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Does Grapefruit Seed Extract Kill Candida Yeast?

Updated 1/24/2021

Medically reviewed by Dr. Atmika Paudel, PhD - Written by Dan Jackowiak Nc, HHP and Dr. Vibhuti Rana, PhD

Dr. Atmika Paudel PhD says... The article is backed up by relevant information regarding grapefruit seed extract and its effects on yeasts, its safety issues and is medically correct.

Over the years I have noticed other websites promoting grapefruit seed extract (GSE) as a candida yeast killer. I have also had quite a few people ask me why I did not recommend it? The answer to that quite frankly is, up until now, I have never been able to find any medical proof that it worked. I will not recommend any product for yeast that does not have any real medical studies to back it up. Anyone can say that such and such works for yeast but I simply will not play that game. I suggest you demand the same and ask for the real medical proof that it works before you spend your money.

The studies I have read up until now, suggested that it was the preservatives in the supplements that did the killing. The main preservative in most grapefruit seed extract supplements is none other than potassium sorbate, which I know stops yeast growth dead in its tracks.

Grapefruit Seed Extract Definitely Works


In 2005, a couple of college students at California Polytechnic State University did a study on grapefruit seed extract and its effect on Candida albicans. In their study, they also analyzed the effects of tea tree oil, garlic, (by pressing fresh cloves and using the juice); and the iFlora 6 strain brand of probiotic at a dose of 15 billion bacteria on this yeast. The probiotic contained Bifidobacterium lactis, Lactobacillus acidophilus, Lactobacillus bulgaricus, Lactobacillus casei, Lactobacillus rhamnosus, and Streptococcus thermophilus.

They compared the anti-fungal properties of these natural remedies to the prescription anti-fungal drugs, Miconazole and Amphotericin B. Both drugs completely inhibited the growth of the Candida at the typical suggested doses after two hours. However, the Amphotericin B inhibited growth for a longer period.

The liquid grapefruit seed extract and the Miconazole inhibited the growth of Candida equally. It took them both two hours for full inhibition to take effect and the effects lasted for 16 hours.

Tea tree oil basically had no effect at all. People claim that tea tree oil works for them but considering this study, I suspect that they have bacterial problems and not candida yeast problems.

The probiotic had zero effect. This is not surprising because the typical probiotic contains mostly L. acidophilus and a few species of Bifidobacteria that never work at this low dose. I've seen stool test results to prove this as well. Most probiotic bacteria work by crowding out the candida yeast and they are much more effective if you take something to kill the yeast first. Then the good bacteria will move in and take over the areas where the yeast was, leaving it with no place to go. This is also why I always recommend probiotic doses in the 60 billion or more range, 15 billion is nothing as this study proves.

However, there are probiotic bacteria that have been medically proven to kill candida yeast and I put them in Profase.

The garlic juice extracted from fresh cloves had no inhibitory effect! I must admit that this surprised me. Based on this study, I suspect the women out there who are inserting garlic cloves as vaginal suppositories and claiming it worked for them, actually had bacterial vaginosis and not yeast.

In 2012, a study involving Food Scientists from the College of Food Science and Nutritional Engineering in China, found that GSE killed the yeast Saccharomyces cerevisiae by inducing cell death in the cells by destruction of the mitochondrial 60 S ribosomal protein. It also prevented the conversion of pantothenic acid to coenzyme A.(Source)

Another study in 2001 by Polish scientists Krajewska-Kułak E, Lukaszuk C, Niczyporuk W. found it was effective against Candida albicans and 5 of the Candida sp. strains, but was not effective against dermatophytes and molds.(Source)

Dr. Vibhuti Rana, PhD says...

The information mentioned in the section above has quite clearly described the benefits an antimicrobial activity of the grapefruit seed extract. In a recent study on on dental resins, grapefruit seed extract was found to have an inhibitory effect on the candida albicans biofilms. This study used the colony forming unit CFU assay, fluorescence microscopy, and scanning electron microscopy to study the effect of Polident denture cleansing tablet and grapeseed extract solution on yeast biofilms. This study found that Polident induced the death of yeast but 0.1% GSE could induce the death of hyphae as well as yeast (1).

Another study, in 2004, showed the inhibitory effect of grapefruit seed ethanolic extract on 20 different bacterial strains and ten different yeast strains (2). Another important study in 2004, by Heggars et al., even at 1: 512 dilution of GSE, it proved to be microbicidal and non-toxic to the human skin fibroblast cells. Therefore, even at high dilutions GSE was able to disrupt the bacterial membrane and disperse the cytoplasmic contents of the cells within 15 minutes of contact (3). An important ingredient of GSE is naringenin, the flavonoid with cytoprotective action on the gastric mucosa. GSE exerts protective role against Ischaemia/Repurfusion induced pancreatitis, and uses its antioxidative mechanisms, and improves pancreatic blood flow. (4).

I believe that all these studies demonstrate very efficiently the antibacterial and antifungal role of GSE.

  1. Tsutsumi-Arai C, Takakusaki K, Arai Y, Terada-Ito C, Takebe Y, Imamura T, Ide S, Tatehara S, Tokuyama-Toda R, Wakabayashi N, Satomura K. Grapefruit seed extract effectively inhibits the Candida albicans biofilms development on polymethyl methacrylate denture-base resin. PLoS One. 2019 May 28;14(5):e0217496. doi: 10.1371/journal.pone.0217496. PMID: 31136636; PMCID: PMC6538181.
  2. Acta Pharmaceutica,Vol. 54 No. 3, 2004.
  3. John P. Heggers, John Cottingham, Jean Gusman, Lana Reagor, Lana McCoy, Edith Carino, Robert Cox, and Jian-Gang Zhao.The Journal of Alternative and Complementary Medicine.Jun 2002.333-340.

Grapefruit Seed Extract Safety Concerns

The best thing for me to do here is to direct you to this webpage at RXlist.

In Conclussion:

Grapefruit seed extract is a very good candida yeast killer but I do suggest you click on over to RXlist and see if you fall into any of those safety categories. Or, consult with your doctor or pharmacist before taking it.

The students in the Cal Poly study used this grapefruit seed extract. It also comes in a capsule form.

Dr. Vibhuti Rana, PhD says...

Excessive consumption of GSE or grapefruit juice have been linked to breast cancer in post-menopausal women, or those with cardiovascular complications. There are not any sufficient studies in pregnant or lactating women. More importantly, it can interact with some drug classes and lead to their increased side-effects/ activity. For example, some of these drugs are Buspiron, Carbamazapine, Carvedilol, Statins, Cytochrome P450 3A4 substrates, benzodiazepines (sedatives), or Cordarones.

Therefore, while GSE is very effective in treating a number of microbial problems, it's use and dosage should be very carefully controlled by consulting a physician.

Medical Review by Dr. Atmika Paudel, PhD

The article is well-written and the backed up by evidences. Many studies that were performed with the commercial grape fruit seed extracts are shown to have antimicrobial activities(1)(2),  and protective effect against pancreatitis (3). The literatures cited in the above article also have used commercial grape fruit seed extracts.

Some studies, as the article above states, have mentioned that the antimicrobial activity in commercial grape fruit seed extracts were due to the presence of other synthetic substances such as benzethonium chloride (4), and the presence of these synthetic substances was less likely to have formed during the extraction procedure.

A study that was published in 2004 in Acta Pharmaceutica did not use a commercial product, rather they did the ethanolic extraction of the grape fruit seed and tested the extract for antimicrobial activity. The study demonstrated that the grape fruit seed extract had antimicrobial activities against bacteria and some yeasts. The extract was effective against Gram positive bacteria and fungi such as Candida albicans and Candida tropicalis, but was not effective against Gram negative bacteria.(5)

Grape fruit seed extract supplement was found to have adverse effects such as nausea, vomiting, diarrhea and acute weakness in a man after he started using grape fruit seed extract supplement. No other clinical cause was found and the symptoms gradually ceased after discontinuation of grape fruit seed extract supplement. (6)

1. The Journal of Alternative and Complementary MedicineVol. 8, No. 3 The Effectiveness of Processed Grapefruit-Seed Extract as An Antibacterial Agent: II. Mechanism of Action and In Vitro Toxicity, Published Online:5 Jul 2004
2. Grapefruit seed extract effectively inhibits the Candida albicans biofilms development on polymethyl methacrylate denture-base resin Published: May 28, 2019, PLOS ONE
3. EXTRACT OF GRAPEFRUIT-SEED REDUCES ACUTE PANCREATITIS INDUCED BY ISCHEMIA/REPERFUSION IN RATS; POSSIBLE IMPLICATION OF TISSUE ANTIOXIDANTS *Department of Physiology, Jagiellonian University Medical School, Cracow, Poland **Department of Clinical Biochemistry, Jagiellonian University Medical School, Cracow, Poland. JOURNAL OF PHYSIOLOGY AND PHARMACOLOGY 2004, 55, 4, 811821
4. Identification of Benzethonium Chloride in Commercial Grapefruit Seed Extracts Gary Takeoka,*, Lan Dao,Rosalind Y. Wong,Robert Lundin, and, and Noreen Mahoney Journal of Agricultural and Food Chemistry 2001 49 (7), 3316-3320
DOI: 10.1021/jf010222w 
5. Cvetnić, Zdenka; Vladimir-Knežević, Sanda. Antimicrobial activity of grapefruit seed and pulp ethanolic extract // Acta pharmaceutica, 54 (2004), 243-250 .
6. Andrew C. Berry, Rahman Nakshabendi, Hussein Abidali, Kunakorn Atchaneeyasakul, Kevin Dholaria, Cassandra Johnson, Varsha A. Kishore & Aaron C. Baltz (2016) Adverse Effects of Grape Seed Extract Supplement: A Clinical Case and Long-Term Follow-Up, Journal of Dietary Supplements, 13:2, 232-235, DOI:

Have Any Questions About Grapefruit Seed Extract?

Do you have any questions about grapefruit seed extract or yeast infections in general? Ask your question here or contact us using the contact page of this website. It is also always a good idea to talk to your doctor as well.

It is also found in Microfase

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