According to new research from The University of Texas Health Science Center at Houston, men who drink the caffeine equivalent of two to three cups of coffee per day are less likely to have erectile dysfunction .

The study, which was published in the journal PLOS ONE , found that men who consumed between 85 and 170 milligrams of caffeine a day were 42 percent less likely to suffer from ED, while those who consumed between 171 and 303 milligrams were 39 percent less likely.

The researchers surveyed 3,700 men, all of whom were asked to fill out a questionnaire about how much caffeine they had consumed over the past 24 hours. While the study found that caffeine intake reduced the likelihood of ED in obese, overweight and hypertensive men , the same was not true of those with diabetes.

Caffeine could not overcome the detrimental effects of diabetes on erectile dysfunction," lead study author David Lopez explained. "We were not very surprised by this, because diabetes is one of the strongest risk factors associated with erectile dysfunction ."

An estimated 30 million American men struggle with ED , which is the inability to sustain an erection for as long as desired. Overall, the risk of erectile dysfunction increases with age. About 40 percent of 40-year-olds struggle with ED and 70 percent of 70-year-olds have the same problem, as previously reported by The Huffington Post.

The researchers theorized that caffeine's effect on the body includes relaxing the helicine arteries of the penis, which in turn improves blood flow, which is how erections are formed:

Graphic by Alissa Scheller for The Huffington Post.

Caffeine sources on the survey included energy drinks and soda in addition to coffee and tea, but Lopez pointed out that soda and energy drinks are extremely unhealthy.

"Keep in mind that besides caffeine, energy drinks and soda have other ingredients that we dont know too much about," he told HuffPost. "We do know a lot about sugar -- its strongly linked with diabetes and obesity . There are other drinks that are sugar-free, but some of those ingredients are associated with cancer."

Because this is an association study, Lopez says he can't make any recommendations for caffeine intake just yet.

"I can tell you that a foundation has been laid for the association between caffeine and erectile dysfunction," he said. "This is a good start, I can tell you that."

For now, we'll just add it to our long list of reasons to drink coffee -- as if we needed another one.

For more info on how to address problems with ED, read this previous HuffPost report .