There are many forms of grapefruit extract available, which can be taken both – internally and externally. GSE taken internally is usually in a form of powder or liquid concentrate which is mixed with water or other drinks, or in a form of capsules, which are swallowed. Taking Grapefruit seed extract internally It helps the body eliminate harmful oxidants that cause various health problems. It is highly beneficial to the immune system, as it helps in the preservation of the intestinal bacteria that help fight the disease causing germs. Another form of grapefruit seed extract are creams, which are used to treat skin problems. Grapefruit seed extract is used in antibiotics as well.