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Obese men in their 60s have lower sperm counts than slimmer individuals in the same age group, a study suggests.
Scientists led by Utah University looked at 44,000 testes cells involved in the production of sperm from eight men aged between 60 and 72 years, and four men in their early 20s.
Those from older men who were a healthy weight showed only ‘weak’ reductions in their ability to make sperm compared to those from younger men.
But those from obese individuals showed a ‘very limited’ ability to keep producing the male sex cells.
Scientists did not suggest why obese older men had a lower sperm count, although previous studies have suggested it may be because of lower testosterone levels or warmer testicles.
Scientists led by Utah University found obese men in their 60s had reduced sperm counts compared to those in the age group who were a healthy weight
About two in five Americans — or 138million people — are obese, estimates from the Centers for Disease Control and Prevention suggest.
Sperm counts do generally decline in age, peaking when a man turns 17 and remaining high until their 40s.
But levels among men have been plunging overall since the 1970s, studies in Europe, North America and Australia show.
It is not clear what’s triggering the decline, but scientists have suggested bigger waistlines, poor diets and even exposure to pollution could be behind it.
In the study — published today in the journal Developmental Cell — scientists used an autopsy to obtain the testicle cells.
They then looked at the cells RNA for age-related changes, to determine how good they were at manufacturing sperm.
Among the participants above 60 years old, five had a Body Mass Index’s (BMIs) below 27, putting them in the overweight and healthy range.
Three had a BMI above 30, putting them in the obese category.
All of them had children, showing fertility in their younger years.
In the group of younger men, aged 17 and 22 years, there were individuals who were both a healthy weight and obese.
Results showed those in the younger age group had ‘normal and complete’ sperm production irrespective of their BMI measurements.
But in older groups, it said this dropped if someone had a higher BMI.
Dr Bradley Cairns, the chair of the Department of Oncological Sciences at Utah University who led the study, said: ‘Pronounced dysregulation [is] caused when aging is combined with additional factors such as obesity.
‘Aging may confer a combination of modest molecular changes that sensitize the testis for additional dysregulation.’
Previous studies have linked a higher weight to a lower testosterone level, which they suggest could then reduce sperm counts.
There are also suggestions obese people have warmer testicles due to more fat cells, which could hamper sperm production.
Sperm are produced at around 93F (34C), which is slightly below the human body temperature of 98.6F (37C).
Scientists said they could not determine whether the changes to sperm production in obese older men were unique or due to accelerated aging.
Studies involving more individuals are needed to confirm the findings.
Source: Daily Mail
