DIM (Diindolylmethane)
Shifts estrogen metabolism toward the protective 2-hydroxy pathway and away from the proliferative 16-hydroxy pathway. The estrogen-balance supplement.
Strong for shifting urinary 2:16 estrogen metabolite ratios in the desired direction (well-documented). Moderate for: hormonal acne, fibrocystic breasts, mild PMS, BPH support in men. Used adjunctively in some breast cancer prevention contexts. Effects: 8–12 weeks for hormone metabolite ratios.
DIM is the active compound the stomach forms when you eat I3C (indole-3-carbinol) from cruciferous vegetables — broccoli, cauliflower, cabbage, Brussels sprouts. It modulates how the liver metabolises estrogen, favouring the 'good' 2-hydroxyestrogen (anti-proliferative, less linked to cancer risk) over the 'bad' 16-hydroxyestrogen (more proliferative). For women, this matters for managing estrogen dominance symptoms — heavy periods, PMS, fibrocystic breasts, hormonal acne. For men, DIM helps clear excess estrogen and supports a healthier testosterone-to-estrogen ratio.
- Form
- BioResponse DIM (BR-DIM) — the patented, bioavailable, well-studied form. Plain DIM — cheaper but absorbs poorly. I3C — upstream precursor; the body converts to DIM (less efficient, less consistent).
- Dose
- 100–200 mg/day BR-DIM. Up to 300 mg/day in some clinical protocols.
- Timing
- With food. AM or split AM/PM.
- Schedule
- Daily. Cycle off periodically (e.g. 3 months on, 1 off) optional.
- Side effects
- Generally well-tolerated. Headache, GI upset, darker urine (harmless). Estrogen-rebalancing effects can cause transient symptoms changes.
- Interactions
- Hormonal contraceptives, HRT — can reduce contraceptive efficacy by accelerating estrogen metabolism. Tamoxifen, aromatase inhibitors — complex interaction (discuss with oncology). CYP3A4 / CYP1A2 substrates — DIM modulates these enzymes.
- Contraindications
- Pregnancy / breastfeeding. On hormonal contraception (use additional birth control or avoid). Hormone-sensitive cancers without provider input.
- Lab markers
- Urinary 2-OH vs 16-OH estrogen ratio (DUTCH test or similar — the most informative marker for DIM users). Estradiol, estrone.
- Food sources
- Cruciferous vegetables — broccoli, broccoli sprouts, brussels sprouts, cabbage, kale, cauliflower, bok choy. Eating cruciferous regularly (3–5 servings/week) provides background DIM/I3C support; supplementation delivers therapeutic doses.
Pairs with
Calcium D-glucarate (works downstream — supports estrogen excretion). I3C (upstream precursor). Sulforaphane (additional Phase II detox support). Magnesium, B6, P5P (estrogen metabolism cofactors).
within Hormone precursors & modulators