A fifth of American adults have read an electronic version of a book in the last year, a trend that is fueling a renewed love of reading, according to a new survey.

The portion of e-book readers among all American adults has increased to 21 percent from 17 percent between December and February, due in large part to a boom in tablet and e-reader sales this past holiday season.

All those devices are turning some consumers into super readers, according to a survey released Thursday by the Pew Internet and American Life Project. E-book readers plowed through an average of 24 titles in the past year, compared with an average of 15 for readers of physical books.

“Those who have taken the plunge into reading e-books stand out in almost every way from other kinds of readers . . . They are avid readers of books in all formats,” said Lee Rainie, director of research at Pew.

Curiously, e-reading somehow sparks a love of books in any format. Even as e-readers are downloading books on computers, tablets and smartphones, they are also checking out more books at libraries and buying more at bookstores and online. About nine in 10 e-book readers said they have also read printed books in the past year, Pew reported in its survey of about 3,000 people 16 and older.

The findings should cheer publishers and educators who hope the convenience of reading and downloading books on devices might lead to fatter bottom lines for the book business as well as greater literacy. E-book fans tend to be affluent and educated, the survey said.

But the news isn’t all good for publishers, according to experts. Even though 40 percent of e-book readers say they are plowing through more book titles on their devices, the industry hasn’t quite turned that trend into fatter profits.

Publishers complain of rampant downloading of pirated books. They add that e-book ­prices are lower — and there is much wrangling with online stores such as Amazon.com and iTunes over fees.

Major publishers are being investigated by the Federal Trade Commission for allegedly colluding with Apple on e-book prices. The alleged price-fixing stems from publishers’ desire to price books higher than Amazon’s stubbornly low rate of $9.99 per book through its Kindle devices.

“This is a different channel for them, and it takes a little more understanding on how to market things,” said Carl Howe, head of consumer tech research at the Yankee Group.

The relatively cheap price of devices has educators looking to tablets and e-readers as educational solutions. Last week Education Secretary Arne Duncan and Federal Communications Commission Chairman Julius Genachowski announced initiatives with tablet makers Samsung and Apple to get textbooks onto devices and into classrooms.