Grapefruit extract is the only way to go, don't do the juice. Its under $10 at most health food stores and such and it does so much.
(Cut and Paste)
It has a wide variety of uses. It has gained a reputation as being supportive for people with digestive upsets, flus, colds, and sore throats. It has been recommended by several leading medical doctors/authors for relief of symptoms associated with yeast imbalance. A wide array of topical applications also exist. It is recommended by nutritionists, chiropractors, acupuncturists, and other health practitioners as an effective alternative product in their practice.
When I get a sore throat or start to get sick, I mix it in water and gargle with it. Within 2 days I am all better. I also use it daily to increase absorption of supplements. I also suggest you do a search here on Elite about it.