High-protein diets and cancer risk: what new research really says — and what Thai readers should know
A high-profile scientific study that linked heavy protein intake in middle age to higher cancer deaths has reawakened debate about popular high‑protein diets. Researchers who analysed a large US nutrition survey and ran complementary animal and cellular experiments reported that people aged about 50–65 who consumed a high proportion of calories from protein — particularly animal protein — had a markedly higher risk of dying from cancer over the following years, and that lower protein intake reduced levels of the growth factor IGF‑1 and slowed tumour growth in mice (Levine et al., 2014). At the same time, a more recent umbrella review of systematic reviews and meta‑analyses (published in 2024) concluded that the overall human evidence linking total protein intake to cancer risk is limited and inconsistent, finding no clear association for several cancer types and rating the certainty of evidence as “possible” or “insufficient” for most outcomes (Kühn et al., 2024). For Thai readers weighing the claims, the picture is nuanced: biological mechanisms exist and animal experiments are persuasive, but human epidemiology is mixed — and source of protein (animal vs plant), age and health status matter. Below I unpack the findings, explain why results differ, give perspectives from the literature, and offer practical, Thailand‑relevant advice.