There is no good evidence that artificial food colorings cause hyperactivity in children or that such children benefit from the "Feingold diet," which is free of these additives, an expert committee maintained yesterday.

The conclusion was immediately disputed by some scientists, including one committee member, and by a nationwide association of parents of hyperactive children. These parents and their Feingold Association contend that 20,000 children are being helped by the diet, and that the committee's sponsor, the Nutrition Foundation, is industry-dominated.

"Hyperactive" or "hyperkinetic" children move about so much and have so short an attention span that they cause serious and often tragic problems at home and school and often learn very poorly.

In 1973 Dr. Ben Feingold, a respected San Francisco allergist, began saying that about half such children can be "dramatically" helped by diets free of artificial food colors and flavorings and free of salicylates (aspirin-like chemicals that occur naturally in many foods).

A dispute has raged since over this theory. But two recent studies concluded that some children are indeed harmed by food dyes. The author of one, Dr. James Swanson of the University of California at Irvine and the Hospital for Sick Children in Toronto, said the findings suggest that "a subgroup of hyperactive children react to food dyes as if they were toxic drugs."

Five years ago the Nutrition Fondation, which gets just over half its support from the food, drug and chemical industries, named a 14-member National Advisory Committee on Hyperkinesis and Food Additives, co-chaired by Drs. Morris Lipton of the University of North Carolina and Esther Wender of the University of Utah.

That committee reviewed seven studies in all, and concluded that:

Any evidence suggesting that the Feingold diet helps some children is at best "equivocal" or uncertain, and studies of 190 children have produced "no instances of consistent, dramatic deterioration in behavior" when hyperactive children were at first fed a diet without artificial colorings and were then fed the colorings.

The total evidence suggests that children who seem to benefit from the diet are actually having only "a placebo response," a psychological effect that has nothing to do with what they eat or don't eat.

"The evidence now [is that] diet probably has nothing to do" with causing hyperactivity, said Wender. "If it's there" as a cause, it may be producing "one per cent or less" of all hyperactivity, but "I don't believe it's there," said Lipton.

But, said Dr. Bernard Weiss of the University of Rochester, both his study and Swanson's found that dyes profoundly affected some hyperactive children --, two out of 22 in his observations and 17 out of 20 fed a larger dose of food dye in Swanson's. Other work, Weiss said, shows that food dye has its main effect on "the youngest children, pre-schoolers or even younger."

One member of the Nutrition Foundation committee, Dr. Ellen Silbergeld of the National Institutes of Health, said her own tests indicate that Red No. 3, one of the most commonly used food dyes, causes changes in brain chemistry in rats.

The whole issue of the effect of artificial flavors, preservatives and other additives "has still not been studied," she said, under really "stringent," scientifically valid conditions.