Nabisco Holdings Corp., Parsippany, N.J., Monday announced a restructuring program that will include reducing its worldwide workforce of some 54,000 people by about 4,200, a 7.7% cutback. The company also said it plans to divest itself of a number of smaller brands, but did not name them. The company will take a pre-tax charge of $51 million to write-down the value of several non-strategic product lines in anticipation of their sale. The businesses are relatively small, regional brands, which had combined sales in 1995 of $127 million. The company said that the bulk of the savings realized by the cutbacks "will be reinvested to fuel the growth of both its core businesses and new product initiatives."