Study: Compounds that Give Fruits and Vegetables Their Color Fight Cancer

On Aug. 19, at the national meeting of the American Chemical Society in Boston, Mass., Dr. M. Monica Giusti, an assistant professor in the Food Science and Technology Department at Ohio State University, Columbus, Ohio, presented the findings of a recent study of anthocyanins' effect on cancer cells. Very simply put, anthocyanins are pigments or compounds found in reddish or purplish fruits and vegetables, including purple cabbage, beets, blueberries, cherries, chokeberries, raspberries, bilberries, purple carrots and purple grapes.

The press release of the event states that, according to Dr. Giusti, the results of laboratory experiments on rats and on human colon cancer cells suggest that anthocyanins significantly slow the growth of colon cancer cells.

Dr. Giusti said that red, purple and blue fruits and vegetables "contain many compounds, and we're just starting to figure out what they are and which ones provide the best health benefits."

As Dr. Giusti and her team studied human colon cancer cells grown in laboratory dishes, they tested the cancer fighting effects of extracts from a variety of fruits and vegetables, including grapes, radishes, purple corn, chokeberries, bilberries, purple carrots and elderberries - all plants with extremely deep colors and, therefore, high in anthocyanins.

First, Dr. Giusti and her colleagues figured out how much extract was needed from each plant to cut the growth of human colon cancer cells in half. Different plant extracts were then added to flasks containing colon cancer cells. Using an analytical technique called high-performance liquid chromatography - mass spectrometry, they figured out precisely how each compound was chemically structured.

Although it's an overly simple explanation of the technique, suffice it to say that liquid chromatography is used to separate components of a mixture (the extracts and the colon cancer cells) by using chemical interactions. Mass spectrometry is a technique used to find the composition of the components by identifying their unknown compounds. The end result was that the researchers were able to learn the precise chemical structure of each compound. Then they were able to test and determine how many cancer cells were left after anthocyanin treatment.

What they found was that the amount of anthocyanin extract needed to reduce cancer cell growth by 50 percent varied, depending on the plant used. The most potent extract came for purple corn. Radish extract was the least potent, taking nine times more radish extract than purple corn extract to cut cancer cell growth in half. Dr. Giusti said, however, that "all fruits and vegetables that are rich in anthocyanins have compounds that can slow down the growth of colon cancer cells, whether in experiments in laboratory dishes or inside the body."

In other studies using radish and black carrot extracts, the researchers found that cancer cell growth was slowed down anywhere from 50 percent to 80 percent. Even better, however, extracts from purple corn and chokeberries completely stopped cancer cell growth and killed about 20 percent of the cancer cells themselves, while having virtually no effect on healthy cells.

Adding more promise to the research was the fact that studies of rats induced with colon cancer cells who were then fed a daily diet of anthocyanin extracts from bilberries and chokeberries had reduced signs of the colon tumors by 70 percent and 60 percent, respectively, compared to control rats.

Other Ohio State University researchers found that black raspberries may help reduce the growth of esophageal and colon cancer tumors.

Dr. Giusti said that there are over "600 different anthocyanins found in nature. While we know that the concentration of anthocyanins in the GI tract is ultimately affected by their chemical structures, we're just beginning to scratch the surface of understanding how the body absorbs and uses these different structures." She said they do know that "very little anthocyanin is absorbed by the bloodstream, but a large proportion travels through the gastrointestinal tract, where those tissues absorb the compound."

Dr. Giusti said that she and her team of researchers are also looking at how these pigments interact with other compounds in foods . Depending on the interactions, they may ultimately affect the health benefits of the food or the anthocyanin itself. What this holds for future cancer treatment and prevention is still not exactly known, but there's no doubt that consuming fruits and vegetables that are rich in color certainly cannot do anyone harm.

According to the Institute of Food Technologists (IFT), Dr. Guisti is well known for her work and is a member of IFT's Fruit and Vegetables Product Division, having a special interest in studying what is called "functional foods."

The American Chemical Society (ACS) is said to be the leading publisher of peer-reviewed research journals in the chemical and related sciences.

Sources:

Press release, Compounds that Color Fruits and Veggies May Protect Against Colon Cancer; http://www.newswise.com/articles/view/532497/

IFT; http://foodsafety.cas.psu.edu/IFT_contacts/show_ift_database2.cfm?record=167

ACS; http://pubs.acs.org/about_us.html