The staples of a healthful diet may come at too high a price — literally — for some Americans.

With the nation's revised federal dietary guidelines in mind, researchers at the University of Washington School of Public Health surveyed more than 1,000 King County residents on their eating habits and how much they spend to maintain them.

The researchers matched food consumption with prices at three of Washington's largest supermarket chains — Albertsons, Safeway and Quality Food Centers — and determined how much it would cost to swap out some of the sugar-laden and fatty foods for the fresh fruits, veggies and whole-grain breads pushed in the dietary guidelines.

Among the findings of the study, released Thursday:

People who ate the most junk food paid the least for groceries but were the furthest from meeting the recommended intake of healthful nutrients. They also exceeded the recommended levels of saturated fat and sugars, which have been linked to chronic diseases such as obesity and diabetes. Those who spent the most on groceries ate the healthiest, coming closest to meeting the dietary guidelines.

The latest guidelines, released last year by the U.S. Department of Health and Human Services and the Department of Agriculture, focus on balancing calories with physical activity and getting enough of the nutrients that Americans generally consume in inadequate quantities, including potassium, fiber, vitamin D and calcium. Revised every five years, the guidelines form the basis of school-meal programs, Meals on Wheels for the elderly and other nutrition programs.

Participants in the study had an average daily intake of 2,800 milligrams of potassium, 700 milligrams short of what the new guidelines recommend. Buying enough fresh fruit to bridge that gap alone would cost the average person an additional $380 a year, the study found.

Bridging the gap in the average intakes of vitamin D and fiber would add about $250 a year.

"It shouldn't cost more to eat a nutritious diet," said Pablo Monsivais, lead author of the study, which was published in the August issue of the journal, Health Affairs. "For many families it's still too costly to build their diets around fresh vegetables and fruit."

Experts add that when the pocketbook is stretched, it's usually fresh produce and other healthful foods that are first to be scratched from household shopping lists.

"We need to find ways to make necessary nutrients available and affordable," Monsivais said, adding that while prices for items like fruits and vegetables have increased over the last few years, foods high in added sugars, sodium and saturated fats have seen a far more modest increase.

To address this disparity, the UW researchers are recommending education campaigns to lead consumers to low-cost but good-tasting and readily available sources of nutrients.

"Dried prunes are great sources of potassium, but unless you launch a major PR campaign to increase their popularity, no one's going to eat them," Monsivais said.

There is also the need to tell consumers how to find the cheapest source of nutrients, he said. Nectarines, for example, are a great source of potassium but are more expensive than bananas, which are not only rich in potassium but are a good source of calcium, too.

The study also recommends a careful examination of programs such as the Supplemental Nutrition Assistance Program, or SNAP, formerly known as food stamps, to see if they are consistent with federal nutritional guidelines.

Monsivais is quick to point out that some private and nonprofit businesses already are helping low-income Americans meet these dietary recommendations. At some farmers markets, for examples, shoppers can use their SNAP card — a plastic debit card that can be used at participating retailers — to buy fresh meat, bread and produce.

"People on low incomes should have the same access to good, fresh food as anyone," said Chris Curtis, director of the Neighborhood Farmers Market Alliance, a nonprofit that oversees seven farmers markets in Seattle, all of which have been accepting SNAP since 1994. "It's a way to increase revenue, but it's also the principle."

Of the 41 farmers markets in King County (18 of them in Seattle), more than half accept SNAP cards. Within Seattle, Pike Place Market is one of only three that doesn't accept SNAP cards, but it expects to in the next several months. The county, too, is working toward increasing participation in SNAP and other federal nutrition programs.

"This is great for the people that grow our food and the people that need it," Monsavais said. "It's a step in the right direction."

Roberto Daza: 206-464-3195 or rdaza@seattletimes.com