Despite the unclear picture regarding the causes of male infertility, unproven solutions are sold on social media.

Naturopath Lucas is one of the health influencers whose content includes warnings about fertility rates.

“We are seeing a global epidemic, a decline in fertility across the board,” he tells the BBC.

But Lucas’ concern comes with some misleading claims: for example, he told his YouTube audience that men would be infertile in 33 years, which is not supported by scientific evidence.

He sells online courses, offers personalized training, and sells supplements for men looking to increase testosterone and fertility.

Her social media content, which promotes some unproven fertility protocols, has gone viral.

“I recommend men apply an ice pack against their underwear, two or three times a day for about 10 to 15 minutes,” he says, stating that clients have told him their partners became pregnant after trying this.

“This is more preliminary. I think it’s a viable enough strategy to try,” he says.

When asked about the unproven nature of his advice, Lucas said he believed icing the testicles was a “promising intervention,” but added that he would like to see more research.

NHS guidance on low sperm count , externalHe says tight underwear can increase the temperature of your testicles, which can affect the quality of your sperm.

Lucas also advises his followers and clients on healthy eating, sleep and exercise, steps that have a strong evidence base.

Professor Jayasena recommends lifestyle changes to improve fertility.

“If there are reversible things like [quitting] smoke, like [losing] weight and increasing physical activity,” he says, “is by far the best thing to do.