Scientists hit an impasse this year in their attempt to update the Recommended Dietary Allowances -- the guidelines for consumption of certain vitamins and minerals.

The National Research Council -- part of the National Academy of Sciences -- grappled with revising the RDAs since spring, and an early draft suggested that they were going to change requirements for several nutrients -- increasing calcium and decreasing vitamins A, B6, C and iron.

In the end, however, National Research Council Dr. Frank Press reported to Dr. James Wyngaarden, head of the National Institutes of Health, that there would be no 10th edition of the RDAs in October. The impasse, Press said in a letter to Wyngaarden, resulted from "scientific difference of opinion between the committee, scientific reviewers appointed by the Research Council and additional reviewers from the Food and Nutrition Board."

The National Research Council appointed a new committee to resolve the scientific questions at issue. In the meantime, Press wrote, "the public and the scientific community at large should rest assured that there is no cause for concern and that they may continue to place confidence in the RDAs that have been in effect for the past five years."

Although the National Research Council couldn't decide on new RDAs, there was agreement on another nutritional issue: cholesterol. During a consensus conference sponsored by the National Institutes of Health, scientists laid the foundation for a major drive to lower blood cholesterol levels nationwide.

As part of that effort, the National Heart Lung and Blood Institute initiated a Cholesterol Awareness Program in November. Patterned after another successful education program to lower blood pressure, the cholesterol program is teaching Americans to "have their blood cholesterol checked, to know their cholesterol levels and to understand the implications of their cholesterol reading," said Dr. Claude Lenfant, NHLBI director.

Americans have some of the highest blood cholesterol levels in the world. That's one major reason, scientists say, that heart disease remains the number one killer in the United States today. The national goal is for people 30 years and younger to maintain blood cholesterol at 180 milligrams or lower; those over 30 years of age should aim for blood cholesterol levels of 200 mg and below.

People can reduce their blood cholesterol by eating fewer foods that contain high levels of cholesterol and saturated fat; by exercising; and by losing weight. Even a 10 percent across-the-board reduction in cholesterol for Americans could save an estimated 100,000 lives a year, researchers say.

Other nutrition news was made at a consensus conference in January on the "Health Implications of Obesity." Again, the message to consumers: keep at ideal weight for age, sex and height or face increased risk of health problems.