Everyone knows saturated fat is bad in high amounts -- it might even kill you.
A new study suggests that fat may also damage semen quality among men.
A preliminary study published online in the medical journal Human Reproduction, suggests that men who intake higher amounts of omega-3 polyunsaturated fats, like the ones found in fish and plant oils, have better-formed sperm than those who don't.
A research team, led by Dr. Jill Attaman conducted the study, a small trial involving 99 men in the U.S. over the course of four years.
Attaman was a clinical and research fellow in reproductive endocrinology and infertility at Massachusetts General Hospital and an instructor in obstetrics, gynecology and reproductive biology at Harvard Medical School during the study.
The men were asked about their diets and then separated into three groups according to the amount of fat they consumed.
Those in the highest-fat-consumption had a 43 percent lower total sperm count and 38 percent lower concentration of sperm than the men in the group who ate the least amount of fat.
Attaman suggests that the benefits of lowering the amount of fat in a man's diet extend beyond heart health.
A lower-fat diet "may not only improve their general health, but could improve their reproductive health too," she said in a statement.
One fertility specialist cautioned against relying on the findings of a study that relies on the past history of participants to diagnose their current condition.
Dr. Vicken Sahakian of the LA-based Pacific Fertility Center, said the "retrospective" nature of the study limits its usefulness. It would have had greater value if the men had been put on very strict diets and compared with a control group, he said.
In addition, Sahakian questioned the focus of the study.
"Fertility has to be correlated to pregnancy rates, not sperm counts," Sahakian said.
Attaman's research team also measured the levels of fatty acids in the sperm and seminal plasma of 23 participants. It found that levels of saturated fatty acids were also negatively related to sperm concentration.
The research team emphasized that these findings were preliminary and it would have to conduct more studies with larger samples to confirm them.