Lemons - lemons and limes contain unique flavonoid compounds that have antioxidant and anti-cancer properties. Of special interest in limes have been flavonoids called flavonol glycosides, including many kaempferol-related molecules. While these flavonoids have been shown to stop cell division in many cancer cell lines, they are perhaps most interesting for their antibiotic effects. In several villages in West Africa where cholera epidemics had occurred, the inclusion of lime juice during the main meal of the day was determined to have been protective against the contraction of cholera. (Cholera is a disease triggered by activity of the bacteria called Vibrio cholera). Researchers quickly began to experiment with the addition of lime juice to the sauce eaten with rice, and in this role, lime juice was also found to have a strong protective effect against cholera.

Several other fascinating research studies on the healing properties of lemons and limes have shown that cell cycles—including the decision a cell makes about whether to divide (called mitosis) or die (apoptosis—are altered by lime juice, as are the activities of special immune cells called monocytes.

In addition to their unique phytonutrient properties, lemons and limes are an excellent source of vitamin C, one of the most important antioxidants in nature. Vitamin C is one of the main antioxidants found in food and the primary water-soluble antioxidant in the body. Vitamin C travels through the body neutralizing any free radicals with which it comes into contact in the aqueous environments in the body both inside and outside cells. Free radicals can interact with the healthy cells of the body, damaging them and their membranes, and also cause a lot of inflammation, or painful swelling, in the body. This is one of the reasons that vitamin C has been shown to be helpful for reducing some of the symptoms of osteoarthritis and rheumatoid arthritis.

Since free radicals can damage blood vessels and can change cholesterol to make it more likely to build up in artery walls, vitamin C can be helpful for preventing the development and progression of atherosclerosis and diabetic heart disease.

Vitamin C is also vital to the function of a strong immune system. The immune system's main goal is to protect you from illness, so a little extra vitamin C may be useful in conditions like colds, flus, and recurrent ear infections.

Owing to the multitude of vitamin C's health benefits, it is not surprising that research has shown that consumption of vegetables and fruits high in this nutrient is associated with a reduced risk of death from all causes including heart disease, stroke and cancer.

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

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

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

Limonin's bioavailability and persistence may help explain why citrus limonoids are potent anti-carcinogens that may prevent cancerous cells from proliferating. Other natural anti-carcinogens are available for much less time; for example, the phenols in green tea and chocolate remain active in the body for just 4 to 6 hours.