General Nutrition Centers Inc. posted a $13.3 million profit in the first quarter, an improvement over the same quarter last year when acquisition-related costs helped produce a $50.5 million loss.

The Pittsburgh vitamin retailer said total revenues in the three months ended March 31 rose 9.2 percent to $428.1 million versus $391.9 million last year. Revenues rose across the company's business segments, which include its company-owned stores, franchise locations and a manufacturing/wholesale operation.

Sales in U.S. corporate stores that have been open at least a year rose 2.2 percent, a number that includes sales from the Internet. Same-store sales at Canadian corporate stores rose 2.6 percent.

GNC was acquired in March 2007 by private equity investors, a transaction that layered more than $50 million in expenses into that quarter's results.