Diets closer aligned with nutritional guidelines could lower the risk of several chronic conditions and improve economic outcomes, such as employment and healthcare costs. However, little is known about the range, order of magnitude and timing of these potential effects.

We used a microsimulation approach to predict US population changes over 30 years in health and economic outcomes that could result from a substantial (but not impossible) improvement in diet quality – an improvement from the third to the fifth quintile of US scores on the Alternate Healthy Eating Index, 2010 version.

Risk ratios from the literature for diabetes, heart disease and stroke were used to modify the Future Adult Model (FAM) to simulate outcomes from a higher-quality diet. Model parameter uncertainty was assessed using bootstrap and sensitivity analysis examined the variation in published risk ratios.

FAM simulates outcomes for the US adult population aged 25 and older.

Improved diet quality initially leads to very small changes in chronic disease prevalence, but these accumulate over time. If diets improved beginning in 2019, after 30 years diabetes prevalence could be reduced by 5·9 million cases (11·5 %), heart disease prevalence by 4·0 million cases (7·2 %) and stroke prevalence by 1·9 million cases (10·3 %). These reductions in disease prevalence would be accompanied that same year by fewer deaths (88 000) and healthcare cost savings of $144·0 billion (2019 USD).

This microsimulation study suggests that improvements in diet are likely to improve health and economic population outcomes over time.