A healthy diet is expensive and could make it difficult for Americans to meet new U.S. nutritional guidelines, according to a study published Thursday that says the government should do more to help consumers eat healthier.

An update of what used to be known as a food pyramid in 2010 had called on Americans to eat more foods containing potassium, dietary fiber, vitamin D and calcium. But if they did that, the journal Health Affairs said, they would add hundreds more dollars to their annual grocery bill.