99(A) 4

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                                                                    July 9, 1999

                       GENERAL NUTRITION COMPANIES, INC.
                                300 SIXTH AVENUE
                              PITTSBURGH, PA 15222

To the Stockholders of General Nutrition Companies, Inc.:

    I am pleased to report that on July 5, 1999, General Nutrition Companies,
Inc. (the "Company") entered into an Agreement and Plan of Merger (the "Merger
Agreement") with Koninklijke Numico N.V., a company incorporated under the laws
of The Netherlands ("Numico"), and Numico Investment Corp., a Delaware
corporation and an indirect wholly owned subsidiary of Numico (the "Purchaser").
The Merger Agreement provides for the acquisition of all outstanding shares of
Common Stock, par value $0.01 per share, of the Company (the "Common Stock") by
the Purchaser at a price of $25.00 per share, net to the seller in cash, without
interest. Under the terms of the proposed transaction, the Purchaser has
commenced a tender offer (the "Offer") for all of the outstanding shares of
Common Stock at $25.00 per share, net to the seller in cash, without interest.
The Offer is currently scheduled to expire at 12:00 Midnight, New York City
time, on Thursday, August 5, 1999, unless otherwise extended.

    Following the successful completion of the Offer and upon approval by a
stockholder vote, if required, the Purchaser will be merged with and into the
Company (the "Merger") and all shares of Common Stock not purchased in the Offer
will be converted into the right to receive, without interest, an amount in cash
equal to the amount paid pursuant to the Offer.

    YOUR BOARD OF DIRECTORS HAS UNANIMOUSLY APPROVED THE MERGER AGREEMENT, THE
OFFER AND THE MERGER, DETERMINED THAT THE OFFER AND THE MERGER ARE FAIR TO, AND
IN THE BEST INTERESTS OF, THE HOLDERS OF SHARES OF COMMON STOCK AND RECOMMENDS
THAT ALL HOLDERS OF SHARES OF COMMON STOCK TENDER THEIR SHARES OF COMMON STOCK
PURSUANT TO THE OFFER.

    Accompanying this letter is a copy of the Company's
Solicitation/Recommendation Statement on Schedule 14D-9 and the Company's
Information Statement pursuant to Section 14(f) of the Securities Exchange Act
of 1934, as amended, each filed by the Company with the Securities and Exchange
Commission. The Board of Directors of the Company has received an opinion, dated
July 3, 1999, of Morgan Stanley & Co. Incorporated, financial advisor to the
Company, that the $25.00 per share cash consideration to be paid in the Offer
and the Merger to the holders of shares of Common Stock is fair, from a
financial point of view, to such holders. A copy of this opinion is attached to
the Schedule 14D-9.

    Also accompanying this letter is a copy of the Offer to Purchase and related
materials of Numico and the Purchaser, including a Letter of Transmittal for use
in tendering your shares of Common Stock. These documents set forth the terms
and conditions of the Offer and provide instructions for tendering your shares
of Common Stock.

    WE URGE YOU TO READ EACH OF THE ENCLOSED MATERIALS CAREFULLY.

    The management and directors of the Company thank you for the support you
have given the Company.

                                          Sincerely,

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                                          William E. Watts
                                          PRESIDENT AND CHIEF EXECUTIVE OFFICER