However, there are cases where the color may appear yellowish, sometimes referred to as âyellow spermâ or âyellow semenâ. The cause of yellow sperm is uncertain but it is believed that it can be caused by infection, or foods which are rich in sulfur such as garlic and onions.Another possible cause for yellow semen could be the natural thickening of semen; especially if you have not ejaculated for quite some time.he cause of yellow sperm is uncertain but it is believed that it can be caused by infection, or foods which are rich in sulfur such as garlic and onions.
Avoid certain foods. Starting 1 week before your colonoscopy, do not eat raw fruits and vegetables, whole kernel corn, grains or seeds, such as poppy or sesame, or nuts. These foods are hard to digest and may make it hard for your doctor to see during your colonoscopy.
Three days before your colonoscopy, eat only low-fiber foods listed below. Two days before, continue eating only low-fiber foods. Print this chart (PDF) for easy reference.