The dean of American consumer reporters, Sidney Margolius, died last week of a heart attack at a New York hospital. Margolius, who was 67, lived in Port Washington, L.I.

It was from his home that he wrote consumer columns, syndicated by the North American Newspaper Alliance, and carried in over 100 union daily newspapers. But his career as a consumer journalistbegan 40 years ago when he became consumer editor of PM, a New York City newspaper.

Margolius was always ahead of his time. Ten years ago when many consumer leaders were pushing for nutrition labeling on foods, Margolius said the information would not be particularly useful. What would be useful, he said, was percentage of ingredients labeling so people would know just how much pork is in pork and beans. Today the government, as well as many nutritionists have come to similar conclusions.

Margolius, who wrote 20 books, was perhaps best known for his first and his last two: "The Consumers Guide to Better Buying" sold a million copies. "Health Food Facts and Fakes," put the world of food supplements into a perspective it never had before and hasn't had since. "The Great American Food Hoax" became the bible for many young consumer reporters. To this day, much of the information he compiled in that book has never been duplicated.

To the breed of consumer reporters who came along 30 years after Margolius had made his mark, he was always more than generous with his time and his information.

Margolius was a member of President Johnsons's Consumer Advisory Council and served on the board of Consumers Union.