Oestrogen Metabolism Part 1: Understanding the Basics

OESTROGEN is a broad term for the group of female hormones.

The most potent of these hormones is estradiol.  Two less powerful yet equally important ones include estrone and estriol.

Function of Oestrogens

Oestrogens have a wide range of actions and affect all systems in the body. They play a role in women:

  • Growth and function of body tissues (including those involved in the reproductive process, as well as other tissues throughout the body).
  • Bone health
  • Heart health
  • Influencing behaviour and mood

They also play a role in men:

  • Male tissues (prostate and testes)

In woman, the ovaries produce cholesterol which is broken down to oestrogens.

Adult women with normal menstrual cycles secrete 70-500mcg estradiol/day from their ovarian follicles, depending on the phase of the menstrual cycle. This estradiol is used, metabolised and it’s end product is excreted in the urine.

Oestrogens are also produced in smaller amounts in fat cells, skin, bone and other tissues.

After menopause most oestrogen in the body is produced in the peripheral tissues of the body. In addition some oestrogen continues to be manufactured in body fat. The ovaries also continue to produce small amounts of testosterone which is converted to estradiol. Yet the total oestrogen produced after menopause is far less than that produced during a woman’s reproductive years.

Oestrogens circulate in the body bound mainly to the sex hormone binding globulin (SHBG). If levels of SHBG drop then some oestrogens are unbound. This unbound oestrogen results in increased oestrogen exposure, and can enter certain tissues in the body, causing tissue changes and potential damage (e.g. endometriosis, PMS and, in extreme cases breast / ovarian cancers).

The ultimate effect of oestrogen depends on how it is metabolised.

Dietary factors can increase SHBG in the body, thus improving oestrogen metabolism and minimising the potential damage caused by excessive oestrogen exposure.


Lifestyle factors that increase the body’s production of oestrogen:

  • Obesity (causes an increased oestrogen production in fat tissue, and thus increased oestrogen exposure)
  • Excess insulin in the blood stream (prompts the ovaries to secrete excess testosterone and reduces SBHG levels, thus increasing levels of free oestrogen)
  • Alcohol consumption (increases oestrogen levels)

Other factors increasing oestrogen production:

  • Oral Contraceptives and HRT (your doctor / specialist will be checking you for unbalanced levels of oestrogens, and will manage your medications accordingly)
  • Environmental toxins (e.g. certain pesticides, which structurally similar to oestrogens and can mimic harmful oestrogens in the body)

The GOOD NEWS is that DIETARY changes and addition of specific nutritional supplements CAN benefit oestrogen metabolism.

The promotion of healthy oestrogen metabolism in this way has profound significance for diseases and conditions in which these oestrogen hormones play a role.

The research shows that:

By incorporating dietary changes and using select supplements and functional foods can have profound effects in beneficially influencing oestrogen balance and thus preventing oestrogen-related diseases and conditions.


  1. Manage weight (reducing weight when overweight reduces the production of unbound oestrogen in fat cells, thus facilitating more desirable oestrogen metabolism and excretion).
  2. Reduce fat and increase fibre in the daily diet in order to influence oestrogen metabolism positively.
  3. Increase intake of cruciferous vegetables such as broccoli and cabbage to reduce excess oestrogen exposure.
  4. **Increase intake of phytoestrogen-rich (plant-compounds that improve oestrogen metabolism) foods such as SOY to reduce excess oestrogen exposure, thus reducing the risk of developing breast cancer, amongst other things.
  5. Choose complex carbohydrates (wholegrains, fruits and vegetables) over refined carbohydrates to improve stable blood glucose and thus insulin levels, reducing the negative effects of increased insulin on oestrogen balance.
  6. Use plenty of omega 3 oils to improve oestrogen metabolism.
  7. Ensure adequate but not excessive use of LEAN protein foods (lean meat and chicken, plenty of fish, low fat dairy, eggs, nuts).
  8. Vitamin E (increased levels reduce levels of unbound oestrogen; improves PMS; inhibits growth of breast cancer cells)
  9. Magnesium (improves oestrogen metabolism; promotes oestrogen detoxification;reduces PMS symptoms)
  10. Indole-3-Carbinol (I3C) – occurs naturally in cruciferous vegetables; breaks down oestrogen in a healthy manner; protective to oestrogen-sensitive tissues.
  11. B Vitamins (decreased levels of B Vitamins can disrupt oestrogen detoxification and thus increase levels of circulating estrogens; cancer protective).
  12. Other beneficial Phytonutrients
  • Curcumin (turmeric) and soya isoflavones can reduce levels of unbound oestrogen in the body.
  • Antioxidant nutrients (vitamins E and C, and selenium) can reduce the production of harmful oestrogen metabolites.
  • D-limonene (found in the oils of citrus fruit): promotes the detoxification of oestrogen.


Phytoestrogens are plant compounds that can improve oestrogen metabolism through a variety of mechanisms, and are currently being extensively investigated as a potential alternative therapy for a range of conditions associated with oestrogen imbalance (including menopausal symptoms, PMS, endometriosis, prevention of breast and prostate cancer, and protection against cardiovascular disease and osteoporosis).

There are 2 types of phytoestrogens: ISOFLAVONES and LIGNANS.

1. Isoflavones

Found in Soy (most common food source of isoflavones), legumes, alfalfa, clover, licorice root and kudzu root.

Higher intakes of soy isoflavones (as is found in traditional Japanese diets) is associated with low rates of hormone-dependant cancers.    THE AVERAGE DAILY ISOFLAVONE INTAKE OF JAPANESE WOMEN is 20-80mg; WHILE THAT OF AMERICAN WOMEN is  1-3mg.

Soy Isoflavones are antioxidants, and are the active components in the soy bean accounting for +/- 75% of the beneficial effects of soy-based foods in human health.


  • Women given 45mg soya isoflavones/day for 1 month had longer menstrual cycles.
  • Young women: given 1l soymilk/day had longer menstrual cycles, and also lower (unbound) oestrogen levels: persisting for 2-6months AFTER discontinuation of the soymilk.
  • In women with low SHBG levels: 69mg of isoflavones/day obtained from soymilk powder increased their SHBG concentrations, thus improving oestrogen metabolism.

Soy isoflavones have 3 important functions:

  1. When oestrogen levels are high in the body, isoflavones block the more potent forms of oestrogen produced by the body. In this way they may help to prevent hormone-driven diseases, such as breast and prostate cancer.
  2. When oestrogen levels are low in the body, as they are after menopause, isoflavones substitute for the body’s own oestrogen. Adequate oestrogen can possibly reduce hot flushes; and may also assist in increasing bone mineral density, thus preventing osteoporosis in post-menopausal women.
  3. These isoflavones / plant sterols have proven cholesterol-lowering effects. In this way they assist in the prevention of hyperlipidaemias, and cardiovascular disease.
  4. Soya isoflavones have also been shown to be beneficial in lowering blood pressure in those with hypertension, but not in normotensive subjects (meta-analysis 2012)

Most experts say that one should obtain the soy isoflavones required from food (not capsules).

1-2 servings a day will most likely provide adequate soya isoflavones:

1 serving = 1 cup soya milk OR ½ cup (50g) soya porridge..

2. Lignans

  • Found in fibre-rich foods and, through intestinal fermentation is converted into lignans with excellent health effects in the body.
  • Lignans are found in flaxseed, other oil seeds, wholegrains, legumes including soya and vegetables.
  • They stimulate the production of SHBG in the liver thus reducing levels of free estrogen circulation.
  • They directly decrease the conversion of testosterone to oestrogens in fat and breast cells.

CHOOSE FROM THE SOYA LIFE RANGE: obtain your DAILY DOSE OF ISOFLAVONES AND LIGNANS and improve oestrogen metabolism in the body!

  1. Soya Life Soya Milk
  2. Soya Life Meal Replacement Shake
  3. Soya Life Breakfast Porridge
  4. Soya Life Premium Porridge
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