Sperm cells are in danger, and men's health practices may have something to do with it. Last year, a Swedish study published by PLOS Biology showed that a change in diet had an impact on the speed of sperm cells.For almost two weeks, researchers analysed the sperm of 15 healthy, non-smoking men. During the first week, the volunteers were fed a Scandinavian-based diet, and then switched to a diet rich in sugars during the second week, as reported by the scientific journal. ‘Sperm motility can be altered in a short period of time’The results showed that participants with sperm with low motility (ability to move), had similar sperm to the others following the experiment. ‘Sperm motility can be changed in a short period of time and seems to be closely related to diet,’ concluded Anita Öst, lecturer at the Department of Clinical and Experimental Medicine at the University of Linköping.The current study does not yet indicate whether sugar is the cause, but further research is expected to be carried out soon.What to eat?The burning question (poor choice of words). Researchers from the Rovira i Virgili University and the Pere i Virgili Health Research Institute in Tarragona, Spain, explained how to increase sperm quality in Human Reproduction Update.For example, omega-3 fatty acids should be consumed. They can be found in all kinds of fish, such as sardines, mackerel, and salmon. Vitamin D can also be found in fish, which is very important in order to have healthy sperm.You also need to fill up on vitamin C, which can be found in berries and citrus fruits, vitamin E, found in rapeseed and walnut oil, and also beta-carotene, found in carrots and mangoes. Spinach and cabbage will give you the vitamin B9 you need to have healthy sperm. Don't neglect tomatoes either, they contain lycopene, a vitamin that is good for your little swimmers.Which foods to avoid?On the other hand, if you want to have quality sperm, there are some foods which should be avoided. First of all, reduce your alcohol consumption. A Danish study published in BMJ Open explained that men who want to be a father soon should drink much less alcohol. Scientists have noticed that the more men drink, the lower the quality of their sperm. Their semen contained fewer sperm, and those that were present were of poor quality (abnormal shape and less motile). Moreover, a recent study explained that quitting smoking and drinking could help many couples who are struggling to conceive.Other foods which should be avoided are caffeine and cheese, which is too rich in saturated fatty acids. Above all, do not eat too much fatty food in general. You can still eat fatty food, but like everything else, in moderation!