14 March 2012 Last updated at 03:39 ET
A diet high in saturated fat has been linked with a reduced sperm count.
A study of 99 men attending a US fertility clinic found those eating junk food diets had poorer sperm quality.
High intakes of omega-3 fatty acids, found in fish and plant oils, were associated with higher sperm concentration.
More work is needed to confirm the findings, the researchers report in the journal Human Reproduction.
The team, led by Prof Jill Attaman from Harvard Medical School in Boston, questioned men about their diet and analysed sperm samples over the course of four years.
Compared with those eating the least fat, men with the highest fat intake had a 43% lower sperm count and 38% lower sperm concentration (number of sperm per unit volume of semen).
..it does add weight to the argument that having a good healthy diet may benefit male fertility as well as being good general health advice.
Men consuming the most omega-3 fatty acids had sperm with a more normal structure than men with the lowest intake.
Prof Attaman said: "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."
Follow this link:
Diet 'linked' to low sperm counts
