SAN DIEGO — Testosterone therapy for older men possibly could provide some benefit, but there are also signs it could cause harm, according to a major series of studies published today.

The five studies are published in the Journal of the American Medical Association and JAMA Internal Medicine. Four are the product of the Testosterone Trials, which examined the effect of testosterone gel on healthy men aged 65 and older who had age-related low testosterone levels.

The four 12-month, placebo-controlled studies won’t resolve the long-standing medical debate over the usefulness of testosterone replacement therapy.

It has been marketed as a simple fix for low energy levels and loss of libido, along with health-protective benefits.

But previous studies have repeatedly failed to find rigorous proof of these claims, despite the vigorous advertisements aimed at convincing middle-aged and older men that they need testosterone to combat “Low T.”

Likewise, the new trials provide scant support for testosterone therapy unless low testosterone is disease-related, according to two editorials published along with the studies.