Adults who consume more plant-based than animal-sourced proteins have longer life expectancies, according to a recent study spanning 101 countries. The research analyzed publicly available demographic data between 1961 and 2018. 

“Higher animal-based protein supplies were associated with enhanced survivorship during infancy and early childhood, independent of total calorie supplies, while plant-based protein-rich environments were associated with improved survivorship in later life and overall life expectancy at birth,” the study reveals. 

The Australian study highlights the importance of considering the health impacts of diets on longevity and the planet.

First author and Ph.D. candidate at Charles Perkins Centre, Caitlin Andrews, says: “Our study suggests a mixed picture when it comes to comparing the health impacts of meat versus plant-based protein at a population level.”

“For the under-fives, a food system that supplies large amounts of animal-based proteins and fats, such as meat, eggs, and dairy, lowered rates of infant mortality. However, for adults, the reverse was true, wher plant-based proteins increased overall life expectancy.”

According to the analysis, low total protein levels were consistently linked to lower life expectancy and survivorship.

Animal vs. plant proteins

According to the researcher, published in Nature Communications, high levels of animal-based protein, especially processed meat, are a known cause of chronic conditions such as cardiovascular disease, type 2 diabetes, and some types of cancer.

They tout that plant proteins, such as legumes, nuts, and whole grains, are linked to lower risk of chronic diseases and overall mortality rates as seen in the most long-lived communities — Okinawa in Japan, Ikaria in Greece, and Loma Linda in California, US.

“Protein is a crucial part of the human diet, but as eating habits change and developed countries look to decarbonize, wher we get our protein from has come under greater scrutiny,” comments lead investigator Dr. Alistair Senior at Charles Perkins Centre.

“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 also the health of the planet.”

Resource-scarce regions

The researchers address the question of adequate protein in resource-scarce regions, suggesting plant-based proteins can help fill nutritional gaps wher animal-based proteins are unavailable. However, to support early life development, such diets must be balanced and may require supplementation to avoid deficiencies — particularly in vitamin B12, which is critical for infant growth and is largely found in animal-based foods.

They discovered no discernible difference between plant-based and animal-based protein sources in low-fat environments, and that early life survivorship decreased when overall protein supplies were low. Low-fat environments refer to nutritional environments wher overall dietary fat and energy (calorie) availability are limited.

“In higher fat environments (i.e., with sufficient net calories), increasing animal-based protein supplies showed a distinct advantage for early life survivorship over plant-based protein. This suggests a possible link between essential nutrient availability and survival up to age five,” reads the paper.

“A possible explanation for this result is that animal-based protein may offer some advantages over plant-based protein in terms of bioavailability, digestibility, and essential amino acid content.”

They add that animal-based proteins are also rich in iron, zinc, and vitamin A, essential for growth and development.

“While our findings reinforce the benefits of animal-based protein for early life survivorship, it is crucial to acknowledge the potential role of plant-based protein, particularly in resource-constrained environments,” reads the paper.

“In these settings — specifically, regions with limited animal-based protein and fat supplies — our results indicated that adding energy from any protein source, plant or otherwise, was beneficial. This supports the idea that our findings do not refute the advantage of incorporating plant-based protein in a malnourished environment.”

According to the researchers, plant-based proteins can be tailored or combined to meet nutritional needs in low-resource settings. 

Plant proteins for longer life

One explanation of plant-based proteins and longer life expectancy is high dietary fiber and whole grain content.

“High intake of whole grains has been linked to decreased risks of mortality from all causes, cardiovascular disease, and cancer in the general population,” reads the study.

The authors flag rising urbanization and increasing consumption of meat, sugar, fats, oils, and processed foods, especially in areas with higher socio-demographic indices, wher animal-based protein from ultra-processed foods enjoys greater access.

“Numerous studies have consistently linked high intake of processed foods to an increased risk of age-related ill health and premature death, providing a plausible explanation for the negative impact on later-life survivorship observed in animal-based protein-rich environments compared to plant-based protein-rich ones,” the researchers note.

“Maximal survivorship to age 60 and overall life expectancy at birth were observed in nutritional environments with lower fat supplies and a higher proportion of protein from plant-based protein sources.”