Oestrogen Dominance.
When Balance Is Off.

Cortisol competes with progesterone at its receptor — chronically elevated cortisol effectively blocks progesterone's action, creating relative oestrogen dominance even when oestrogen is normal.

Progesterone is the first hormone to significantly decline in perimenopause — creating years of relative oestrogen dominance before oestrogen itself falls.

Adipose tissue contains aromatase, which converts androgens to oestrone (E1). More body fat = more peripheral oestrogen production, independent of the ovaries.

The liver is responsible for metabolising and clearing used oestrogens. Impaired liver detoxification (alcohol, fatty liver, nutrient deficiencies) leads to oestrogen recirculation.

Certain gut bacteria produce beta-glucuronidase, which deconjugates cleared oestrogens and allows them to re-enter circulation. Poor gut health amplifies oestrogen load.

Oestrogen-mimicking chemicals found in BPA plastics, pesticides, parabens in personal care products and certain medications act as environmental oestrogens.

When ovulation doesn't occur, no corpus luteum forms and no progesterone is produced — leaving oestrogen unopposed in the luteal phase.

A progesterone-to-oestradiol ratio below 100:1 (conventional units) may indicate relative dominance. Absolute levels matter less than ratio.

Low SHBG increases free oestrogen availability. High SHBG (common on the OCP) lowers free testosterone but may not protect against oestrogen dominance.

Reveals oestrogen metabolism pathways — whether oestrogens move through the protective 2-OH pathway or the more proliferative 16-OH and 4-OH pathways. Critical for cancer risk assessment and treatment direction.

Thyroid dysfunction co-exists with and worsens oestrogen dominance — always screen TSH, Free T4, Free T3 and TPO antibodies.

Cruciferous vegetables (broccoli, cauliflower, kale) provide DIM and sulforaphane — potent promoters of the 2-OH oestrogen metabolite pathway. DIM supplements (200–400mg/day) are a targeted option.

Regular bowel movements are essential — oestrogen is excreted in stool. Fibre, probiotics (Lactobacillus), and addressing dysbiosis reduce enterohepatic oestrogen recirculation.

Choose glass over plastic, buy organic where possible, switch to natural personal care products without parabens and phthalates. Impractical to eliminate entirely, but every reduction helps.

Cortisol management is as important as oestrogen management. Sleep, HRV-based stress practices, adaptogens and exercise moderation directly improve progesterone-to-oestrogen ratio.

Where progesterone is confirmed low (day 21 <30 nmol/L), Utrogestan (micronised progesterone) restores balance effectively. Prescribed and monitored by a qualified practitioner.

Reducing excess adipose tissue reduces peripheral aromatisation. Even a 5–10% weight reduction significantly improves the oestrogen-to-progesterone ratio.