Abstract P329: Low-carbohydrate Diets and Incidence, Prevalence, and Progression of Coronary Artery Calcium in the Multi-ethnic Study of Atherosclerosis (mesa)

Abstract

Background: The coronary artery calcium (CAC) score is associated with the risk of coronary heart disease. We aimed to assess the relationship between low-carbohydrate dietary patterns and CAC scores in the MESA cohort. Methods: Our sample included 5,702 men and women who were free of clinical cardiovascular disease and had food frequency questionnaires at baseline (2000-2002), and at least one measure of CAC during follow-up. We excluded those with implausible energy intake (<600 kcal/day or >6000 kcal/day) or daily physical activity (>24 hours). Two low-carbohydrate-diet (LCD) scores were generated: an overall LCD score was calculated based on total carbohydrate, fat, and protein, and a plant-based LCD score was calculated using intakes of unsaturated fat (excluding trans fat) and vegetable protein. CAC scores at exam 1 and at 2 and 3 (18 and 36 months later) were used in multivariable relative risk regression models to examine the association between LCD scores and CAC prevalence and incidence (binary), while robust regression was used to examine CAC progression (continuous). Analyses were adjusted for demographic, socioeconomic, lifestyle, and cardiovascular risk factors. Results: The mean age was 62 years, 48% of participants were male, and 40.8% were White. The mean (SD) levels of carbohydrate intake as a percentage of energy were 64.2 (5.2), 56.1 (4.9), 51.5 (3.7), 47.5 (4.0), and 42.1 (5.6) from the lowest to the highest quintiles of the overall LCD score. There were 2,652 (46.5%) participants who had positive CAC scores at baseline and 252 participants who had newly positive scores for CAC during follow-up. Among those with prevalent CAC at baseline, the median (IQR) of increases in CAC was 47 (132) over follow-ups. For incident CAC, relative risk estimates (95% CI) from Quintile 1 to 5 were 1, 0.73 (0.52, 1.02), 0.65 (0.45, 0.95), 0.90 (0.63, 1.28), 1.05 (0.77, 1.42) for overall LCD scores, and were 1, 1.14 (0.81, 1.61), 0.98 (0.71, 1.37), 1.08 (0.78, 1.49), 1.15 (0.82, 1.62) for plant-based LCD scores, respectively. No significant trend was observed for associations with incident CAC. There was no significant association between any LCD score and CAC prevalence or progression among those with positive CAC scores at baseline. Conclusions: A low-carbohydrate diet, including a plant-based low-carbohydrate diet, was not associated with prevalence, incidence, or progression of CAC among those with prevalent CAC at baseline.