Grapefruits have therapeutic effects for DNA repair, cancer inhibition, insulin resistance and skin photo-aging

With this season’s hot summer, grapefruits are all the more indicated that they have many happy health properties, including the ability to repair DNA mutations (SECTION A),  the capacity to fight cancer (SECTION B) and even the know-how to efficiently deal with metabolic dysfunctions like obesity and insulin resistance, to which the partial reversal of photo-aging of the skin can be added. (SECTION C).



Scientists have discovered two compounds found in grapefruit that can aid in repairing DNA damage. The first molecule is naringenin, a bioflavonoid found in all citrus fruits in very small amounts, with an abundance in grapefruit. The evidence that supports this claim was first established in a 2006 study with human prostate cancer cells. This study concluded that naringenin was able to aid in restoring health to damaged DNA through the induction of two enzymes that work during the cell replication stage.

“As part of a systematic study of the effects of phytochemicals beyond antioxidation on cancer prevention, we investigated whether naringenin (NR), a citrus flavonoid, stimulates DNA repair following oxidative damage in LNCaP human prostate cancer cells. (…) In conclusion, the cancer-preventive effects of citrus fruits demonstrated in epidemiological studies may be due in part to stimulation of DNA repair by NR, which by stimulating BER processes may prevent mutagenic changes in prostate cancer cells”. (1) (Source)



In yet another study, naringenin was found to inhibit both human colorectal and breast cancer cell growth in a dose and time dependent manner through its actions on the cell cycle and its ability to promote apoptosis (ie planned cell death). It was also found to alter the expression of cell cycle regulatory genes to down regulate cancer cells.

“Natural products with diverse bioactivities are becoming an important source of novel agents with medicinal potential (…) In the present study, thymus vulgaris ethanol extract was purified repeatedly to produce several compounds including the known flavanone, Nar which was identified using different spectral techniques. Nar was shown to inhibit both human colorectal and breast cancer cell growth in a dose- and time-dependent manner through cell cycle arrest at S-and G2/M-phases accompanied by an increase in apoptotic cell death. Additionally, Nar altered the expression of apoptosis and cell-cycle regulatory genes by down-regulating Cdk4, Cdk6, Cdk7, Bcl2, x-IAP and c-IAP-2 and up-regulating p18, p19, p21, caspases 3, 7, 8 and 9, Bak, AIF and Bax in both colorectal and breast cancer cells…..” (2) (Source)

In addition to naringenin, grapefruits also contain an abundance of apigenin, which is another bioflavonoid found in high amounts in grapefruit as well as in oranges, parsley, onions, and chamomile tea. It has antioxidant, anti-inflammatory effects and multiple anti-tumor properties.

In this perspective, via a study completed in 2014, apigenin was shown to inhibit DNA synthesis in a panel of human breast cancer cell lines. This resulted in decreased cell proliferation and cell cycle arrest. Researchers concluded that low-dose apigenin has the potential to slow or prevent breast cancer progression.

“Epidemiological studies show that fruit- and vegetable-rich diets are associated with a reduced risk of developing certain forms of cancer, including breast cancer. In this study we demonstrate that a subcytotoxic concentration of apigenin, which is a flavone found at high concentrations in parsley, onions, grapefruit, oranges, and chamomile tea, inhibited DNA synthesis in a panel of human breast cancer cell lines (….) Taken together, these findings suggest that low-dose apigenin has the potential to slow or prevent breast cancer progression”. (3) (Source)



Grapefruits have been part of multiple trendy weight loss plans. In support of this claim, one animal study showed that grapefruit juice promoted weight loss, improved fasting blood glucose, lowered fasting serum insulin levels and reduced triglycerides when compared to controls. Grapefruits were also also compared favorably to metformin in reducing weight, fasting blood glucose and serum insulin levels. (Source)

In still another study, a human one, some of these health effects were corroborated.

“In metabolic syndrome patients the effect was also seen with grapefruit products. Insulin resistance was improved with fresh grapefruit. Although the mechanism of this weight loss is unknown it would appear reasonable to include grapefruit in a weight reduction diet”. (Source)

Regarding skin protection, the grapefruit needs to be pink or reddish, as this colors means that there is an abundance of lycopene, a carotenoid laden with multiple health effects, including in the slowing down of skin aging by stabilizing the DNA structure in the nucleus of skin cells and inhibiting enzymes involved in collagen destruction.

“… Application of topical lycopene prevented the cleavage of caspase-3. UVB irradiation completely diminished proliferating cell nuclear antigen (PCNA), and the untreated skin maintained positively stained cells throughout the basal epidermis. Topical application of lycopene significantly reversed UVB-induced PCNA inhibition, and normal PCNA staining was restored in the lycopene-treated skin. Our results suggest that topical lycopene is able to exert its protective effects against acute UVB-induced photodamage. Furthermore, it may act as a preventative agent via inhibition of epidermal ornithine decarboxylase activity, reducing inflammatory responses, maintaining normal cell proliferation, and possibly preventing DNA damage as indicated by blocking the necessitating step of apoptosis following UVB injury. (4) (Source)



For best results, the research data suggests eating fresh organic grapefruits through-out the day, including half an hour before meals when possible. (8) The advantage of whole grapefruits is based on the fact that it’s white pulp contains quercetin, another great anti-aging molecule and lots of seeds, rich in many valuable phyto-nutrients. I would even suggest a little of its peel, rich in limonene and other interesting substances, all of which can be blended with other superfoods as a smoothie, including sugar stabilizing cinnamon.

While much less glycemic than orange juice, grapefruit juice, especially pasteurized, can still be a health problem, as it is deficient in fiber and enzyms. Unless one consumes lots of fiber and good fats at the same time or a few minutes after drinking it, the best being fresh organic grapeful juice as this will slow down insulin production. Spreading grapefruit juice topically over the skin before going into the sun, maybe mixed with coconut oil for additional UVB protection, could also be an interesting idea. As noted elsewhere, we don’t want too much protection against UVBs because these are the rays that also produce the needed vitamin D3 and they also boost hormones. Balance is key. And in this realm, most natural molecules are usually safer and more efficiently than synthetic ones.

Pr. Joubert (ACR Institute director)



(1). J Nutr Biochem. 2006 Feb;17(2):89-95.
The citrus flavonoid naringenin stimulates DNA repair in prostate cancer cells.
Gao K1, Henning SM, Niu Y, Youssefian AA, Seeram NP, Xu A, Heber D.
(2)  Cancer Cell Int. 2015 Apr 24;15:46.
Growth inhibitory and chemo-sensitization effects of naringenin, a natural flavanone purified from Thymus vulgaris, on human breast and colorectal cancer.
Abaza MS1, Orabi KY2, Al-Quattan E1, Al-Attiyah RJ3.
(3)   Exp Mol Pathol. 2014 Oct;97(2):211-7.
Exposure of breast cancer cells to a subcytotoxic dose of apigenin causes growth inhibition, oxidative stress, and hypophosphorylation of Akt.
Harrison ME1, Power Coombs MR2, Delaney LM1, Hoskin DW3.
(4). Lycopene, an acyclic hydrocarbon carotenoid found in tomatoes and other red and pink fruits and vegetables, is a well-established potent antioxidant, and its anticancer properties have been shown in cultured cells and animal models. Cf  Ultraviolet B-Induced Photodamage
Zsuzsanna Fazekas , Dayuan Gao , Rao N. Saladi , Yuhun Lu , Mark Lebwohl & Huachen Wei, Journal Nutrition and Cancer, Volume 47, 2003 – Issue 2
(5). Eating grapefruits or drinking its juice during a meal that contains grains and starches may not be a good idea because that would spur flatulence and indigestion issues, as the fruit’s acid will tend to use the meal’s starches to ferment. As a general rule, fruits should be taken at least one half hour before meals, or three hours after meals.
Disclaimer: Nothing in this educational post should be construed as medical advise
2016 (c). Advanced Cancer Research Institute. All rights reserved.

Professor Joubert teaches how to extend a healthy cancer-free Lifespan to 122 years thanks to safe, efficient and cost friendly breakthrough protocols. Working on a documentary and book that redefines Medicine in light of ancient wisdoms, innovative research, holistic science and new discoveries with regard to quantic, microbiota et epigenetic findings, he can be available to coach patients back to homeostasis, wellbeing, Joie de vivre and healthy supercentenarian aging.

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