Grapefruits are a great source of phytonutrients that have been shown in studies to have anti-cancer properties. Phytonutrients are basically antioxidants that don’t fit in the regular categories of vitamins and mineral, but still have health promoting qualities. As antioxidants they protect our cells from the damaging effects of harmful oxygen molecules called free radicals. When there are more of these free radicals in our cells then the antioxidants of our immune system can handle, we are suffering from a condition known as oxidative stress.
Limonoids
Grapefruits are a great source of phytonutrients called limonoids. When we eat grapefruits, these limonoids help inhibit the growth of tumors by increasing the production of a powerful detoxifying enzyme called glutathione-S-transferase. This enzyme acts as a catalyst for the liver’s ability to break down carcinogenic toxic compounds into a safer water soluble form that can be excreted through the urine.
Drinking grapefruit juice in particular, appears to be a great way to achieve a dense concentration of these limonoids. The juice more so than the fruit has been found extremely effective at propelling the liver into producing a variety of detoxifying enzymes that break down toxic chemicals and carcinogens. A fresh homemade grapefruit juicer recipe is also more effective than a commercial grapefruit juice.
In animal studies and test tube studies using human cells, limonoids have been found very effective at fighting cancers of the skin, breast, stomach, colon and mouth. Actual human studies are still pending, but there is promise.
One major problem with test tube studies is that bio-availability of a substance cannot be assessed. In other words although an antioxidant might work great in at fighting cancer in a test tube, it will not be effective in humans if the antioxidant is not absorbed well into the blood stream during digestion. For example, the flavonoids in apples are extremely powerful anti-cancer agents in the test-tube but a negligible amount of them make it into the bloodstream when we eat apples – so their bio-availability is very poor. However, this not the case with a specific limonoid called limonin. Research shows that limonin is impressively bio-available.
Researchers from the US Agricultural Research Service gave 16 volunteers limonin in amounts similar to what you would find in 1 – 7 glasses of orange juice. The results found that limonin made into the blood stream of all but one of the volunteers. The highest blood concentration of limonin were found within 6 hours of of consumption. Even more amazingly, 5 of the volunteers still had traces of limonin in their blood 24 hours later!