarbonize, where we get our protein from has come under greater scrutiny,” Dr Senior noted. “The knowledge that plant-based protein is associated with a longer life is really important as we consider not only how our diets impact our own longevity, but the health of the planet.”

While the study showed plant-based diets are associated with longevity in adults, it also acknowledged the benefits of animal proteins in reducing infant mortality. The researchers caution that public health strategies should be context-specific, especially in low- and middle-income countries where malnutrition and access to diverse food sources remain critical challenges.

“Our findings support the value of plant-based diets for adult longevity,” Andrews added. “But they also highlight the need for a nuanced approach when it comes to younger populations, where nutrient density and bioavailability – often higher in animal products – can be essential to healthy development.”

The study underscores the importance of balanced dietary planning and further research to optimize nutrition strategies that support health across all stages of life.