UnitedHealth Group Inc posted better-than-expected second-quarter profit on Tuesday, helped by growth in the health insurer's plans for seniors and low-income Americans.

The largest U.S. health insurer by market value also raised the low end of its 2009 earnings forecast.

Net income rose to $859 million, or 73 cents per share, from $337 million, or 27 cents per share, a year earlier, when the company took a big charge for a legal settlement.

Analysts on average expected 70 cents, according to Reuters Estimates.

(Reporting by Lewis Krauskopf; Editing by Lisa Von Ahn)