Exact age men's sperm 'declines' and why you should be wary

It's no secret that as you get older, some parts of your body don't work as well as they used to - and men's sperm is no different.

New scientific research has revealed the exact age when sperm quality starts to decline and mutations - or changes in DNA - begin to develop.

Published earlier this month in the journal Nature, the landmark study was conducted by researchers from the Wellcome Sanger Institute, in collaboration with the TwinsUK study at King’s College London.

It confirmed that these so-called 'mutations' accumulate along with age. So essentially, the older men get, the more subpar their semen becomes.

UK-based researchers tracked the sperm samples belonging to 81 men, who are between the ages of 24 and 75.

They used a highly accurate duplex sequencing technique called NanoSeq to conduct the study and detect the mutations.

New research has revealed that sperm mutations are more common the older men get (Getty Stock Image)

The testing found that around one in 50 of the men in their early thirties' sperm had disease-causing mutations. However, this rose to almost one in 20 between the ages of 43 and 70.

The experts have labelled the research as 'important' and highlighted that older fathers have a 'higher risk of passing on more pathogenic mutations'.

The team also claimed to identify over 40 different genes that can cause sperm stem cells to mutate, which is a genetic phenomenon known as 'selfish sperm', as per The New York Post.

Science Alert explains that many of these mutations have previously been linked to developmental disorders and cancers.

The publication explains that these mutations occur in DNA when cells replicate, and arise either by random chance or because of environmental stresses.

Geneticist Matthew Neville, from the Wellcome Sanger Institute, said: "We expected to find some evidence of selection shaping mutations in sperm.

"What surprised us was just how much it drives up the number of sperm carrying mutations linked to serious diseases."

Mutations occur in DNA when cells replicate (Getty Stock Image)

While Professor Matt Hurles, Director of the Wellcome Sanger Institute and co-author of the study, added: "Our findings reveal a hidden genetic risk that increases with paternal age.

"Some changes in DNA not only survive but thrive within the testes, meaning that fathers who conceive later in life may unknowingly have a higher risk of passing on a harmful mutation to their children."

The researchers wrote in the study: "These findings shed light on germline selection dynamics and highlight a broader increased disease risk for children born to fathers of advanced age than previously appreciated."

The study measured the amount of sperm carrying these harmful mutations and reported these age-related increases:

• 26 – 42 years: Approximately 2% of sperm carried disease-causing mutations
• 43 – 58 years and 59 - 74 years: This proportion rises to between 3% and 5%
• 70: The percentage of sperm carrying disease-causing mutations was approximately 4.5%