The study was small, including just 99 men who were divided into three groups based on their overall consumption of fat.
Those with the highest daily fat intake had a 43% lower total sperm count and 385 lower sperm concentration than those with the lowest fat intake, according to the study published online in the journal Human Reproduction.
"Although this study is limited by the number of patients evaluated, I do think it tells us something important in that it reminds us that male fertility is delicate and can be easily influenced by the same things that influence our general health," said Dr. Joseph Alukal, director of male reproductive health at NYU Langone Medical Center and assistant professor at the NYU School of Medicine, New York City.
"It is one more good piece of evidence reminding us that simple health interventions like diet and exercise can be beneficial with regard to improving sperm counts and having a child," added Alukal, who was not involved in the new study.
Total sperm count refers to the total number of sperm in the ejaculate, while sperm concentration is the number of sperm in a certain amount of semen.
The World Health Organization defines normal total sperm count as at least 39 million sperm in the ejaculate and normal sperm concentration as at least 15 million sperm per milliliter of semen.
Saturated fats to blame
Saturated fats appeared to be the major factor linked to semen quality in the study. Men who consumed the most saturated fats had a 35% lower total sperm count and a 38% lower sperm concentration than those who ate the least saturated fat, the researchers found.
Study author Jill Attaman agreed the findings underscore the importance of a healthy diet. "The magnitude of the association is quite dramatic and provides further support for the health efforts to limit consumption of saturated fat given their relation with other health outcomes such as cardiovascular disease," she said in a journal news release.
The study also found that men who consumed the most omega-3 fatty acids (the type found in certain fish oils) had about 2% more sperm that were correctly formed than those with the lowest omega-3 intake.
The researchers noted that 71% of the men in the study were overweight or obese, which is close to the 74% rate among men in the general US population.
Alukal stressed that more research is needed to confirm the findings of this small study. "Certainly more work along these lines looking at increased numbers of patients for a longer period of time would be very useful," he said. The study is also observational in nature, and cannot prove cause-and-effect.
Attaman was a clinical and research fellow in reproductive endocrinology and infertility at Massachusetts General Hospital and an instructor in obstetrics, gynaecology and reproductive biology at Harvard Medical School when she conducted the research. She is currently an assistant professor of obstetrics and gynaecology at Dartmouth Medical School and a reproductive endocrinology and infertility subspecialist at Dartmouth-Hitchcock Medical Center.
The healthy sperm diet
The Academy of Nutrition and Dietetics outlines healthy eating for men.
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