A new study has revealed that junk food can make healthy young men infertile by damaging their sperm.
And "trans fats" -- processed oils used to improve food taste cheaply -- are among the worst culprits, the Sun reported.
Fertility doctors from America's Harvard University and the University of Murcia, Spain, analysed sperm from hundreds of men aged between 18 and 22.
They found those who ate a high proportion of junk food -- takeaways, fried foods, processed red meats, crisps, biscuits and cakes -- had poorer quality sperm than those on a nutritious daily diet.
Their sperm was found less likely to survive the journey to fertilise an egg, even if the lads were a healthy weight and exercised.
And those whose diet included the highest level of trans fats -- listed on labels as "hydrogenated oil" and found naturally in many fried foods -- had the worst quality sperm.
According to the results a diet of wholegrain with lots of vegetables and fish produced the best quality.