Citrus Fruits Pack a Healthy Punch

A grapefruit a day keeps the doctor away?

Reviewed by Brunilda Nazario, MD on September 02, 2004
From the WebMD Archives

Aug. 24, 2004 -- Self-proclaimed "miracle" diets claim grapefruit can cause unwanted pounds to fall right off.

The low-carb conscious say citrus fruits are a no-no when it comes to losing weight.

Doctors have long warned that grapefruit juice can interact in a dangerous fashion with certain prescription medications, such as blood pressure drugs.

Are citrus fruits good or bad for you?

The citrus controversy has led to a decline in the consumption of such fruits as the public is left wondering whether or not they do the body good. Now, emerging (albeit early) evidence shows that oranges, grapefruits, even tangerines have the power to fight life-threatening diseases such as cancer, obesity, and high cholesterol.

Researchers from around the world presented the findings during a two-day symposium at the 228th national meeting of the American Chemical Society this week in Philadelphia.

Among the highlights:

  • Compound in citrus fruits may prevent colon cancer. Citrus fruits are rich in cancer-fighting compounds. Nancy D. Turner and colleagues from Texas A&M University reported that feeding freeze-dried grapefruit pulp (with properties similar to whole grapefruit) reduced the number of precancerous lesions of the colon in lab rats made to have colon cancer. Rikako Suzuki of Kyoto University in Japan extracted the cancer chemopreventative compound nobiletin from citrus fruit and found it helped prevent colon cancer in animal studies.
  • Grapefruit does work for dieters. The grapefruit diet has had its critics, but there is some science to back up the idea after all (although a diet consisting only of grapefruit is still considered extreme). Scripps Clinic scientist Ken Fujioka presented findings from a 12-week study examining how grapefruit and grapefruit products affected the weight and metabolism of 100 obese patients. At the end of 12 weeks he concluded that eating grapefruit does promote weight loss. He also says that people with the metabolic syndrome respond to both grapefruit juice and grapefruit. They say the weight loss attributed to the eating or drinking of grapefruit juice may come from a lowering of insulin level seen in people with the metabolic syndrome. High levels of insulin are linked to weight gain. Patients who ate a half a grapefruit or drank grapefruit juice with every meal lost 3.6 and 3.3 pounds, respectively. Some patients lost more than 10 pounds.
  • You can judge a fruit by its cover. Orange and tangerine peels (and not the fruit inside) interested scientists at the USDA and KGK Synergize, a Canadian nutraceutical company. They demonstrated that compounds called polymethoxylated flavones (PMFs) found in the peels of oranges reduced 'bad' LDL cholesterol levels by 32% to 40% in hamsters that had high levels of blood cholesterol. Reductions in other blood fats were also seen in the experiment.
  • Turning interactions into an advantage: Studies show that grapefruit juice can interact in a potentially dangerous way with certain medications, especially heart, blood pressure, antibiotics, and HIV antiviral medications. Grapefruit juice affects their metabolism, creating increased levels of the drug in the blood, which can have serious consequences. Texas A&M Citrus Center researchers identified three compounds in grapefruit juice that can turn off a key enzyme (CYP3A4) responsible for metabolizing drugs. The scientists envision these enzyme blockers in grapefruit-juice compounds being turned into a "super pill." When combined with many medications they can reduce the doses and costs of these drugs.
  • Grapefruit juice helps smokers lower cancer risk: Obviously, the best way for smokers to reduce their risk of cancer is to stop smoking. However, researchers at the University of Hawaii say three 6-ounce glasses of grapefruit juice a day may help smokers fight off cancer. The small controlled study of 49 smokers showed that a thrice-daily dose of grapefruit juice slowed activity of CYP1A2, a protein which helps activate the cancer-causing substances found in tobacco smoke.

Show Sources

SOURCES: "Potential Health Benefits of Citrus," 228th National Meeting of the American Chemical Society, Philadelphia, Aug. 24-25, 2004. News release, American Chemical Society.

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