Most elderly Americans know they need a sensible diet to stay healthy, but one in five say they skip at least one meal a day, according to a survey by Nutrition Screening Initiative, a five-year project launched by a coalition of medical, health care and senior citizens' groups.

The survey also found that 45 percent of senior citizens take more than one prescription drug, which can affect appetite or absorption of nutrients. And one in four of the 802 people over 65 surveyed had a household income of less than $10,000.

"Nutrition is one of the important vital signs, just {like} blood pressure or pulse," said Gerald Keller, an official of the American Academy of Family Physicians, a leader of the coalition. "The fact is, however, America has not effectively incorporated routine nutrition screening and care into the nation's system of health care delivery," he said.

The elderly face a disproportionate nutritional risk for a variety of reasons. Some are poor. Many live alone and tend not to cook for themselves, while others have reduced appetite and sense of taste, sometimes because of the medications they take, according to Paul Kerschner, senior vice president of the National Council on the Aging.