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Grapefruit seed extract uses are numerous due to its action as a highly concentrated, natural general antimicrobial and antioxidant. Benefits include killing all kinds of infectious microbes—bacterial, viral, and fungal—at least in test tube and animal studies.[1,2]
What’s in Grapefruit Seed Extract?
The main compounds in grapefruit seeds thought to be responsible for its ability to kill infectious agents are chemical compounds (polyphenols) known as limonoids and naringenin.
These intensely powerful compounds act as antimicrobials and antioxidants, not only killing dangerous microbes but protecting the body’s tissues against the excessive production of reactive oxygen species which occurs when these pathogens infect the tissues.
A grapefruit extract dosage may come in a number of different delivery forms and concentrations. Liquids and/or capsules can be used whether the infection is on the skin; in the ears, nose, or mouth; or in the gastrointestinal tract. Grapefruit seed extract is also used as a preservative and antimicrobial in natural personal care products as well as by the food industry for food preservation.
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Warnings About Grapefruit Seed Extract
Grapefruit juice and possibly other grapefruit products, including grapefruit seed extract, are known to interact with certain drugs and may lead to serious adverse reactions. Grapefruit inhibits certain enzyme systems within the body most often involved in drug metabolism. This increases blood concentrations of the drugs concerned, creating a risk of overdose and dose-dependent adverse effects. Grapefruit seed extract can sometimes cause skin irritation when used topically. The liquid grapefruit seed concentrates should always be diluted; never use full strength and avoid contact with eyes or other sensitive areas.
Also, in a report published in 2012, investigators from the Austin, Texas-based American Botanical Council found that many grapefruit seed extract products on the market today contain synthetic chemicals that aren’t listed on their labels. They report that any antimicrobial activities in grapefruit extract products is likely due to these synthetic additives, and not the grapefruit extract itself. Since the actual amount of these unlisted chemicals could vary widely and are unapproved compounds for internal use, some natural health practitioners recommend not taking GSE health products internally. If you’re considering the use of grapefruit seed extract in treatment of a chronic condition, make sure to consult your physician.
How to Take Grapefruit Seed Extract Internally to Fight Infections
Grapefruit seed extract concentrated liquid and capsules should not be taken by children except under a doctor’s supervision. Adults can mix 10 drops of the liquid concentrate into a glass of water or juice (5 oz. or more) and drink, 1-3 times daily, with or without meals. Note that grapefruit seed extract is extremely bitter. To avoid the bitter taste, adults may also take one to two 250 mg capsules one to two times daily with or without meals.
Grapefruit extract can deplete normal flora (healthy “good” bacteria) in the gut when taken long-term. If you plan to take GSE for 3 days or more, it’s important to consume a probiotic supplement two hours before taking your GSE dose.
GSE Benefits Include Killing Candida and Treating Digestive Symptoms
Grapefruit seed extract is perhaps best known for its ability to treat digestive disturbances and kill pathogens, especially fungal pathogens like Candida albicans, in the gastrointestinal tract. One preliminary human trial investigated the effectiveness of grapefruit seed extract in people with symptoms of irritable bowel syndrome (IBS) and eczema. Subjects received either 2 drops of a 0.5% liquid concentrate twice a day or 150 mg of encapsulated grapefruit seed extract (ParaMicrocidin®) three times a day.
After a month, all of the subjects taking capsules experienced significant improvements in constipation, flatulence, and abdominal discomfort, as well as night rest, while 20% of the subjects taking the liquid experienced significant improvements in their IBS symptoms. Results found that there were no major grape seed extract side effects. The fact that these patients’ digestive symptoms improved with grapefruit extract suggests that they actually had an infection in the gastrointestinal tract that was causing their symptoms rather than IBS. And in fact, the researchers tested the extract against different intestinal pathogens and found it was most effective against Candida species, a type of fungal infection, and some types of parasites.
Grapefruit Seed Extract Uses
Among the multiple uses include:
- Throat gargle (for colds and sore throats)
- Mouth wash (for gums and dental health)
- Nasal/sinus wash (for sinus infections and colds)
- Ear drops
- Digestive disturbances (including candida and traveler’s diarrhea)
- Skin wounds
- Fruit and veggie wash
In addition to grapefruit seed oil, liquid extracts and capsules, some companies, like Nutribiotics, make throat sprays, nasal sprays, ear drops, mouthwashes and gargles, toothpastes, shower gels, wound disinfectant sprays, and other personal care products containing grapefruit seed extract and other ingredients. Follow the label instructions for use.
 Acta Pharm. 2004 Sep;54(3):243-50.
 J Altern Complement Med. 2002 Jun;8(3):333-40.
Originally published in 2013, this post is regularly updated.