Using twins allowed team members to assess the influence of the diet on HRV while controlling for genetic and other familial influence.

Among the study's key findings:

Measurements of HRV showed that the higher a person's diet score, the more variable the heart beat-to-beat time interval - 10 percent to 58 percent (depending on the HRV measure considered) for men in the top Mediterranean diet score quarter compared to those in the lowest quarter; this equates to a 9 percent to 14 percent reduction in heart-related death. Genetic influence on HRV frequency ranged from 20 percent - 95 percent, depending on the HRV measure considered.

The study cannot be generalized to women or other ethnic groups because 94 percent of participants were non-Hispanic white males.

Source: American Heart Association