HealthCentral Network has acquired fast-growing Web health community Wellsphere which would boost the size of its online audience from 6 million monthly unique visitors to 10 million.

The San Mateo tech company Wellsphere was started in 2007 by a group of Stanford University Business School graduates, including CEO Ron Gutman. It offers health management technology that includes a mobile alert system for health-related text messages and reminders, and software that deciphers specific health information to help people make personal health decisions.

"This deal combines HealthCentral's business savvy with Wellsphere's technical expertise, and will allow us to build on our current success on a broader scale," Gutman said.

Wellsphere much like Google, features a central search box on its home page that allows users to search for information on specific health-related subjects. The WellPages combine articles, blogs, a Q&A section, and videos on the topic queried from sources ranging from the FDA to health and fitness magazines.

Arlington, Va.-based HealthCentral with the acquisition stands to gain more clout to compete with larger competitors and CEO Chris Schroeder stressed that the merger is as much about synergy as increasing size. He said Wellsphere's focus on wellness and healthy living topics will complement HealthCentral's health condition-oriented portal. "This is a significant combination of quality audience and content with one-of-a-kind technology and scale," said Schroeder.

The deals details and financial aspects were not disclosed though according to Schroeder HealthCentral will incorporate Wellsphere's technical expertise, while the startup will benefit from HealthCentral's more established business and ad sales operation. The companies will maintain separate Web sites as well as separate offices on both coasts and the company's executive team will join the HealthCentral team in Arlington, Va., near Washington, D. C.

HealthCentral has made three acquisitions in the last seven months, including MedTrackAlert, TheBody. com and Wellsphere. According to the comScore rankings despite HealthCentral's acquisition of Wellsphere it would not lift them into the top ten health sites.

Last fall, Everyday Health Network owned by the Waterfront Media- merged with Revolution Health Network to overtake WebMD as the largest online health property, with
26.7 million unique visitors in December 2008. Schroeder indicated that HealthCentral and Wellsphere had higher-quality audiences than rivals because they have not relied on search engine marketing to drive traffic growth.

"Because our traffic is organic... our audience members arrive more engaged, ready to act, and research shows they do act on what they learn," he said. "We now will be able to deliver measurably better ROI for advertisers on an even larger scale."