Quercetin Present in Fruits, Vegetables

Scientists are discovering a new reason to eat more onions, as well as grapes, broccoli and yellow Italian squash, says Dr. Terrance Leighton, professor of biochemistry at the University of California at Berkeley.

All are rich in a compound called quercetin, which Leighton calls “one of the strongest anti-cancer agents known.”

In dozens of lab studies, quercetin has blocked initial cell changes that set the stage for cancer. More important, says Leighton, quercetin powerfully suppresses the proliferation of malignant cells that amass into a tumor.

Also, well-documented studies show that enthusiastic onion and broccoli eaters have a lower risk of certain cancers. Quercetin is a prime reason, Leighton thinks.

“It’s amazing how much quercetin an onion has,” he says. “Ten percent of the dry weight of an onion is quercetin.” But, strangely, only red and yellow onions contain quercetin--not white onions or garlic, a close cousin of the onion.

Red wine also is rich in quercetin. But that doesn’t mean drinking red wine prevents cancer. Quercetin, says Leighton, seems to merely cancel out alcohol’s cancer-promoting effects.

The good news is that you get the same lift from a cup of coffee every morning--day after day--no matter how long you’ve been drinking it or how much of it you drink.

That shows coffee doesn’t work like other addictive drugs, says Dr. Andrew Baum, professor of medical psychology at the Uniformed Services University of the Health Sciences in Bethesda, Md. “You don’t have to drink more of it to feel good.” Usually, he says, a person has to take more of a substance to get the same kick.

Baum’s research team tested 48 heavy coffee drinkers, who averaged six cups a day. One morning, they got a large mug of coffee (12 ounces) with caffeine. Another morning they got either decaffeinated coffee or caffeine-free herbal tea.

After one cup of the real coffee they had a surge in mood, were less stressed and performed better on mental tasks. When deprived of caffeine, they were grumpy, irritable, lethargic, complained of headaches and didn’t perform nearly as well.

Baum says the point is that if you have to cut back on coffee drinking for health reasons, it’s good to know that a single cup can still give you that critical morning “jump-start.”