The July 6, 2021 issue of the Journal of the American Heart Association reported the finding of a trend toward a lower risk of sudden cardiac death in association with greater adherence to a Mediterranean diet during an average of 9.8 years of follow-up.* The study also uncovered a trend toward a higher risk of sudden cardiac death associated with greater intake of a Southern dietary pattern.

Sudden cardiac death, as defined by the National Heart, Lung, and Blood Institute-sponsored expert panel is “an unexpected death without obvious extracardiac cause, occurring with a rapid witnessed collapse, or if unwitnessed, occurring within one hour after the onset of symptoms.”

The current investigation included 21,069 participants in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study, which included men and women aged 45 years and older, among whom 42% were black. A high proportion of study participants resided in a region of the U.S. often referred to as the “stroke belt”. In previous research, five dietary patterns were derived from responses to dietary questionnaires administered upon enrollment in REGARDS. These included a pattern observed in the Southeastern United States that is characterized by added fats, fried food, eggs, organ meat, processed meat and sugar‐sweetened beverages. All subjects’ diets were subsequently scored for adherence to a Mediterranean diet, which included a high intake of vegetables, fruit, legumes, cereals and fish; a lower intake of meat and dairy products; a high ratio of monounsaturated fat to saturated fat consumption, and moderate alcohol intake. In-home examinations obtained physical measurements, information concerning medication use, a physical health summary, electrocardiographic evaluation, and blood and urine sample collection. Cardiovascular events and deaths were tracked via twice-yearly calls to participants or next of kin, and other methods.

During follow-up, 401 sudden cardiac deaths occurred. After adjustment for a number of factors, subjects whose Mediterranean diet scores placed them among the top one-third of participants had a risk of sudden cardiac death that was 26% lower than subjects whose scores were among the lowest third. The protective effect of the diet was limited to participants with no history of coronary heart disease at the beginning of the study.

Among men and women whose adherence to the Southern dietary pattern was among the top quarter of participants, the risk of sudden cardiac death was 46% higher than those among the lowest quarter.

“We know of no published studies investigating the possible associations of dietary patterns with risk of sudden cardiac death,” wrote authors James M. Shikany, DrPH, of the University of Alabama at Birmingham, and colleagues. However, they remarked that protective effects against the condition have been revealed in association with nuts and fish, which are Mediterranean diet components. They added that the omega 3 fatty acids in fatty fish have been proposed as responsible for the benefit observed in association with greater fish intake and may help protect against sudden cardiac death via their effects on resting heart rate, blood pressure, vascular endothelial function, triglyceride concentrations, inflammatory pathways and other factors. Furthermore, laboratory studies have revealed antiarrhythmic effects for omega 3s.

“Although observational in nature, these data suggest that diet may be a modifiable risk factor for sudden cardiac death and should be discussed with patients,” they wrote.  

*Shikany JM et al. J Am Heart Assoc. 2021 Jul 6;10(13):e019158.