The reason eating citrus fruits appears to protect against cancer may be because of DNA repair enzyme-boosting powers of a compound concentrated in the peel.
Citrus Peels and Cancer: Zest for Life?
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New data demonstrating a DNA protective agent was present in at least some fruits and vegetables found that the agent was heat sensitive and determined it was not vitamin C. This was confirmed in a study that tried vitamin C directly and found no effect on DNA protection and repair of DNA strand breaks.
The carotenoid beta cryptoxanthin, found primarily in citrus, seems to be at least one candidate. If you expose cells to a mutagenic chemical, you can cause physical breaks in the strands of DNA, but in less than an hour, our DNA repair enzymes can weld most of our DNA back together. But if you add some of that citrus phytonutrient, you can effectively double the speed at which the DNA is repaired. But this is all just cells in a petri dish, what about in a person?
If you have people drink a glass of orange juice and draw their blood two hours later, the DNA damage you can induce with an oxidizing chemical drops, whereas if they just had like orange Kool-Aid, it didn’t help.
So, do people who eat more fruit walk around with less DNA damage? Yes, particularly in women. Does this actually translate into lower cancer rates? Yes, citrus alone is associated with a 10% reduction in odds of breast cancer.
Given to newly diagnosed breast cancer patients, citrus phytonutrients were found to concentrate in breast tissue, though many complained of “citrus burps” due to the concentrated extract they were given; so, researchers evaluated topical application as an alternative dosing strategy, recruiting women to apply orange flavored massage oil to their breasts daily. This request was met with excellent compliance, but it didn’t work. We actually have to eat our food.
Why not just take carotenoid supplements to boost our DNA repair? Because it doesn’t work. Although dietary supplements did not provoke any alteration in DNA repair, dietary supplementation with carrots did. This suggests that the whole food may be important in modulating DNA repair processes.
Though orange juice consumption was found protective against childhood leukemia, it was not found protective against skin cancer. However, the most striking feature was the protection purported by citrus peel consumption. Who eats orange peels? Lots of people evidently. Just drinking orange juice may increase the risk of the most serious type of skin cancer. Daily consumption was associated with a 60% increase in risk; so again, better to stick with the whole fruit. And you can eat citrus extra-whole by zesting some of the peel into your dishes.
To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Katie Schloer.
Please consider volunteering to help out on the site.
- Y T Szeto, T L To, S C Pak, W Kalle. A study of DNA protective effect of orange juice supplementation. Appl Physiol Nutr Metab. 2013 May;38(5):533-6.
- J Slyskova, Y Lorenzo, A Karlsen, M H Carlsen, V Novosadova, R Blomhoff, P Vodicka, A R Collins. Both genetic and dietary factors underlie individual differences in DNA damage levels and DNA repair capacity. DNA Repair (Amst). 2014 Apr;16:66-73.
- A R Collins, A Azqueta, S A Langie. Effects of micronutrients on DNA repair. Eur J Nutr. 2012 Apr;51(3):261-79.
- A Azqueta, S Costa, Y Lorenzo, N E Bastani, A R Collins. Vitamin C in cultured human (HeLa) cells: lack of effect on DNA protection and repair. Nutrients. 2013 Apr 9;5(4):1200-17.
- S B Astley, R M Elliott, D B Archer, S Southon. Evidence that dietary supplementation with carotenoids and carotenoid-rich foods modulates the DNA damage: repair balance in human lymphocytes. Br J Nutr. 2004 Jan;91(1):63-72.
- Y Lorenzo, A Azqueta, L Luna, F Bonilla, G Domínguez, A R Collins. The carotenoid beta-cryptoxanthin stimulates the repair of DNA oxidation damage in addition to acting as an antioxidant in human cells. Carcinogenesis. 2009 Feb;30(2):308-14.
- Y T Szeto, W K Chu, I F Benzie. Antioxidants in fruits and vegetables: a study of cellular availability and direct effects on human DNA. Biosci Biotechnol Biochem. 2006 Oct;70(10):2551-5.
- D Feskanich, W C Willett, D J Hunter, G A Colditz. Dietary intakes of vitamins A, C, and E and risk of melanoma in two cohorts of women. Br J Cancer. 2003 May 6;88(9):1381-7.
- M L Kwan, G Block, S Selvin, S Month, P A Buffler. Food consumption by children and the risk of childhood acute leukemia. Am J Epidemiol. 2004 Dec 1;160(11):1098-107.
- J A Miller, J E Lang, M Ley, R Nagle, C H Hsu, P A Thompson, C Cordova, A Waer, H H Chow. Human breast tissue disposition and bioactivity of limonene in women with early-stage breast cancer. Cancer Prev Res (Phila). 2013 Jun;6(6):577-84.
- I A Hakim, R B Harris, C Ritenbaugh. Citrus peel use is associated with reduced risk of squamous cell carcinoma of the skin. Nutr Cancer. 2000;37(2):161-8.
- J K Song, J M Bae. Citrus fruit intake and breast cancer risk: a quantitative systematic review. J Breast Cancer. 2013 Mar;16(1):72-6.
- J A Miller, P A Thompson, I A Hakim, A M Lopez, C A Thomson, W Chew, C H Hsu, H H Chow. Safety and Feasibility of Topical Application of Limonene as a Massage Oil to the Breast. J Cancer Ther. 2012 Oct;3(5A).
Images thanks to PublicDomainPictures via Pixabay.
New data demonstrating a DNA protective agent was present in at least some fruits and vegetables found that the agent was heat sensitive and determined it was not vitamin C. This was confirmed in a study that tried vitamin C directly and found no effect on DNA protection and repair of DNA strand breaks.
The carotenoid beta cryptoxanthin, found primarily in citrus, seems to be at least one candidate. If you expose cells to a mutagenic chemical, you can cause physical breaks in the strands of DNA, but in less than an hour, our DNA repair enzymes can weld most of our DNA back together. But if you add some of that citrus phytonutrient, you can effectively double the speed at which the DNA is repaired. But this is all just cells in a petri dish, what about in a person?
If you have people drink a glass of orange juice and draw their blood two hours later, the DNA damage you can induce with an oxidizing chemical drops, whereas if they just had like orange Kool-Aid, it didn’t help.
So, do people who eat more fruit walk around with less DNA damage? Yes, particularly in women. Does this actually translate into lower cancer rates? Yes, citrus alone is associated with a 10% reduction in odds of breast cancer.
Given to newly diagnosed breast cancer patients, citrus phytonutrients were found to concentrate in breast tissue, though many complained of “citrus burps” due to the concentrated extract they were given; so, researchers evaluated topical application as an alternative dosing strategy, recruiting women to apply orange flavored massage oil to their breasts daily. This request was met with excellent compliance, but it didn’t work. We actually have to eat our food.
Why not just take carotenoid supplements to boost our DNA repair? Because it doesn’t work. Although dietary supplements did not provoke any alteration in DNA repair, dietary supplementation with carrots did. This suggests that the whole food may be important in modulating DNA repair processes.
Though orange juice consumption was found protective against childhood leukemia, it was not found protective against skin cancer. However, the most striking feature was the protection purported by citrus peel consumption. Who eats orange peels? Lots of people evidently. Just drinking orange juice may increase the risk of the most serious type of skin cancer. Daily consumption was associated with a 60% increase in risk; so again, better to stick with the whole fruit. And you can eat citrus extra-whole by zesting some of the peel into your dishes.
To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Katie Schloer.
Please consider volunteering to help out on the site.
- Y T Szeto, T L To, S C Pak, W Kalle. A study of DNA protective effect of orange juice supplementation. Appl Physiol Nutr Metab. 2013 May;38(5):533-6.
- J Slyskova, Y Lorenzo, A Karlsen, M H Carlsen, V Novosadova, R Blomhoff, P Vodicka, A R Collins. Both genetic and dietary factors underlie individual differences in DNA damage levels and DNA repair capacity. DNA Repair (Amst). 2014 Apr;16:66-73.
- A R Collins, A Azqueta, S A Langie. Effects of micronutrients on DNA repair. Eur J Nutr. 2012 Apr;51(3):261-79.
- A Azqueta, S Costa, Y Lorenzo, N E Bastani, A R Collins. Vitamin C in cultured human (HeLa) cells: lack of effect on DNA protection and repair. Nutrients. 2013 Apr 9;5(4):1200-17.
- S B Astley, R M Elliott, D B Archer, S Southon. Evidence that dietary supplementation with carotenoids and carotenoid-rich foods modulates the DNA damage: repair balance in human lymphocytes. Br J Nutr. 2004 Jan;91(1):63-72.
- Y Lorenzo, A Azqueta, L Luna, F Bonilla, G Domínguez, A R Collins. The carotenoid beta-cryptoxanthin stimulates the repair of DNA oxidation damage in addition to acting as an antioxidant in human cells. Carcinogenesis. 2009 Feb;30(2):308-14.
- Y T Szeto, W K Chu, I F Benzie. Antioxidants in fruits and vegetables: a study of cellular availability and direct effects on human DNA. Biosci Biotechnol Biochem. 2006 Oct;70(10):2551-5.
- D Feskanich, W C Willett, D J Hunter, G A Colditz. Dietary intakes of vitamins A, C, and E and risk of melanoma in two cohorts of women. Br J Cancer. 2003 May 6;88(9):1381-7.
- M L Kwan, G Block, S Selvin, S Month, P A Buffler. Food consumption by children and the risk of childhood acute leukemia. Am J Epidemiol. 2004 Dec 1;160(11):1098-107.
- J A Miller, J E Lang, M Ley, R Nagle, C H Hsu, P A Thompson, C Cordova, A Waer, H H Chow. Human breast tissue disposition and bioactivity of limonene in women with early-stage breast cancer. Cancer Prev Res (Phila). 2013 Jun;6(6):577-84.
- I A Hakim, R B Harris, C Ritenbaugh. Citrus peel use is associated with reduced risk of squamous cell carcinoma of the skin. Nutr Cancer. 2000;37(2):161-8.
- J K Song, J M Bae. Citrus fruit intake and breast cancer risk: a quantitative systematic review. J Breast Cancer. 2013 Mar;16(1):72-6.
- J A Miller, P A Thompson, I A Hakim, A M Lopez, C A Thomson, W Chew, C H Hsu, H H Chow. Safety and Feasibility of Topical Application of Limonene as a Massage Oil to the Breast. J Cancer Ther. 2012 Oct;3(5A).
Images thanks to PublicDomainPictures via Pixabay.
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Title
Citrus Peels and Cancer: Zest for Life?
LicenseCreative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)
Content URLDoctor's Note
That’s why my favorite citrus fruit is kumquat—because you can eat the peel and all!
For other foods that may keep our DNA intact, see my Which Fruits and Vegetables Boost DNA Repair? video. Kiwifruit (Kiwifruit and DNA Repair), broccoli (DNA Protection from Broccoli), and spices (Spicing Up DNA Protection) may also fit the bill.
More on citrus in Keeping Your Hands Warm With Citrus and Reducing Muscle Fatigue With Citrus, and Can Vitamin C Help with Lead Poisoning?.
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