Cardiovascular disease risk under low-fat, Mediterranean, and American Heart Association diets: a target trial...

The Mediterranean diet reduces cardiovascular disease (CVD) risk in European populations, but its long-term effectiveness in United States adults, particularly relative to the American Heart Association (AHA)-2020 dietary goals, remains uncertain.

We compared 20-y CVD risk in United States adults under sustained adherence to a low-fat diet, a Mediterranean diet, and the food-based AHA-2020 dietary goals.

We emulated a target trial using data from the Nurses' Health Study and Health Professionals Follow-up Study among 12,197 United States adults aged 55 to 80 y with diabetes or ≥3 major CVD risk factor. Diet was assessed every 4 y via validated food frequency questionnaires. The primary outcome was CVD, defined as nonfatal myocardial infarction, coronary revascularization, stroke, and CVD death, confirmed by medical records. We applied the parametric g-formula to estimate 20-y CVD risk under each dietary strategy.

Over 20 y, 3469 CVD cases occurred (1451 men and 2018 women). Pooled absolute risks of CVD were 35.9% (95% CI: 33.1%, 38.5%) under the low-fat diet, 28.2% (95% CI: 25.8%, 31.4%) under the Mediterranean diet, and 31.2% (95% CI: 29.1%, 33.4%) under the AHA-2020 dietary goals. Compared with the low-fat diet, estimated risk ratios were 0.79 (95% CI: 0.70, 0.91) for the Mediterranean diet and 0.87 (95% CI: 0.79, 0.96) for the AHA-2020 dietary goals. In a general population not selected for age, diabetes, or CVD risk factors, the corresponding risk ratios were 0.90 (95% CI: 0.84, 0.95) and 0.94 (95% CI: 0.90, 0.99), respectively.

Sustained adherence to the Mediterranean diet and the AHA-2020 dietary goals is estimated to have a lower 20-y risk of CVD than a low-fat diet in United States adults.