This information is based on personal experiences and general knowledge. It is not professional medical advice. Always consult a healthcare provider before making changes to your diet, lifestyle, or treatment plans. This content was created with the assistance of AI tools to ensure thorough research and readability.
In 2019, Dr. David Katz, Dr. David Jenkins, and colleagues proposed a public health argument for updating how we define protein quality. The current definition, which emphasizes amino acid composition and digestibility, tends to favor animal protein. This has contributed to the impression that foods like meat, eggs, and dairy are more beneficial protein sources. However, this interpretation is not fully aligned with most current nutrition guidelines, which generally recommend increasing intake of plant-based foods for better overall health.
While protein deficiency remains a serious concern in some parts of the world, it is uncommon in high-income countries. In these regions, the primary public health concerns are chronic conditions such as heart disease, cancer, and type 2 diabetes, rather than protein deficiency.
A 2016 prospective cohort study conducted by Harvard researchers followed more than 130,000 adults over several decades. The study found that replacing animal protein with plant protein was associated with a lower risk of all-cause mortality. Strongest associations were observed when replacing processed meat (such as bacon) and egg protein, but even small shifts, such as substituting 3 percent of total energy from animal protein with plant protein, were associated with improved outcomes.
The researchers controlled for factors such as saturated fat intake, which suggests that the observed associations may be related to the protein sources themselves, not just accompanying fats.
One possible mechanism is that plant proteins are typically lower in branched-chain amino acids, which in excess have been linked in some research to insulin resistance and metabolic disorders. Another contributing factor may be the hormone IGF-1 (insulin-like growth factor 1), which has been associated with increased cancer risk and may be elevated by higher intakes of certain animal proteins. Some genetic studies suggest a causal role for IGF-1 in chronic disease, but more research is needed to fully establish this link in the context of diet.
Environmental exposures may also play a role. Persistent organic pollutants, such as dioxins and PCBs, tend to accumulate in animal tissues through the food chain. As a result, regular consumption of meat, fish, eggs, and dairy can contribute to a higher body burden of these compounds. Choosing more plant-based proteins may help reduce exposure to such contaminants.
Further support comes from the NIH-AARP Diet and Health Study, which included over 400,000 participants. The study reported that replacing a small portion of animal protein with plant protein was associated with a roughly 10 percent reduction in overall mortality. The largest benefits were observed when processed meats and eggs were reduced.
When analyzing multiple studies on dietary protein and mortality, the overall trend suggests that higher intakes of animal protein may be associated with greater risk of chronic disease and mortality, while plant protein intake tends to show the opposite association.
A 2020 meta-analysis concluded that increasing plant protein consumption could potentially contribute to a lower risk of premature death, and recommended that individuals be encouraged to shift toward more plant-based sources of protein for long-term health benefits.
Resources:
- NutritionFacts.org
- Personal Knowledge
