Men who dream of one day becoming a father take note: a new study suggests that consuming a high-fat diet reduces sperm count and quality.

On the bright side, consuming more omega-3 polyunsaturated fats, such as those found in fish and plant oils, is associated with sperm that is better formed, according to the findings.

The researchers caution that the study is small -- it included only 99 men from the United States -- and its findings must be replicated in other research to confirm the link between fats and sperm quality.

Lead researcher Jill Attaman, who was a clinical and research fellow in reproductive endocrinology and infertility at Massachusetts General Hospital and an instructor at Harvard Medical School at the time of the study, said men should still heed the warning the study sounds to improve both their reproductive and overall health.

"In the meantime, if men make changes to their diets so as to reduce the amount of saturated fat they eat and increase their omega-3 intake, then this may not only improve their general health, but could improve their reproductive health too," Attaman said in a statement, noting that foods that are high in saturated fats are a known risk factor for a range of cardiovascular diseases.

The findings are published in the medical journal Human Reproduction.

While previous research has investigated the link between body mass index and semen quality, and produced mixed results, Attaman and her colleagues sought to probe the lesser-studied question of whether dietary fats have an impact on semen quality.

Between December 2006 and August 2010, they asked 99 men who were attending the Massachusetts General Hospital fertility clinic about their diets and also analyzed samples of their semen. They then divided the men into three groups according to how much fat they consumed.

The third who consumed the most fat had a 43 per cent lower sperm count and 38 per cent lower sperm concentration than the men in the group that consumed the least amount of fat. (Sperm count is defined as the total number of sperm in the sample, while sperm concentration is the number of sperm per millilitre.)

The researchers found saturated fats to have the biggest impact on semen quality. The men who consumed the most saturated fats also had a sperm concentration 38 per cent lower than men who ate the least.

"The magnitude of the association is quite dramatic and provides further support for the health efforts to limit consumption of saturated fat," Attaman said.

While the researchers concede that 71 per cent of men in the study were overweight or obese, which has been linked in previous research to lower sperm counts, they used a statistical model to isolate the effects of fat intake on semen quality.

In addition to the small number of study subjects, the researchers admit other limitations, including that food questionnaires are not the most accurate way to determine everything the men ate. Also, they only collected one sperm sample from each man.