Just one piece of bacon a day can damage a man's fertility, but eating a portion of white fish like halibut or cod every other day can improve it.

A new study from Harvard University took a look at 156 men and kept records of their diets and sperm counts. It found men who regularly ate processed meat had significantly reduced counts, compared to men who ate less bacon, hamburgers, sausages and ham.

But men who ate more white fish had higher counts and healthier sperm.

Fertility experts say they already knew that healthy diets improve male fertility, but this is one of the first studies into specific foods.

--Rob Archer