| | |  Health & Beauty | July 2008 
Obese Men Have Less Semen, More Sperm Abnormalities
 Mary Rice - European Society for Human Reproduction and Embryology
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Obese men should consider losing weight if they want to have children, a scientist told the 24th annual conference of the European Society of Human Reproduction and Embryology today (Wednesday 9 July). Dr. A Ghiyath Shayeb, from the University of Aberdeen, Aberdeen, UK, said that his research had shown that men with a higher body mass index (BMI) had lower volumes of seminal fluid and a higher proportion of abnormal sperm.
Dr. Shayeb and colleagues looked at the results of seminal fluid analysis in 5316 men attending Aberdeen Fertility Centre with their partners for difficulties in conceiving. 2037 of these men had complete data on their BMIs. "We felt that it was possible that male overweight might contribute to fertility problems," he said, "particularly since it is a known risk factor for problems in conceiving among women."
The scientists divided the men into four groups according to their BMI, from being underweight to being considerably overweight. Taking into account other characteristics that could confound the analysis, such as smoking, alcohol intake, age, social deprivation, and the length of time of abstinence from sex prior to producing a semen sample for analysis, they looked for a relationship between BMI and semen quality. The analysis showed that the men in Group B, who had an optimal BMI (20-25, as classified by WHO), had higher levels of normal sperm than those in the other groups. They also had higher semen volume. There was no significant difference between the four BMI groups in sperm concentration or motility.
The researchers did not look at DNA damage in the sperm, preferring to look at the parameters of the routine semen analysis, which all men attending the fertility centre will have at least once. "Other studies have suggested an association between male obesity and increased DNA damage in the sperm, which can be associated with reduced fertility as well," said Dr. Shayeb.
"Our findings were quite independent of any other factors," he said, "and seem to suggest that men who are trying for a baby with their partners, should first try to achieve an ideal body weight. This is in addition to the benefit of a healthy BMI for their general well being.
"Adopting a healthy lifestyle, a balanced diet, and regular exercise will, in the vast majority of cases, lead to a normal BMI. We are pleased to be able to add improved semen quality to the long list of benefits that we know are the result of an optimal body weight."
The team intends to follow up their research by comparing male BMI in fertile and infertile couples to see if the poorer semen quality correlates with reduced fertility. "There has been a significant rise in the numbers of men with poorer semen parameters in the industrialised world," said Dr. Shayeb, "but this has not been reflected so far in male infertility. To compare male BMI in these two groups therefore seemed to us to be a logical next step."
Further research is also needed on exactly how obesity affects semen production, said Dr. Shayeb. "The mechanism for the relationship could be a number of things – different hormone levels in obese men, simple overheating of the testicles caused by excessive fat in the area, or that the lifestyle and diet that leads to obesity could also lead to poorer semen quality. We just don't know the answer yet, but this is an important question that needs urgent attention."
Diabetes Linked to Male Infertility
Mary Rice - European Society for Human Reproduction and Embryology
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Barcelona, Spain: Diabetes in men has a direct effect on fertility, a scientist told the 24th annual conference of the European Society of Human Reproduction and Embryology today (Wednesday 9 July). Dr. Con Mallidis from Queen's University, Belfast, UK, said that, despite the prevailing view that it had little effect on male reproductive function, the Belfast group had shown that diabetes caused DNA damage in sperm.
The increase in the numbers of diabetics diagnosed at a young age has coincided with worldwide concerns over male fertility, he told the conference. "But this is not simply a coincidence," he said. "We have shown for the first time that diabetes adversely influences male fertility at a molecular level."
The scientists studied semen samples from men with diabetes who were receiving insulin therapy. On initial routine microscopic examination the semen samples appeared normal, apart from a slight decrease in volume.
"But when we looked for DNA damage, we saw a very different picture," said Dr. Mallidis, adding that this is not part of a routine semen analysis. "Sperm RNA was significantly altered, and many of the changes we observed are in RNA transcripts involved in DNA repair. And comparison with a database of men of proven fertility confirmed our findings. Diabetics have a significant decrease in their ability to repair sperm DNA, and once this is damaged it cannot be restored."
Transcription is the synthesis of RNA under the direction of DNA, and is the first step towards gene expression, where the information from the gene becomes a product such as a protein translating the genetic information into a cellular function. If there are errors in transcription, there will also be errors in the function of the gene. "We were particularly interested to see a fourteen-fold decrease in the expression of a protein called ornithine decarboxylase, which is responsible for the production of spermine and spermidine, compounds responsible for cell growth that help stabilise the structure of DNA. We also found that spermatogenesis 20, a factor unique to the testis and whose function remains unknown, was greatly increased. Taken together, these factors indicate clearly that having diabetes has a direct influence on the health of semen."
Sperm DNA quality is known to be associated with decreased embryo quality, low embryo implantation rates, higher miscarriage rates, and some serious childhood diseases, in particular some childhood cancers. Over the years possible causes for sperm DNA fragmentation have been suggested but to date the exact mechanism for the damage remains unknown, say the scientists.
"We found a class of compounds known as advanced glycation end products (AGEs) in the male reproductive tract. These are formed as the result of glycation (the addition of sugar)," said Dr. Mallidis, "and accumulate during normal ageing. They are dependent on life style – diet, smoking etc – and in many diabetic complications are centrally implicated in DNA damage. We believe that they play a similar role in the male reproductive system."
The scientists intend to follow up their work by trying to determine how AGEs cause and contribute to DNA damage. They believe that they may have uncovered a new role for AGEs, and that their influence goes far beyond diabetes and its complications.
"We must now try to develop strategies to protect sperm, and to diminish the accumulation of AGEs," said Dr. Mallidis. Such strategies could involve changes in diet, disrupting a step in the formation of AGEs, or increasing the body's protection against AGEs, possibly through the use of dietary supplements.
"Finally, there is spermatogenesis 20. What does it do, how does it do it, under what circumstances and why? Why is it so greatly increased in diabetics? We need to find answers to all these questions," said Dr. Mallidis. |
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