The Food and Drug Administration is beginning a campaign to try to persuade Americans to cut excess salt out of their diets to help prevent high blood pressure and other ailments.

Dr. Mark Novitch, acting deputy FDA commissioner, told a House subcommittee that the sodium humans consume is mostly in the form of ordinary salt. Half the sodium Americans consume comes from prepared foods, half from their salt shakers.

The new FDA commissioner, Dr. Arthur Hull Hayes, has approved a five-point plan to:

Propose rules requiring disclosure of the amount of sodium in foods that already carry nutrition labeling, and to define "low" and "reduced-sodium" products better.

Consider seeking legislative authority to require sodium labeling on many more foods.

Continue an effort to have food processors voluntarily reduce the salt in hundreds of heavily salted prepared foods.

Try to teach the public the dangers of too much salt.

Monitor Americans' sodium intake to see whether the anti-salt campaign is working.

"We are encouraged," Novitch said, because some food processors have begun to reduce salt content. But "what is needed and what we propose," he said, is a coordinated effort to minimize the harm salt can do, while preserving its needed and desirable uses as a flavor and preservative.

Doctors told the House science and technology subcommittee Monday that no one knows exactly how salt affects blood pressure. But there is no doubt, they said, that cutting salt intake can bring blood pressure down to normal in many of the 23 million people with high blood pressure.

Craig Claiborne, food editor of The New York Times, on a low-salt diet for two years because of high blood pressure, said he has a hard time finding canned and other processed foods without added salt. He urged a health warning on high-sodium products like that on cigarette packages.