Health Benefits

Rich in the Nutritional Powerhouse Vitamin C

Enjoy Benefits from the Antioxidant Lycopene

Limonoids Promote Optimal Health

Phytonutrients in grapefruit called limonoids inhibit tumorformation by promoting the formation of glutathione-S-transferase, adetoxifying enzyme. This enzyme sparks a reaction in the liver thathelps to make toxic compounds more water soluble for excretion from thebody. Pulp of citrus fruits like grapefruit contain glucarates,compounds that may help prevent breast cancer.

In animal studies and laboratory tests with human cells,limonoids have been shown to help fight cancers of the mouth, skin,lung, breast, stomach and colon. Now, scientists from the USAgricultural Research Service (ARS) have shown that our bodies canreadily absorb and utilize a very long-acting limonoid called limoninthat is present is citrus fruits in about the same amount as vitamin C.

In citrus fruits, limonin is present in the form of limoninglucoside, in which limonin is attached to a sugar (glucose) molecule.Our bodies easily digest this compound, cleaving off the sugar andreleasing limonin.

In the ARS study, 16 volunteers were given a dose of limoninglucoside in amounts ranging from those that would be found in from 1to 7 glasses of orange juice. Blood tests showed that limonin waspresent in the plasma of all except one of the subjects, withconcentrations highest within 6 hours after consumption. Traces oflimonin were still present in 5 of the volunteers 24 hours afterconsumption!

Limonin's bioavailability and persistence may help explain whycitrus limonoids are potent anti-carcinogens that may prevent cancerouscells from proliferating. Other natural anti-carcinogens are availablefor much less time; for example, the phenols in green tea and chocolateremain active in the body for just 4 to 6 hours.The ARS team is now investigating the potential cholesterol-loweringeffects of limonin. Lab tests indicate that human liver cells produceless apo B when exposed to limonin. Apo B is a structural protein thatis part of the LDL cholesterol molecule and is needed for LDLproduction, transport and binding, so higher levels of apo B translateto higher levels of LDL cholesterol.

Grapefruit Lowers Cholesterol

Grapefruit contains pectin, a form of soluble fiber that has beenshown in animal studies to slow down the progression ofatherosclerosis. In one study, animals fed a high-cholesterol diet plusgrapefruit pectin had 24% narrowing of their arteries, while animalsfed the high-cholesterol diet without grapefruit pectin had 45%narrowing.

Both blond and red grapefruit can reduce blood levels of LDL("bad") cholesterol, and red grapefruit lowers triglycerides as well,shows a study published in the Journal of Agricultural and Food Chemistry.

Israeli researchers from the Hebrew University in Jerusalemfirst tested the antioxidant potential of blond and red grapefruits andthen their cholesterol-lowering potential in humans. The test tuberesearch showed that red grapefruit contains more bioactive compoundsand total polyphenols than blond, but both grapefruits are comparablein their content of fiber, phenolic and ascorbic acids, and theflavonoid, naringinen, although red grapefruit contains slightly moreflavonoids and anthocyanins.

In this recent study, participants added either red grapefruit,blond grapefruit or no grapefruit to their daily diet. The resultsindicated that both types of grapefruit appeared to lower LDLcholesterol in just 30 days: total cholesterol by 15.5% in those eatingred grapefruit and 7.6% in those eating blond grapefruit; LDLcholesterol by 20.3% and 10.7% respectively; and triglycerides by 17.2%and 5.6% respectively. No changes were seen in the control group (thosethat didn't eat any grapefruit).

Both red and blond grapefruits both positively influencedcholesterol levels, but red grapefruit was more than twice aseffective, especially in lowering triglycerides. In addition, bothgrapefruits significantly improved blood levels of protectiveantioxidants. Red grapefruit's better performance may be due to an asyet unknown antioxidant compound or the synergistic effects of itsphytonutrients, including lycopene.

In response to this rapid and very positive outcome, theresearchers concluded that adding fresh red grapefruit to the dietcould be beneficial for persons with high cholesterol, especially thosewho also have high triglycerides.One caveat, however: Compounds in grapefruit are known to increasecirculating levels of several prescription drugs including statins. Forthis reason, the risk of muscle toxicity associated with statins mayincrease when grapefruit is consumed. (See our Safety section for moreinformation.)

Prevent Kidney Stones

Promotes Optimal Health

Not only are grapefruit rich in vitamin C, but new researchpresented at the 228th National Meeting of the American ChemicalSociety provides two more reasons to drink grapefruit juice: protectionagainst lung and colon cancer.

In humans, drinking three 6-ounce glasses of grapefruit juice aday was shown to reduce the activity of an enzyme that activatescancer-causing chemicals found in tobacco smoke. In rats whose colonswere injected with carcinogens, grapefruit and its isolated activecompounds (apigenin, hesperidin, limonin, naringin, naringenin,nobiletin) not only increased the suicide (apoptosis) of cancer cells,but also the production of normal colon cells.Researchers also confirmed that grapefruit may help prevent weight gainby lowering insulin levels.

Grapefruit Boosts Liver Enzymes that Clear Out Carcinogens

Grapefruit juice significantly increases the production and activityof liver detoxification enzymes responsible for preparing toxiccompounds for elimination from the body.

The liver clears out toxins, including carcinogens, using a twostep process called Phase I and Phase II detoxification. In the firstpart of this process, Phase I, enzymes belonging to the cytochrome P450family, work on the toxin to make it more attractive to enzymesinvolved in the second part of the process, Phase II. Unfortunately,the action of Phase I enzymes often renders the toxin not only moreattractive to Phase II enzymes, but even more dangerous, and some foodscontain compounds that only increase the activity of Phase I withoutalso turning up Phase II.

Grapefruit increases the activity not only of the Phase Ienzyme CYP1A1, but also that of NAD(P)H:quinone reductase 1, a Phase IIdetoxification enzyme that protects cells against oxidative stress andtoxic quinones.The end result: grapefruit works in both Phase I and Phase II toenhance the liver's ability to remove cancer-causing toxins.

Grapefruit's Naringenin Repairs DNA

Naringenin, a flavonoid concentrated in grapefruit, helps repairdamaged DNA in human prostate cancer cells (cell line LNCaP), reports alab study published in the Journal of Nutritional Biochemistry.

The risk of prostate cancer, the most commonly diagnosed cancerin men in the U.S, increases with age since the older we become, themore times our cells have divided and the greater the chance for DNAmutations to occur. DNA repair is one of the body's primary defensemechanisms against the development of cancer since it removespotentially cancer-causing mutations in cells.

Naringenin helps restore health to damaged DNA by inducing twoenzymes that repair DNA during the replication stage. These enzymes,8-oxoguanine-DNA glycosylase 1 (hOGG1), and DNA polymerase beta (DNApoly beta), are both involved in the DNA base excision repair (BER)pathway.

The scientists in this study exposed cell cultures to 80micromoles per liter, an amount we cannot achieve by consuminggrapefruit since research indicates that only between 2 and 15%flavonoids in the food we consume are absorbed in the GI tract, andplasma concentrations after eating flavonoid-rich foods range from 0.5to 1 micromole per liter.