Dr. Adam Drewnowski and colleagues from the University of Washington used a combination of nutrient profiling methods and national food prices data to create an "affordability index," which was then used to examine the nutrients per unit cost of 98 individual vegetables as well as five vegetable subgroups including dark green, orange/red, starchy, legumes (beans and peas) and "other" vegetables.
The results indicated while dark green vegetables had the highest nutrient density scores, after accounting for cost, starchy vegetables (including potatoes) and beans provided better nutritional value for the money.
Potatoes, in particular, provide one of the lowest cost options for four key nutrients including potassium, fiber, vitamin C and magnesium.
Among the most frequently consumed vegetables, potatoes and beans were the lowest-cost sources of potassium and fiber-nutrients of concern, as identified by the 2010 USDA Dietary Guidelines.
"The ability to identify affordable, nutrient dense vegetables is important to families focused on stretching their food dollar as well as government policy makers looking to balance nutrition and economics for food programs such as the school lunch program and WIC," lead researcher Adam Drewnowski, PhD said.
"And, when it comes to affordable nutrition, it's hard to beat potatoes," he said.
The study was funded by the United States Potato Board and adds to the growing database of nutrition science that supports potatoes in a healthful diet.
In addition, one medium-size (5.3 ounce) skin-on potato contains just 110 calories per serving, boasts more potassium (620g) than a banana (450g), provides almost half the daily value of vitamin C (45 percent), and contains no fat, sodium or cholesterol.
The study is published in the journal PLOS ONE.