Eating bacon could lower male fertility according to the headline reports of a Harvard University study. But there may not be enough clear-cut evidence nor medical logic to persuade meat lovers to change their ways.

The study, reported in the UK newspaper The Telegraph, is the work of Dr Myriam Afeiche of the Harvard School of Public Health. Although based in the Department of Nutrition, she’s worked on several studies on how different factors (including body mass index, TV watching and physical activity) could affect fertility in both men and women.

The latest study involved looking at 156 men who were in couples suffering fertility problems. It looked at their diet, along with the size and shape of their sperm.

It found the amount of ‘normal’ sperm was significantly lower among the men who regularly ate processed meat. Although this included mince, burgers and sausages, bacon is getting the attention because the daily quantity of processed meat that appeared to make a difference was so small that “less than a rasher of bacon” is the easiest point of comparison.

The study also noted that men who ate white fish at least every other day had a higher quantity of healthy sperm.

Bacon afficionados will welcome the many caveats that accompany the survey. Afeiche said there’s no known explanation for why processed meat might have an effect. It’s also worth remembering that the sample group was far from a random selection of the male population, so the fact that all the men were in couples having trouble conceiving may make it much harder to isolate specific causes.

The Telegraph quoted a British fertility expert as saying that measuring the size and shape of sperm can be difficult. He added although there’s clear evidence that healthy food can boost health sperm counts, it’s not yet clear that unhealthy food can specifically cause or exacerbate fertility problems.