Eating about two cups of beans or lentils and seven servings of whole grains daily, while eliminating red and processed meats, is linked to the biggest increase in lifespan—over two years—among dietary changes studied in young adults.
Evidence from Studies
No evidence studies found yet.
What Would Prove This
Per GRADE and EBM methodology, here is what ideal scientific evidence would look like to definitively prove or disprove this claim, ordered from strongest to weakest.
A systematic review and meta-analysis of prospective cohort studies with individual participant data could determine the independent association of each food group with mortality, adjusting for all other dietary components and confounders.
A systematic review and meta-analysis of 30+ prospective cohort studies with individual-level data, using standardized dietary assessment tools, adjusting for total energy intake, smoking, BMI, physical activity, and other food groups, and reporting all-cause mortality with hazard ratios per 100g/day increase in legumes, whole grains, and reduction in red/processed meat.
A long-term RCT could determine whether increasing legumes and whole grains while eliminating red/processed meat directly reduces mortality compared to a control diet.
A multicenter, double-blind, placebo-controlled trial randomizing 3,000 adults aged 20–25 to either a diet with +200g legumes/day, +225g whole grains/day, and 0g red/processed meat, or a control diet with typical Western intake, followed for 25 years with all-cause mortality as primary endpoint and dietary adherence monitored via biomarkers.
A large prospective cohort study could estimate the independent association of each food group with mortality after adjusting for other dietary and lifestyle factors.
A prospective cohort study following 15,000 adults aged 20–25 for 30 years, measuring dietary intake annually via validated food frequency questionnaires, adjusting for smoking, BMI, physical activity, and other food groups, and recording all-cause mortality.
A case-control study could compare past dietary habits of individuals who died prematurely versus those who lived to old age to assess whether higher legume and whole grain intake was more common among survivors.
A nested case-control study within a cohort of 50,000 adults, comparing dietary intake (via validated recall) in 2,000 individuals who died before age 70 with 4,000 matched survivors, adjusting for smoking, BMI, and physical activity.
A cross-sectional study could show whether individuals currently consuming high legumes and whole grains and no red/processed meat tend to live longer than those consuming typical diets.
A cross-sectional survey of 20,000 adults aged 20–80 measuring current diet via food diary and self-reported life expectancy, adjusting for age, sex, and socioeconomic status.