In the November issue of Nutrition and Cancer, Italian researchers reported on a protective effect against cancer from plant compounds that include flavinoids and proanthocyanidins. Collectively known as "polyphenols" these compounds are found in fruits and vegetables, and other plants foods, including whole grains, nuts, and legumes. It's believed that the protective effect of plant foods against a wide range of chronic diseases is due largely to polyphenols.
Dr. Carlo La Vecchia and colleagues from the University of Milan evaluated data collected at multiple Italian centers since the early 1990s. The studies included a total of 9,622 cases of cancer and 16,050 controls. Based on questionaires, the participants' diets were analyzed for 6 classes of flavonoids: isoflavones, anthocyanidins, flavanols, flavanones, flavones and flavonols. Also, 6 distinct classes of proanthocyanidins were evaluated. And the results showed the following:
For those whose intake of total flavonoids was in the top one-fifth of participants, there was a 44 percent lower risk of oral cancer and a 40 percent lower risk of laryngeal cancer compared to those whose intake was in the lowest fifth. Participants whose intake of flavanones was among the top one-fifth had a 49 percent lower risk of oral cancer and a 40 percent lower risk of laryngeal cancer, and those whose flavonols were highest experienced 38 percent less oral cancer and 68 percent lower risk of laryngeal cancer. Among those whose flavanol intake was highest there was a 36 percent decrease in laryngeal cancer compared to the lowest group, and for subjects whose flavanone intake was highest, the risk of esophageal cancer was 62 percent lower.
When colorectal cancer was considered, subjects whose intake of anthocyanidins was highest had a 33 percent less risk of this disease compared to the lowest group, and for those having the highest intake of flavonols, flavones and isoflavones, there was a 36 percent, 22 percent and 24 percent lower risk respectively. Proanthocyanidins lowered the risk of colon cancer by 42 percent.
The researchers found that rates of breast, ovarian, and kidney cancers were similarly slashed by high polyphenol consumption.
Dr La Vecchia and coauthors noted that a recent Japanese investigation revealed a decreased risk of localized prostate cancer among those with the greatest intake of isoflavones- a class of nutrients with low intakes among Italians. He concluded by saying:
"The findings from this large network of Italian case-control studies have provided support for an apparent protective role of flavanones on upper aerodigestive tract cancers; flavonols, anthocyanidins, and proanthocyanidins on colorectal cancer; flavonols and flavones on breast cancer; isoflavones on ovarian cancer; and flavonols on renal cancer."
So, what foods are highest in polyphenols? Berries top the list, including all berries, and blueberries may be at the very top. Fruits in general are very high in polyphenols, particularly richly-hued fruits. Pomegranites, cherries, red grapes, and red plums are very high in polyphenols, but even apples and pears score high. Vegetables are generally lower in polyphenols than fruits, but red vegetables, such as red beets and red cabbage are exceptions.Then, nuts, beans, and whole grains are close to equal in their phenolic content. Cocoa is a legume, and it's high in polyphenols, but obviously, it takes a lot of processing to transform cocoa beans into chocolate. If you consume chocolate, you should avoid milk chocolate, and you should look for chocolate that is sweetened with fruits rather than refined sugar. However, even with that, I don't think chocolate should be eaten as a dietary staple. I think we all know, intuitively, that when we eat a plum, we are eating a natural food, but when we eat chocolate, we are eating candy.
The most important thing is to eat a wide variety of fresh fruits and vegetables every day.