Heavy Periods: Root Causes & What Actually Helps

Heavy periods are one of the most common reasons women come to me — and one of the most consistently dismissed by conventional medicine. The number of women I've spoken to who have been told "some women just bleed more" or handed a prescription for the pill without any investigation of why they're flooding through protection, passing fist-sized clots, or feeling so wiped out after their period that they need days to recover is significant. Too many.

Heavy menstrual bleeding — clinically known as menorrhagia — is not a personality trait or a genetic destiny. It is a symptom. And like all symptoms, it has causes. Some of those causes are structural (fibroids, polyps, adenomyosis); some are hormonal (estrogen dominance, low progesterone, thyroid dysfunction); some are haematological (clotting disorders). Often it's a combination. But in almost every case, there is a reason — and once you understand it, you have real options for change.

This article covers what's driving heavy periods, what the cascade of consequences looks like (including the iron deficiency that so many women with heavy periods are quietly living with), and where to start addressing the root cause rather than simply managing the bleeding.

What Counts as Heavy

Clinically, heavy menstrual bleeding is defined as losing more than 80 mL of blood per cycle. That number is rarely measured directly — but it translates into practical markers that are easier to identify:

• •Soaking through a full pad or tampon in under two hours, for several consecutive hours
• •Needing to use double protection (tampon and pad together) to prevent flooding
• •Passing blood clots larger than a 50-cent coin
• •Bleeding that lasts more than 7 days
• •Bleeding that disrupts work, exercise, social activities, or sleep
• •Experiencing significant fatigue, breathlessness, or pallor around your period — signs that iron stores may be depleted

You don't need to hit every marker on this list. If your period is significantly impacting your quality of life or leaving you exhausted, that is reason enough to investigate.

The Most Common Causes

Uterine fibroids

Fibroids are benign (non-cancerous) muscular growths that develop in or on the wall of the uterus. They are extraordinarily common — affecting up to 70–80% of women by age 50 — and are the most frequent structural cause of heavy periods. Not all fibroids cause symptoms; their impact on bleeding depends heavily on their size and location. Submucosal fibroids — those that protrude into the uterine cavity — are the most likely to cause heavy, prolonged bleeding and large clots, because they distort the uterine lining and impair the uterine contractions that normally control blood loss.

Fibroids are strongly oestrogen-sensitive, which is why they typically appear during reproductive years, grow in the presence of estrogen dominance, and often shrink after menopause. Addressing the underlying hormonal environment — particularly estrogen dominance — is an important part of any fibroid management strategy.

Uterine polyps

Polyps are soft, fleshy growths that arise from the endometrial lining (the inner lining of the uterus). They vary from a few millimetres to several centimetres in size. Endometrial polyps can cause heavy periods, bleeding between periods, and spotting before menstruation. Like fibroids, they are oestrogen-driven and associated with estrogen dominance. They are typically diagnosed via ultrasound or hysteroscopy. Removal is usually straightforward and significantly reduces associated bleeding.

Adenomyosis

Adenomyosis is a condition in which endometrial tissue — the cells that normally line the uterine cavity — grows into the muscular wall of the uterus itself. This causes the uterine wall to thicken and the uterus to enlarge (often described as a "boggy" uterus on examination). Adenomyosis is a significant cause of both heavy periods and severe menstrual cramping, as the embedded endometrial cells bleed into the muscular tissue during menstruation, causing diffuse pain and heavy flow.

Adenomyosis is frequently underdiagnosed. It can co-exist with endometriosis and fibroids, and its diagnosis typically requires specialist imaging (MRI or high-resolution ultrasound) or — definitively — histological analysis of the uterine wall. Like fibroids and polyps, it is oestrogen-sensitive.

Thyroid dysfunction

Hypothyroidism — an underactive thyroid — is a less commonly discussed but significant contributor to heavy periods. Thyroid hormones are required for the synthesis of multiple clotting factors; when thyroid function is low, clotting is impaired and bleeding becomes heavier and harder to stop. Hypothyroidism also contributes to anovulation, which means low progesterone, which further worsens estrogen dominance. Women with unexplained heavy periods who also have symptoms of hypothyroidism — fatigue, cold sensitivity, hair loss, constipation, brain fog — should have a comprehensive thyroid panel as part of their investigation.

Von Willebrand disease and other clotting disorders

Von Willebrand disease (VWD) is the most common inherited bleeding disorder, affecting approximately 1–2% of the population. It involves a deficiency or dysfunction of von Willebrand factor, a protein critical to the blood clotting cascade. Heavy menstrual bleeding — sometimes from the very first period — is frequently the primary or only symptom in women with VWD. Research suggests that a significant proportion of women with unexplained menorrhagia who have been unsuccessfully treated for other causes may have an undiagnosed clotting disorder. This is particularly worth investigating if you have a personal or family history of easy bruising, nosebleeds, or prolonged bleeding after cuts or procedures.

The Hormone Picture

Estrogen and the uterine lining

Estrogen is the growth hormone of the uterine lining. In the first half of the cycle — the follicular phase — rising estrogen drives the proliferation of the endometrium, building it up from its thin post-menstrual state into a thick, vascularised lining ready for potential implantation. This is normal and necessary.

When estrogen is elevated — due to poor clearance, excess production, or relative dominance over progesterone — the endometrium builds up more than it should. The lining becomes thicker, more vascular, and more prostaglandin-rich. When it sheds at menstruation, the result is heavier, longer, more clotted, and often more painful bleeding.

Progesterone and its moderating role

Progesterone, produced after ovulation, normally moderates estrogen's proliferative effect on the uterine lining. It matures and stabilises the endometrium, prevents excessive growth, and regulates prostaglandin production — reducing the inflammatory signalling that drives cramping and heavy flow. When progesterone is insufficient in the luteal phase (due to anovulation, a weak corpus luteum, or stress-driven depletion), estrogen goes relatively unopposed, and the endometrium can become pathologically thickened.

This estrogen-progesterone imbalance — estrogen dominance — is the most common hormonal driver of heavy periods in women without significant structural pathology. And it is deeply influenced by factors within your control: gut health, liver function, stress load, nutritional status, and environmental estrogen exposure.

Root Causes

Poor estrogen clearance through the liver

The liver is responsible for processing and conjugating estrogen into water-soluble metabolites that can be excreted through bile and eventually through the bowel. This is a two-phase process: Phase I converts estrogen into intermediate metabolites (some of which are more potent than estradiol itself), and Phase II conjugates them for excretion. When Phase I is overactive or Phase II is insufficient — due to nutrient deficiencies, alcohol consumption, high toxic burden, or poor diet — more aggressive estrogen metabolites accumulate and recirculate.

Cruciferous vegetables are particularly powerful liver supports for estrogen metabolism. Their active compounds (indole-3-carbinol and DIM) specifically promote the less estrogenic metabolic pathways in Phase I, and DIM supplementation is one of the most well-supported nutritional interventions for estrogen dominance.

Gut dysbiosis and the estrobolome

Once estrogen metabolites reach the gut in their conjugated (deactivated) form, they should be excreted in the stool. But specific gut bacteria — collectively called the estrobolome — produce an enzyme called beta-glucuronidase that cleaves the conjugate, reactivating the estrogen and allowing it to be reabsorbed through the gut wall and re-enter circulation. When the gut microbiome is disrupted — by antibiotic use, high-sugar diets, chronic stress, or insufficient dietary fibre — beta-glucuronidase activity rises, estrogen recirculates, and systemic estrogen load increases.

Constipation makes this worse: the longer stool (and the estrogen in it) remains in the colon, the more opportunity there is for reabsorption. Regular bowel movements — at least once daily — are a genuine clinical target for estrogen dominance and heavy periods.

Environmental estrogen exposure

Xenoestrogens — synthetic or naturally occurring compounds that mimic estrogen — add to the body's overall estrogenic load and compete for estrogen receptors. Common sources include BPA and other plasticisers in plastic food containers, water bottles, and food packaging; phthalates in personal care products and fragrances; pesticide residues on conventionally grown produce; and synthetic hormones in the food supply. While each individual exposure may seem small, cumulative daily exposure across multiple sources contributes meaningfully to estrogen dominance over time.

Practical reductions: switch to glass, stainless steel, or ceramic food and drink containers; avoid heating food in plastic; choose fragrance-free personal care products; eat organic produce where possible (particularly the "dirty dozen" highest-pesticide foods); and filter your drinking water.

Chronic stress and its downstream effects

Chronic stress drives cortisol production, which competes with progesterone for the same biosynthetic precursor (pregnenolone). This reduces luteal phase progesterone, deepens the relative estrogen dominance, and — over time — can impair ovulation entirely, removing the primary source of progesterone. Stress also increases gut permeability and disrupts the microbiome, worsening the estrobolome dysregulation that contributes to estrogen recirculation.

Iron deficiency as a consequence and contributor

Iron deficiency is one of the most serious downstream consequences of heavy periods — and one that is frequently untreated or undertreated. Blood loss depletes iron stores over time; without adequate replacement through diet or supplementation, ferritin (the body's iron storage protein) falls, and eventually haemoglobin follows, resulting in iron deficiency anaemia. Symptoms include profound fatigue, shortness of breath on exertion, heart palpitations, difficulty concentrating, cold intolerance, hair loss, brittle nails, and an increased susceptibility to infections.

What is less well known is that iron deficiency can also worsen menstrual bleeding itself — iron is involved in the synthesis of enzymes that support platelet function and clotting. This creates a self-perpetuating cycle: heavy bleeding depletes iron, which impairs clotting, which worsens bleeding.

What to Do

Address estrogen dominance through the liver and gut

This is the foundation of the nutritional approach to heavy periods driven by hormonal imbalance:

• •Eat cruciferous vegetables daily — broccoli, cauliflower, Brussels sprouts, kale, cabbage, and rocket. At least one to two cups daily. Their DIM content supports healthy estrogen metabolism through the liver.
• •Increase dietary fibre significantly — targeting 30–35 g per day from vegetables, legumes, whole grains, seeds, and fruit. Fibre binds estrogen in the gut and ensures it is excreted rather than reabsorbed. Flaxseeds are particularly useful: they contain lignans that modulate estrogen receptor activity.
• •Reduce or eliminate alcohol — alcohol impairs hepatic estrogen metabolism and significantly raises circulating estrogen levels. Even moderate consumption has a meaningful effect on the estrogen load.
• •Support gut health — include fermented foods (kefir, sauerkraut, kimchi, natural yoghurt), a diverse range of plant foods to support microbiome diversity, and address any digestive symptoms that suggest gut dysbiosis or poor motility.
• •Reduce exposure to xenoestrogens — switch to glass and stainless steel containers, choose fragrance-free personal care products, and prioritise organic produce for the highest-pesticide foods.

Replenish iron urgently

If you have heavy periods and haven't had your ferritin tested recently, this should be a priority. Iron repletion typically requires supplementation — food sources alone are rarely sufficient to replenish significantly depleted stores. Iron bisglycinate is the best-tolerated and most well-absorbed oral iron form; it causes significantly less gastrointestinal upset than ferrous sulphate. Vitamin C taken alongside iron dramatically improves absorption. Avoid coffee, tea, and calcium-rich foods within an hour of taking iron, as they inhibit absorption.

Include iron-rich foods daily as part of your broader nutritional strategy: red meat and organ meats (particularly liver — the richest dietary source of bioavailable haem iron), dark poultry meat, sardines, and — for non-haem iron — legumes, dark leafy greens, pumpkin seeds, and fortified foods, always eaten with a vitamin C source.

Key supplements for heavy periods

• •DIM (diindylmethane, 100–200 mg daily) — concentrated cruciferous extract that supports healthy estrogen metabolism. Promotes the production of less estrogenic, more protective estrogen metabolites through Phase I liver metabolism.
• •Calcium d-glucarate (300–500 mg daily) — supports Phase II liver detoxification by inhibiting beta-glucuronidase activity in the gut, preventing the reactivation and reabsorption of estrogen metabolites. Particularly useful alongside DIM.
• •Magnesium glycinate (300–400 mg daily) — reduces prostaglandin production, supports liver estrogen metabolism, and helps with the cramping that often accompanies heavy bleeding. Depleted by stress, alcohol, and poor diet.
• •Vitamin A (from food or supplement) — essential for healthy uterine lining integrity and normal endometrial development. Severe vitamin A deficiency has been associated with heavy periods. Food sources include liver, egg yolks, and full-fat dairy. Consult a practitioner before supplementing with retinol, particularly if there is any possibility of pregnancy.
• •Iron bisglycinate (dosed per ferritin result) — essential if ferritin is low. Work with a practitioner to dose appropriately for your levels and retest every 3–4 months to track repletion.

Medical options worth knowing about

I always recommend working to address root causes — but it's also useful to know what evidence-based medical options exist for managing heavy bleeding, particularly while you're working on the underlying drivers:

• •Tranexamic acid — a non-hormonal medication taken during the period that reduces bleeding by inhibiting clot breakdown. It does not address the underlying cause but can significantly reduce blood loss on heavy days. It is prescription-only and taken only during menstruation, not throughout the cycle.
• •NSAIDs (ibuprofen, naproxen) — taken regularly from the start of menstruation, NSAIDs reduce prostaglandin production and can reduce blood loss by up to 30–40% alongside their pain-relieving effect.
• •Mirena IUD — the levonorgestrel-releasing IUD can dramatically reduce menstrual blood loss in women with heavy periods and is sometimes used as a management option for fibroids and adenomyosis. It contains a synthetic progestin rather than bioidentical progesterone, and its effects and trade-offs should be discussed in detail with a healthcare provider.
• •Surgical options — for significant structural causes (large fibroids, polyps, adenomyosis), surgical intervention (myomectomy, polypectomy, endometrial ablation, or in severe cases hysterectomy) may be the most effective management. These should be discussed thoroughly with a specialist gynaecologist.

Getting the Right Support

Heavy periods warrant a proper medical investigation — not just reassurance that "some women bleed more." The key investigations are:

• •Pelvic ultrasound — to assess for fibroids, polyps, adenomyosis, and endometrial thickness
• •Full blood count and ferritin — to assess for anaemia and iron deficiency
• •Thyroid panel — TSH, Free T3, Free T4, and thyroid antibodies
• •Hormone panel — including mid-luteal progesterone, estradiol, LH, FSH, and androgens
• •Clotting screen — if there is a personal or family history of easy bruising, nosebleeds, or bleeding disorders, including von Willebrand factor assay

From a nutritional and lifestyle perspective, meaningful improvements in heavy bleeding typically require 3–6 months of consistent effort. Estrogen clearance pathways take time to improve; the gut microbiome responds over weeks to months; structural issues like fibroids are influenced by the hormonal environment over a longer timeframe. Iron deficiency should be addressed urgently and confirmed replete through retesting.

I've worked with many women who had been bleeding heavily for years — some of whom had been told surgery was their only option — who significantly reduced their flow through targeted hormonal and nutritional support. The body has a genuine capacity to rebalance when given the right conditions. Understanding what's driving your heavy periods is the first, most important step toward changing it.