Low-Carbohydrate Diet Score and Coronary Artery Calcium Progression: Results From the CARDIA Study

To investigate whether low-carbohydrate diets (LCDs) were associated with coronary artery calcium (CAC) progression. APPROACH AND RESULTS: We included the participants who completed computed tomography assessment of baseline CAC in 2000 to 2001 (year 15) and follow-up (year 20 or 25) and food frequency questionnaire (years 0, 7, and 20) in the CARDIA study (Coronary Artery Risk Development in Young Adults). CAC progression was defined as CAC >0 at follow-up among participants with baseline CAC of 0 and an annualized change of 10 or percent change of ≥10% for those with 0<baseline CAC<100 or baseline CAC≥100, respectively. Among 2226 included participants (age, 40.4±3.5 years; 45.4% men), the carbohydrate intake accounted for 47.8±6.5% of total energy, and 204 (9.2%) had CAC at baseline (year 15). Over a mean follow-up of 8.3 years, 591 (26.5%) participants had CAC progression. After adjustment for traditional cardiovascular risk factors and other dietary factors, carbohydrate intake as a percentage of total energy was inversely associated with the risk of CAC progression (hazard ratio, 0.731 [95% CI, 0.552–0.968]; P=0.029). Furthermore, the animal-based but not plant-based LCD score was significantly associated with a higher risk of CAC progression (animal-based LCD score: hazard ratio, 1.456 [95% CI, 1.015–2.089]; P=0.041; plant-based LCD score: hazard ratio, 1.016 [95% CI, 0.821–1.257]; P=0.884; both comparing extreme groups). CONCLUSIONS: LCDs starting at a young age are associated with an increased risk of subsequent CAC progression, particularly when animal protein or fat are chosen to replace carbohydrates. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT00005130.