A Canary's Eye View — Metabolic Basis
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Metabolic Basis
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Endogenous Estrogens (produced in the body):

Estradiol [get info]

Estrone [get more info]

  • Breakdown metabolism:
    • 16 alpha-Hydroxyestrone (from C-16 hydroxylation)
      • ...is genotoxic, promoting unscheduled DNA synthesis and hyperproliferation (cancer).
      • As a result, 16a-H is often called "bad" estrogen. However, my gynecologist, who does a lot of study, says recent research links it with lowered osteoporosis. I have not found references for this yet.
    • 2-Hydroxyestrone (from C-2 hydroxylation.) is associated with a decreased risk of endometrial cancer. Often called the "good" estrogen.
    • (For changing the ratio of estrone metabolites, see Estrogen modifiers.)
  • Catechol estrogens — 2-hydroxyestrone and 4-hydroxyestrone — are carcinogenic. However they also have the very beneficial effect of inhibiting
    • E2 inflammatory prostaglandins
    • synthesis of pain-producing leukotrienes
  • Premarin is 50% estrone sulfate. Another 25% is equilin and 15% is equilenin: horse estrogens that do not naturally occur in human metabolism. For a discussion of the properties of these hormones, see Premarin—Facts & Opinions, on the site of Project Aware.

Estriol [get more info]

How the body produces estrogens

Phytoestrogens, plant-source estrogen-mimics

      • Soy isoflavones and flax lignans improve 2/16 ratio.
      • "The main phytoestrogen in hops, 8-Prenylnaringenin, competed strongly with 17ss-estradiol for binding to both the alpha- and ss-estrogen receptors." From Hops and Lupulin, at the Flora Herb & Supplement Encycopedia. The study mentioned is probably Milligan SR, Kalita JC, Pocock V, Van De Kauter V, Stevens JF, Deinzer ML, Rong H, De Keukeleire D. 2000. The endocrine activities of 8-prenylnaringenin and related hop (Humulus lupulus L.) flavonoids. J Clin Endocrinol Metab. 2000 Dec; 85(12): 4912-5. (References are not identified in the text of Flora web page, just listed at the end.)

Other xenoestrogens, chemicals that act as estrogens in the body (phytoestrogens are also xenoestrogens)

For more information

Last updated 5 September 2005