Are beans and legumes good for longevity?
Large observational studies consistently show that people who eat more legumes have a lower risk of death. For most people, a daily serving of legumes is well supported by the evidence; older adults should also pay attention to getting sufficient protein overall.
Eating more legumes is associated with a lower risk of death. That is the finding of a meta-analysis of 32 cohort studies involving more than 1.1 million people: for every additional 50 grams per day, the risk of dying falls by around 6%. The researchers themselves describe the certainty as low to moderate. The evidence comes almost entirely from observational studies in which people are followed rather than assigned to groups1.
The same meta-analysis also found lower stroke mortality at higher intakes, but that was based on only five studies. For cardiovascular disease and cancer, the associations were not statistically significant. A US cohort study of more than 521,000 people followed over 16 years adds something: replacing animal protein with legumes or nuts was associated with lower mortality, including from cardiovascular disease and cancer2.
Legumes appear consistently in dietary patterns associated with longer life expectancy. A review article identifies them as one of the most frequently recurring features of such patterns, across a range of different diets3. A modelling study covering seven countries estimates that 40-year-olds who sustainably switch to eating more legumes, whole grains and nuts while reducing red meat could gain around 6 to nearly 10 extra years. These are model calculations for an entire dietary pattern, not a direct measurement of legumes alone4.
For older adults there are some particularly relevant figures. In a Chinese cohort study of more than 13,000 people aged 65 and over, those who followed a healthy plant-based diet, with legumes as an important component, had a 19% lower risk of dying. Those who followed an unhealthy plant-based diet had a 17% higher risk. The quality of plant-based eating therefore matters, not just its plant-based nature5.
Two points to bear in mind. Adults over 65 have a relatively higher protein requirement. Legumes provide somewhat less protein, and somewhat less complete protein, than animal sources, so keeping track of total protein intake is worthwhile6. For people with chronic kidney disease, consulting a doctor or dietitian is advisable, but there is also good news: the phosphate in legumes is absorbed less efficiently than the phosphate found in processed foods, making legumes relatively more favourable for kidney patients7.
All claims are drawn from observational studies (cohort studies and meta-analyses of those studies) and modelling calculations. No randomised controlled trials measuring long-term mortality exist. Confounding by other lifestyle factors cannot be excluded. The certainty of the evidence was rated by the authors themselves as low to moderate.