Healthier diets including vegetables, fruits, whole grains and low-fat dairy products may be too expensive for many U.S. families, researchers say. New federal dietary guidelines for Americans stress the need for Americans to consume more potassium, dietary fiber, vitamin D and calcium and get fewer calories from saturated fat and added sugar, researchers say. Lead researcher Pablo Monsivais, an assistant professor at the School of Public Health at the University of Washington and colleagues Anju Aggarwal, and Adam Drewnowski surveyed 1,318 adults in King County, Wash., about their diet. \"Specifically, we examined the cost of each incremental increase in intake for dietary fiber, potassium, calcium and vitamin D and we also examined the cost impact of reducing consumption of added sugar and saturated fat -- two calorie sources the committee specifically recommended limiting,\" the researchers say in a statement. The study, published in the journal Health Affairs, found increasing consumption of just potassium -- the most expensive of the four recommended nutrients -- would add $380 per year to the average consumer\'s food costs. However, each time consumers obtained 1 percent more of their daily calories from saturated fat and added sugar, their food costs significantly declined, the study found. The researchers also found that families that spent the least amount of money had the lowest levels of the recommended nutrients, but had the highest levels of saturated fat and added sugar.