Online porn is damaging men's sexual health, a leading NHS doctor has said.

In a Newsbeat documentary broadcasted on the BBC, psychosexual therapist Angela Gregory explained that more and more men in their early adulthood were suffering from erectile problems. Asked what she thought the reason for this was, the health professional blamed addiction to online pornography, because of its potential to distance men from real-life sexuality.

In the last two decades, the unprecedented growth of internet has revolutionised people's access to porn, making it easier to find erotic content online 24/7, everywhere. In some cases, this has had a pernicious effect: a greater number of young men may have developed an addiction to porn.

Some are so used to watching sex videos online, either on their computers or their smartphones, that they struggle to be sexually aroused with their partner(s) or to maintain an erection throughout sexual intercourse.

Men in their twenties can thus suffer from erectile dysfunction – a new phenomenon as the problem has traditionally been associated with older age and to health issues such as diabetes, MS or cardiovascular disease.

"These younger men do not have organic disease, they've already been tested by their GP and everything is fine. So one of the first assessment questions I'd always ask now is about pornography and masturbatory habit because that can be the cause of their issues about maintaining an erection with a partner", Gregory says. These sexual problems can take a toll on young men's relationships.

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However, some disagree with this assessment. According to sexual health charity FPA, the effect that watching porn can have on people's sexual health is complex, and it's too simplistic to just say that porn is harmful.

"Certainly we have anecdotal evidence of men reporting sexual problems, including difficulty getting or keeping an erection, or reaching climax too soon, when they have spent a lot of time watching porn. However, it's not uncommon for younger people to experience sexual problems although we know that many don't seek help, sometimes out of embarrassment. It's really important that health professionals are aware of these issues and aren't too quick to dismiss patients because they are young and assume that experience and confidence will help any problems to naturally disappear in time. Reaching people with problems when they are young and supporting them with treatment and counselling can help prevent problems from become lifelong issues", FPA's Head of Training and Programmes, Paul Casey, told IBTimes UK.

"Young people have increasingly easy access to a whole range of sexually explicit material online, and it is vital they have the knowledge and support to make sense of what they see, and separate out the fantasies portrayed in pornography from the realities of what it means to have sex and be in a relationship. This is one of many important reasons why the government should make sex and relationships education (SRE) statutory in all schools."

This article was updated to include comment from charity FPA. Newsbeat documentary "Brought up on Porn" is available on BBC Iplayer.