Quercetin: Hidden Treasure in Your Latkes

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One of my favorite winter dishes is featured in Holiday Recipes from AICR’s Test Kitchen: Low Fat Latkes.

When served with applesauce, the three key ingredients in this dish—potatoes, onions, and apples—each contain large quantities of a phytochemical called quercetin. 

Quercetin is classified as a flavonoid.  Lab studies suggest quercetin may offer protection from many chronic diseases such as cancer.

In a well-cited 1997 study, scientists gave volunteers apples and onions and then measured the amount of quercetin in their blood and urine. The nine volunteers ate apples, had their urine/blood checked and then five days later repeated the process with the onions.

They discovered that about half of the quercetin in apples and onions remained in the bloodstream from 23 to 28 hours, respectively.  But the peak concentration of an onion’s quercetin was detected in the blood in as little as 45 minutes! Trace amounts of quercetin could still be detected 36 hours after eating the onions and apples.

This means the health benefits of quercetin can be experienced within minutes of eating and may last for a full day or more.

The reason for this all-day protection is that quercetin, like many phytochemicals, is fat-soluble.  In order for quercetin to enter the bloodstream, special proteins in the small intestine must attach water-soluble molecules to it.

About half of the quercetin heads to the liver.  Then it enters the blood and gets carried to the body’s tissues where it delivers its many health benefits.  Some of the quercetin stays in the intestine and provides its health benefits to the colon.  One way or another, eventually the quercetin is eliminated by the body.  This is a long process!

Eating a varied diet that includes not only apples, onions, and potatoes but also many other phytochemical-rich foods allows your body’s cells to be bathed in these beneficial compounds daily.



    Author: Teresa

    Teresa L. Johnson, MSPH, RDN, is a nutrition and health communications consultant with a long-time interest in the role of plant-based diets and cancer prevention. Her work draws on elements of nutritional biochemistry, phytochemistry, toxicology, and epidemiology.

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