Royal Numico NV, Europe's top baby food maker, said today that it is buying General Nutrition Cos. for $2.5 billion, a deal that would create the world's biggest nutrition company.

The $25-a-share offer for the world's biggest maker of vitamin and mineral supplements is a 9 percent premium over GNC's closing price on Friday. Numico is offering $1.77 billion for all outstanding GNC shares and would assume $760 million in debt.

The purchase would give Numico access to the biggest distribution network for nutritional products in the United States, where 45 percent of adults take vitamins and the market for supplements is expected to nearly double to $16.6 billion by 2003. It would be the largest takeover for Numico and for the U.S. nutrition business.

"This is a mega-deal," said Roel Gooskens, an analyst at HSBC Securities in Amsterdam. "It will make Numico a global player and the world's leader in nutraceuticals, with baby food activities on the side."

The purchase would immediately contribute to earnings per share and speed company growth, Numico said.

Gooskens, who rates Numico shares a "buy" and raised his price target to 50-plus euros after the takeover was announced, said he sees GNC adding an annualized 10 percent to 25 percent to earnings.

"I think the market will react very enthusiastically tomorrow," Gooskens said.

The acquisition of Pittsburgh-based GNC would nearly double Numico's sales to about $3 billion, from $1.6 billion last year, and would have added $91 million in net income last year to Numico's $157 million.

Sales of $1.42 billion last year gave GNC 13 percent of the U.S. market for supplements. Combining GNC's marketing and branding experience with Numico's research is expected to bring a 10 percent increase in sales by 2002.

Numico, which already is active in 40 countries from Europe to Asia, will be enhanced by GNC's 4,203 own stores in all 50 states and 25 foreign markets. In addition, GNC has allied with Rite Aid drugstores and drugstore.com, which sells health products via the Internet.

The Dutch company is eager to tap GNC's knowledge of mass-market retailing, in particular drugstore sales, which is becoming increasingly important to nutrition sales. And GNC would benefit from Numico's research and development programs to help fend off encroachment by pharmaceutical companies.

"This merger creates the largest company in the world exclusively devoted to human nutrition," Numico chief executive Hans van der Wielen and GNC chief executive William Watts said in a joint statement. "Proprietary research, coupled with marketing and branding expertise, will determine category leadership."

Watts is expected to be named to Numico's management board after the purchase is completed. Other senior GNC executives agreed to stay on at Numico.

GNC's directors unanimously approved the offer and recommended that shareholders accept it. Numico plans to begin the tender offer by July 12. The takeover will be subject to regulatory approval.

Numico plans to finance the takeover by selling 1.05 billion euros ($1.07 billion) in new shares and subordinated convertible bonds. A bridge loan has been secured from ABN Amro Holding NV and JP Morgan & Co., which is advising Numico on the takeover. GNC is being advised by Morgan Stanley Dean Witter & Co.

Numico shares, which closed before the announcement, ended at 34.4 euros, a gain of 0.30 euro or 0.88 percent. GNC shares closed Friday at $22.87 1/2 -- up 37 1/2 cents, or 1.7 percent. The shares did not trade today because of the Independence Day holiday.

CAPTION: GNC Acquisition (This chart was not available)