A new Harvard analysis of the best evidence available on the price differences between the healthiest and unhealthiest diets finds that on average, individuals need to spend about $1.50 more per day, or around $550 a year, to keep to the healthiest diets.

Writing in the latest issue of BMJ Open, researchers from Harvard School of Public Health (HSPH), Boston, MA, say their findings highlight “the challenges and opportunities for reducing financial barriers to healthy eating.”

Lead author Mayuree Rao, a junior research fellow in the Department of Epidemiology at the school, says:

“People often say that healthier foods are more expensive, and that such costs strongly limit better diet habits. But, until now, the scientific evidence for this idea has not been systematically evaluated, nor have the actual differences in cost been characterized.”

For their study, the researchers performed a systematic review and meta-analysis of 27 studies published between 2000 and 2011 that included prices of individual foods and healthy and unhealthy diet patterns in 10 rich countries.

For individual foods, they worked out the price difference per serving and per 200 calories. For diet patterns, they worked out the price difference per day of consuming 2,000 calories, the recommended daily calorie intake for adults in the US.

They found that the healthiest diets, for example those rich in fruits, vegetables, nuts and fish, cost on average significantly more than the unhealthiest ones, such as those rich in processed foods, meats and refined grains.

The average extra cost per day of the healthiest diet patterns was about $1.50 more, compared with the unhealthiest ones. Over a year this amounts to just under $550 per person.

Among the food groups, meat and protein foods had the largest price differences, with healthier options costing $0.29 per serving and $0.47 more per 200 calories than less healthy ones.

Price differences (healthy minus unhealthy) per serving were small but significant for grains (+$0.03), dairy (-$0.004), snacks and sweets (+$0.12) and fats and oils (+$0.02).

Senior author Dariush Mozaffarian, an associate professor at HSPH and Harvard Medical School, says while they found healthier diets did cost more, the difference was not as big as one might expect.

And, while this “would represent a real burden for some families, and we need policies to help offset these costs,” he adds:

“On the other hand, this price difference is very small in comparison to the economic costs of diet-related chronic diseases, which would be dramatically reduced by healthy diets.”

He and his colleagues suggest one reason unhealthy diets are cheaper is because food policies support the production of cheap, high volume commodities, and this has resulted in a complex system that produces, stores, transports, processes and markets food so as to “favor sales of highly processed food products for maximal industry profit.”

This now needs to be balanced with a similar system that supports the production of healthier foods so as to increase the availability and reduce the prices of healthier diets, they urge.

Funds from the National Heart, Lung, and Blood Institute, the National Institute of Diabetes and Digestive and Kidney Diseases, and HSPH helped finance the study.

Meanwhile, another HSPH team reported recently in the Journal of Nutrition Education and Behavior that the Supplemental Nutrition Assistance Program (SNAP), the largest federal nutrition program, is failing to improve dietary quality.