Probiotics are organisms that live in our digestive system. They consist of bacteria and fungi, and with over 500 different types living within the digestive tract it is very important that the useful ones are predominant. Bad bacteria or fungal overgrowth like candida can be very detrimental to health. Taking a probiotic supplement of 'good' bacteria ensures that a healthy balance is maintained and that we can get all the nutrients we need from the food we eat.
As the name suggests antibiotics are designed to kill biota, or living organisms. When we take a broad spectrum antibiotic to deal with an infection it kills not only the harmful bacteria that make us ill, but many of the 'good' bacteria in our digestive system that we need for good health.
These bacteria need to be replaced after a course of antibiotics, as without them our body cannot draw the essential nutrients it needs from food properly, compromising the immune system and leaving the body open to further infections.
Our digestive system is one of the first lines of immune defense and if it is not functioning properly because of an imbalance in gut flora it can soon lead to more serious problems.