Men who eat a lot of saturated fat could be damaging their sperm, new research suggests. Even more reason every man should go vegan.

Experts at Harvard Medical School in the US found men who consume lots of saturated fat and monounsaturated fat may have fewer sperm. Diets including meat and cheese are especially high in these fats.

In contrast, those who eat healthier fats – specifically omega 3 and omega 6 found in nuts and seeds like cashew and flax – may have healthier sperm that is more active, the study suggests.