Hippocrates’ counsel, “Let food be your medicine,” offers much wisdom to us today. Besides providing a liberal supply of vitamin C, potassium, and fiber, what other medicinal value do citrus fruits offer?
Regular consumption of citrus fruits reduces your risk of developing a host of cancers including skin, lung, breast, oral, and colon cancer. How does citrus pull off such a noble feat?
One partial answer lies with hesperetin (and a related compound called hesperidin), the predominant flavonoid in lemons and oranges. By way of review, the flavonoids are a group of naturally occurring plant pigments (i.e. a class of phytochemicals) whose name derives from the Latin flavus meaning yellow. The flavonoid family has far-reaching health benefits, with hesperitin grabbing a lot of the limelight when it comes to cancer prevention.
Hesperitin, along with other citrus bioflavonoids, helps counter cancer through a number of mechanisms. They possess anti-inflammatory and antioxidant properties and have been demonstrated to prevent cancer development, squelch cancer growth, and even enhance the efficacy of cancer chemotherapy drugs if a person elects to go that route.1 Some of those benefits occur by blocking the growth of new blood vessels to supply the cancerous tissue (so the rapidly growing tumor cannot sustain itself). Still other benefits occur by stimulating the “programmed death” of cancer cells, a process known as apoptosis.2 Additionally, a growing body of research suggests that hesperidin may help healthy cells be more resistant to chemotherapy side effects.3
As exciting as the flavonoids are, citrus fruits contain still more cancer-fighting phytochemicals. Consider the limonoids which, in themselves, show promise in preventing and/or treating two of the Western world’s leading cancers: estrogen-responsive breast cancer and colon cancer. When you eat a piece of citrus and notice a somewhat bitter flavor, that is the limonoid you are tasting. Because of this, the citrus industry considers limonoids undesirable and eliminates them from processed citrus as much as possible.
Two caveats are in order. First, since many of these anti-cancer compounds are located in the white part immediately under the fruit’s peel, store-bought juices might not deliver optimal amounts. If you eat (or drink) only the sweetest citrus options, you get less limonoids than if you had more variety.
Multiple Cardiovascular Protectors
Frequent consumption of citrus may lower one’s risk for stroke and other cardiovascular diseases. It is clear this effect is due to something beyond vitamin C, as multiple studies have demonstrated that vitamin C alone offers no cardiac protection.
Both citrus flavonoids and limonoids play roles in decreasing cholesterol production and thus lowering cholesterol levels. Some of these compounds also show promise for helping decrease other heart disease risk factors by improving blood pressure control and lowering blood sugar in those with diabetes (through insulin-sensitization). These compounds as well, decrease the formation of vessel-damaging oxidized cholesterol (owing to antioxidant effects).4 One particularly fascinating study demonstrated that hesperidin in oranges modulates the gene activity of white blood cells so as to protect against inflammation and atherosclerosis.5 Finally, citrus flavonoids, by inhibiting red blood cells and platelet clumping, improve the oxygen-carrying capacity of the red blood cells and blood flow through tiny capillaries.
Citrus Helps the Brain
Citrus flavonoids also appear to be highly effective in preventing age-related cognitive decline in both animals and humans. These essentially non-toxic compounds readily cross the “blood-brain barrier,” thus gaining direct access to our brains. Besides protecting our cerebral cells from free radical damage through their antioxidant features, their anti-inflammatory nature combats inflammatory assaults commonly seen in diseases like Parkinson’s and Alzheimer’s.6
The brain-enhancing properties of citrus extend to their fragrance. The mere aroma of these fruits has been found to help normalize suppressed immune and neuroendocrine functions in depressed patients—and concomitantly improve their mental outlook.7 Lemon fragrance specifically ameliorates fatigue and helps maintain mental vigor when performing simple mental tasks. So, don’t forget to include citrus in your diet—or at least in your olfactory environment—if you are looking for some additional ways to gain a mental edge.
Citrus Is Not For Everyone
Some studies show that as many as 25% of their participants experience allergies from consumption of citrus fruits. Citrus fruits have been ranked among the top five offenders in food allergies.
Avoid citrus in children before twelve months old due to acid-induced rash or GI upset. Seville oranges, grapefruit, limes, and pomelos contain furano cumarins that disrupt the breakdown of certain drugs. Check the pharmacy insert for any medicine that you are taking.
Individuals with pre-diabetes or diabetes should avoid fruit juice as they raise the blood glucose and triglycerides levels.
Citrus fruits are packed with a host of powerful disease-fighting compounds. Indeed, their list of benefits is impressive. Nonetheless, do not eat citrus for the limonoids or hesperitin as a way of treating medical conditions without discussing it with your doctor.
But, as long as you don’t have an allergy or intolerance to this health-enhancing family of foods—and aren’t taking medications which could be adversely affected by grapefruit consumption—eating liberally from citrus sources is a valuable addition to your diet.
- Meiyanto, E., Hermawan, A. Natural products for cancer-targeted therapy: citrus flavonoids as potent chemopreventive agents. Asian Pac J Cancer Prev. 2012; 13(2):427-36.↩
- Nalini, N., et al. Chemopreventive efficacy of hesperetin (citrus flavonone) against 1, 2-dimethylhydrazine-induced rat colon carcinogenesis. Toxicol Mech Methods. 2012 Jun; 22(5):397-408.↩
- Sahu, B.D., et al. Hesperidin attenuates cisplatin-induced acute renal injury by decreasing oxidative stress, inflammation and DNA damage. Phytomedicine. 2013 Mar 15; 20(5):453-60.↩
- Tangney, C.C., Rosenson, R.R. Nutritional antioxidants in coronary heart disease. Up-to-date; topic update of Apr 10, 2012.↩
- Milenkovic, D., et al. Hesperidin displays relevant role in the nutrigenomic effect of orange juice on blood leukocytes in human volunteers: a randomized controlled cross-over study. PLoS One. 2011; 6(11):e26669.↩
- Spencer, J.P., et al., Neuroinflammation: modulation by flavonoids and mechanisms of action. Mol Aspects Med. 2012 Feb; 33(1):83-97.↩
- Komori, T., et al. Effects of citrus fragrance on immune function and depressive states. Neuroimmunomodulation. 1995 May-Jun; 2(3):174-80.↩