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.
Eating a healthier diet rich in fruits, vegetables, fish, and nuts would increase food costs for one person by about $550 a year, the researchers said. Diets rich in processed foods, meats and refined grains were considered unhealthy.
Among food groups, meats and protein showed the highest price difference and cost about 29 cents more per serving.
Previously, Mozaffarian's team suggested taxing less healthy foods together with subsidies for healthier foods would balance price differences.
"That's a real price difference, $1.50 for a low-income family could be an important barrier," Mozaffarian said in an interview. "On the other hand, that's a cup of coffee, that's a trivial cost compared to the enormous burdens of heart disease, obesity, diabetes that are due to poor diet."
The $1.50 per day is hugely significant for anyone working with budget constraints, said Valerie Tarasuk, a professor of nutritional sciences at the University of Toronto.
Tarasuk said nearly four million Canadians struggle to put food on the table because of a lack of money, based on data from Statistics Canada.
"We have to make sure everybody has the possibility of buying a healthy diet [that] is reasonably priced and we haven't done that now."
Tarasuk commended Newfoundland and Labrador's government, which in 2006, as part of the province's poverty reduction strategy, tied social assistance to inflation. "Indexing to inflation is huge," Tarasuk said.
The consequences of not addressing the problem appear in terms of higher health-care costs and low-income Canadians who are sicker and less productive members of society, she said.