The number of patients taking cholesterol-lowering statin drugs has significantly increased following new cardiology practice guidelines issued last year, but the consensus among experts as to the advisability of such recommendations is split.

Revised guidelines issued in late 2013 by the American Heart Association and the American College of Cardiology have seen an additional 12.8 million Americans advised to use statins to lower their cholesterol levels.

Most of them have been older adults, who were put on a course of statins even though they have shown no symptoms of cardiovascular disease.

While the body needs some cholesterol to function correctly, high levels can see excess cholesterol, also known as lipids, clogging arteries and restricting or even blocking blood flow.

Strokes or heart attacks can be the result.

While exercise and a change in diet can lower cholesterol, when they are ineffective statins are often prescribed.

If the new ACC/AHA guidelines are followed in full, almost half of American age 40 and over may soon be on prescriptions of statins, doctors have noted, almost double the figure currently taking them.

The revised guidelines were based on new analysis of stroke and heart attack statistics that included a more wide-ranging assessment.

Some cardiologists say they are concerned the new guidelines do not take into account the gender of patients, with the result that too many women -- who may face more severe side effects than men do and see fewer benefits from statins -- have been put on statins by their doctors.

Side effects of statins can include development of diabetes, kidney damage, muscle pain and cognitive changes.

Lowering cholesterol in women should not be the end in itself in the absence of any symptoms of heart problems, as cholesterol may not be playing the identical role in such risks for women as in men, says Dr. Rita Redberg, a cardiologist at the University of San Francisco and editor of JAMA Internal Medicine journal.

"You can have high cholesterol and still be really healthy and have a low risk of heart disease," Redberg says.

Some studies suggest statin use does not seem to prevent a first heart attack in healthy women and has not been shown to save lives, she says.

Although women are more than half the U.S total population, in clinical trials of statins they have been often underrepresented, she says.

Not all experts see a problem with the new guidelines, or the fact that data from trials may not fairly represent women.

"The absence of data is not the same as negative data," says Dr. C. Noel Bairey Merz, director of the Barbra Streisand Women's Heart Center at the Cedars-Sinai Heart institute in Los Angeles.