NEW YORK - Men who eat healthier diets may also have healthier sperm, new research from Spain shows.

A healthy, well-balanced diet is not just important for preventing diseases like diabetes, high cholesterol, or hypertension, but it may be useful for preserving or improving your reproductive health too, Dr. Jaime Mendiola of the University of Murcia, the lead researcher on the study, told Reuters Health via e-mail.

A number of studies have suggested that there are links between consuming certain nutrients and male infertility, Mendiola and his team note in the journal Fertility and Sterility. They had previously investigated the relationship between consumption of certain foods and semen quality, and found that men who ate more dairy products and more meat, and less lettuce, tomatoes, and fruit, were more likely to have poor semen quality.

That investigation didn't look at specific nutrients. But in this one, Mendiola and his team compared the nutrient content of the diets of 30 men with poor semen quality and 31 men with normal sperm. All were attending fertility clinics.

The men with poor semen quality had low sperm counts and relatively high percentages of abnormally formed sperm. All of the men provided at least two semen samples.

After controlling for cigarette smoking, age, body mass index, and exposure to toxic chemicals in the workplace, the researchers found that diet remained an important factor. The men with normal semen ate more carbohydrates, fiber, folate, vitamin C and lycopene than the men with poor semen quality. The men with healthy semen also ate less fat and less protein.

Low levels of antioxidant nutrients in the diet seem to have a negative effect on semen quality, Mendiola and his team write.

A healthy diet does seem to be a factor in sperm quality, the researcher concluded, but he added that randomized controlled trials will be needed to confirm the relationship.

SOURCE: Fertility and Sterility, May, 2009.