A family on a healthy diet can expect to pay $2,000 more a year for food than one having less nutritious meals, say researchers who recommend that the cost gap be closed.

The research in Thursday’s issue of British Medical Journal Open reviewed 27 studies from 10 high-income countries to evaluate the price differences of foods and diet patterns.

“Our results indicate that lowering the price of healthier diet patterns — on average about $1.50/day more expensive — should be a goal of public health and policy efforts, and some studies suggest that this intervention can indeed reduce consumption of unhealthy foods,” Dariush Mozaffarian, the study’s senior author and a professor at the Harvard School of Public Health and his co-authors concluded.