Newswise — An apple peel a day might help keep cancer at bay, according to Rui Hai Liu, Cornell associate professor of food science, who has identified a dozen compounds -- triterpenoids -- in apple peel that either inhibit or kill cancer cells in laboratory cultures. Three of the compounds have not previously been described in the literature.
"We found that several compounds have potent anti-proliferative activities against human liver, colon and breast cancer cells and may be partially responsible for the anti-cancer activities of whole apples," says Liu, who is affiliated with Cornell's Institute of Comparative and Environmental Toxicology and is senior author of the study, which is online and published in the Journal of Agricultural and Food Chemistry.
In previous Cornell studies, apples had been found not only to fight cancer cells in the laboratory but also to reduce the number and size of mammary tumors in rats. The Cornell researchers now think that the triterpenoids may be doing much of the anti-cancer work.
"Some compounds were more potent and acted differently against the various cancer cell lines, but they all show very potent anti-cancer activities and should be studied further," says Liu.
With co-author Xiangjiu He, a Cornell postdoctoral researcher, Liu analyzed the peel from 230 pounds of red delicious apples from the Cornell Orchard and isolated their individual compounds. After identifying the structures of the promising compounds in the peel, the researchers tested the pure compounds against cancer cell growth in the laboratory. In the past, Liu has also identified compounds called phytochemicals -- mainly flavonoids and phenolic acids -- in apples and other foods that appear to be have anti-cancer properties as well, including inhibiting tumor growth in human breast cancer cells.
"We believe that a recommendation that consumers to eat five to 12 servings of a wide variety of fruits and vegetables daily is appropriate to reduce the risks of chronic diseases, including cancer, and to meet nutrient requirements for optimum health," said Liu.
Additional recent researches have shown that eating apples are linked to reducing cancer risk in several studies. Some examples are:
* Quercetin, a flavonoid abundant in apples has been found to help prevent the growth of prostate cancer cells.
* Phytonutrients in the skin of apples inhibited the growth of colon cancer cells by 43% .
* Food containing flavonoids like those in apples may reduce risk of lung cancer as much as 50% .
* Dietary phenolics such as flavonoids (found in apples) have inhibitory effects on the developments of carcinogenic substances in the bladder, thereby reducing risk of bladder cancer, especially in smokers.
Also, eating apples could improve lung function and reduce the risk of respiratory diseases such as chronic obstructive pulmonary disease (COPD) due to antioxidants present in apples that would counter the oxygen's damaging effects on the body as well as the flavonoids such as catechins (present in apples and tea).
In addition, studies have shown that a diet rich in apples could help to lower the blood cholesterol level. Pectin, a soluble fiber found in apples has been thought to play a significant role in this. In fact, apple juice has been found to inhibit the oxidation of a harmful form of cholesterol (LDL, or low-density lipoprotein).
Besides therapeutic benefits, apples are also found to play a role in inhibiting ageing-related problems, preventing wrinkles and promoting hair growth (due to a compound named procyanidin B-2).
For those weight-watchers, this is good news as apples are a delicious source of dietary fiber and helps to aid digestion and promote weight loss.
My recommendation is that if you are going to eat apple peels, make sure your apples are organic.