Citrus, the most important ones are: oranges, lime, lemons and grapefruits. Their seeds are contained in segmented sections of juicy pulp called carpels and they are surrounded and protected by a resistant cover or peel.
These fruits are rich in Vitamin C, particularly the white coat underneath the peel; organge juice only contains about 20 or 30 percent of the Vitamin C that is present in the fruit and this percentage is lower in grapefruit juice.
Citrus also contain a large amount of water, citric acid and saccharose (a type of sugar).
Maybe the most important components in citrus are flavonoids and limonoids, these are not only responsible for the smell of the citrus juice, but they are also responsible for the pharmacological activity.
Citrus mostly have four types of flavonoids: flavanones, flavones, flavonols and anthocyanins; they are all strong antioxidants; they also present antibacterial, antifungal and antiviral activities.
There has been found specific data that demonstrates that certain flavonoids in citrus may have an anticarcinogetic activity. Besides that, since citrus contain ascorbic acid which is an important antioxidant, studies have shown that this combination in citrus has a better activity against carcinomas. Other flavonoids have even shown activity against metastasis since they affect the adherence of tumor cells to different organs.
Limonoids are related to the inhibition of tumorigenesis (formation of tumors) in the gastric tract, lungs and skin.
Citrus also have pectin and fiber and they are one of the best sources. It is believed that the ingestion of pectin in our diets may reduce levels of cholesterol; and pectin may also reduce the absorption of glucose (which reduces de production of insulin in blood) therefore individuals with diabetes mellitus noninsulin dependent may be treated with diet.
Pectin also helps us by reducing the risk of cardiovascular diseases by decreasing cholesterol levels especially low density lipoproteins (LDL) without decreasing high density lipoproteins (HDL) known as “the good cholesterol”.
Now, as we talked in our “Balanced Diet” article, Vitamin C can play an essential roll against scurvy, and all citrus contain important quantities of Vitamin C, and this vitamin is most abundantly contained the fruit´s pulp, ten times as much as the quantity contained in the fruit´s juice. Vitamin C is also known for its possible activity in illness prevention, not only the flu, but also helps preventing the formation of carcinogens.
The consumption of fruits with high concentrations of Vitamin C is associated with the reduction of risk of cancer of the esophagus, stomach and cervix.
Resources: Functional Foods: Biochemical and Processing Aspects