Flavonoids and Protection from Cancer: Enhancement of DHEA? Copyright 2004, James Michael Howard, Fayetteville, Arkansas, U.S.A. It is my hypothesis that low dehydroepiandrosterone (DHEA) may trigger cancer. Therefore, when the background source of DHEA in the blood, DHEAsulfate, is high at the expense of being desulfonated into the active form, DHEA, the incidence of cancer may increase. It is known that "flavonoids" protect against cancer. I suggest this is the result of flavonoids inhibiting the formation of DHEAsulfate from DHEA. In other words, flavonoids may protect against cancer by helping to maintain the levels of DHEA, that is, flavonoids help maintain a higher DHEA to DHEAsulfate ratio. (Please read the abstract below.) I invite you to read my explanation of the connection of DHEA with cancer at www.anthropogeny.com/research.html ; look for "How 'Hormone Replacement Therapy' (HRT) May Cause Breast Cancer." "Inhibition of rat liver sulfotransferases SULT1A1 and SULT2A1 and glucuronosyltransferase by dietary flavonoids." Mesia-Vela S, Kauffman FC. "1. Dietary flavonoids including kaempferol, quercetin, genistein and daidzein were tested for their ability to alter the conjugation of oestradiol (E(2)) via rat liver sulfotransferases and glucuronosyltransferase. 2. All four flavonoids inhibited the sulfonation of E(2) via phenol sulfotransferase, SULT1A1 with IC(50)s ranging from 0.29 to 4.61 micro M. Sulfonation of dehydroisoandrosterone (DHEA) via hydroxysteroid sulfotransferase, SULT2A1, was inhibited by higher amounts of the flavonoids (IC(50)s ranging from 34 to 116 micro M). 3. All flavonoids inhibited the formation of E(2)-beta- glucuronides (at carbon atoms 3 and 17) with IC(50)s ranging from 43 to 260 micro M. Glucuronidation of 4-methylumbelliferone (4-MU) was inhibited by high amounts of the flavonoids (IC(51)s ranging from 860 to 1550 micro M). 4. Hydrolysis of sulfonated oestrogens via arylsulfatase- c (ARSC) or 4-methylumbelliferone beta-glucuronidate (MUG) were not inhibited by the flavonoids. 5. It is concluded that SULT1A1 but not SULT2A1 or glucuronosyltransferase is highly sensitive to inhibition by dietary flavonoids. The potency of the inhibition for SULT1A1 (quercetin > kaempferol > genistein > daidzein) suggests a dependency on the number and position of hydroxyl radicals in the flavonoid molecule." Xenobiotica. 2003 Dec; 33(12): 1211-20.