The Functional Medicine Guide to Heavy Periods: Why They Happen and How to Heal Naturally

By Samantha Mihaka, Clinical Nutritionist & Functional Medicine Practitioner
InHer Health Clinic

Understanding Heavy Menstrual Bleeding

If your period is so heavy that you need to double up on protection, set alarms through the night, or you’re constantly worried about leaking - you’re not alone. Heavy menstrual bleeding (HMB), medically called menorrhagia, affects around one in four women at some stage in their lives.

It’s more than just an inconvenience. It can lead to fatigue, iron deficiency, hormonal chaos, and over time, real burnout of the body and mind.

Clinically, heavy menstrual bleeding is defined as blood loss exceeding 80 mL per cycle - but most of us don’t measure that. Instead, we look at functional signs:

• Periods lasting longer than seven days

• Passing clots larger than a 10 cent coin

• Soaking through pads, tampons, or cups every hour

• Feeling dizzy or drained after your bleed

If that’s you, it’s time to dig deeper - not just medicate the symptom.

Why Heavy Periods Are So Common

Periods are a mirror of your internal environment. They reflect the balance (or imbalance) between hormones, inflammation, and nutrient status. Heavy bleeding is rarely random. It’s usually the body’s way of saying, “Something in this system needs attention.”

Here are the most common underlying factors I see in clinic:

1. Low progesterone or unopposed estrogen dominance

2. Iron dysregulation (either deficiency or overload)

3. Mast cell activation and histamine excess

4. Thyroid dysfunction

5. Uterine conditions like fibroids, polyps, or adenomyosis

6. Insulin resistance and metabolic imbalance

7. Perimenopause hormonal changes

Each of these factors influences the uterine lining, blood vessel tone, and how easily (or not) the body can contract to stop bleeding once menstruation starts.

The Hormonal Connection: Estrogen and Progesterone

The menstrual lining grows under the influence of estrogen - a growth-stimulating hormone that thickens the endometrium each cycle. When progesterone is released after ovulation, it helps mature and stabilise that lining.

If ovulation doesn’t occur (a “anovulatory cycle”), progesterone remains low. That leaves estrogen “unchecked,” and the uterine lining continues to build without regulation - leading to heavier, longer, more clotty bleeding.

This is one reason why:

• Teenagers (whose ovulation is often inconsistent) and

• Women in their 40s (whose ovulation starts to decline)

…tend to experience the heaviest bleeds.

What low progesterone looks like

You may have:

• Short luteal phases (<10 days after ovulation)

• PMS, mood swings, or anxiety pre-period

• Spotting before your period

• Sleep troubles or night sweats

• Difficulty maintaining pregnancy

Clinically, I see progesterone as a calming hormone - for both the uterus and the mind. When it’s low, everything feels more intense.

The Immune & Inflammatory Layer: Mast Cells and Histamine

One of the lesser-known causes of heavy bleeding is mast cell activation - an immune response that also shows up in allergies, hives, asthma, and food sensitivities.

Mast cells live in the uterine lining and release histamine and heparin. Histamine increases blood flow and inflammation, while heparin is a natural blood thinner. When overactive, this duo can make bleeding much heavier.

Interestingly, estrogen can activate mast cells, while progesterone helps to stabilise them. That’s another reason why hormonal balance is so closely tied to inflammation, period pain, and flow volume.

The Role of Diet and Food Sensitivities

A1 (cows) Dairy and BCM7

Modern cow’s milk (A1 beta-casein) breaks down into a peptide called beta-casomorphin-7 (BCM7), which can activate immune pathways and mast cells in sensitive individuals.

Many women find that reducing or eliminating A1 (a.k.a. cows) dairy for three cycles can dramatically change their bleeding pattern, especially when heavy bleeding is accompanied by sinus issues, acne, or gut discomfort.

Instead, try:

• A2 dairy (from A2 or Jersey cows)

• Goat or sheep’s milk products

• Butter (low in casein)

• Plant milks like almond or oat

Histamine-Rich Foods

Fermented, aged, and processed foods - like wine, cheese, vinegar, smoked meats, and kombucha - can worsen mast cell activity. Reducing these during your luteal phase (the two weeks before your period) can ease flow and PMS symptoms.

The Iron Connection: Cause and Effect

Heavy bleeding and low iron go hand-in-hand - but it’s a chicken-and-egg scenario.

• Heavy periods deplete iron stores, leading to fatigue, shortness of breath, and brain fog.

• But low iron itself can also increase bleeding because it affects clotting and uterine muscle tone.

A full iron studies panel (including ferritin, serum iron, TIBC, and transferrin saturation) gives the clearest picture.

Optimal ferritin for women is often between 50–100 µg/L. If yours is lower than that, it may worsen menstrual flow and energy levels.

I usually recommend gentle, chelated iron forms (like iron bisglycinate) alongside vitamin C and a protein-rich meal to support absorption - without the constipation that often accompanies cheap iron tablets.

The Role of Prostaglandins, NSAIDs, and Zinc

During menstruation, the uterus releases compounds called prostaglandins. They help the uterus contract - but too many cause cramps, inflammation, and increased bleeding.

NSAIDs (nonsteroidal anti-inflammatory drugs like ibuprofen) reduce prostaglandin levels and can lower menstrual blood loss by 30–50%. For those who tolerate them, they’re an effective short-term strategy for very heavy days.

However, there are natural prostaglandin modulators too - one of the best is zinc.

Zinc supports progesterone production, calms mast cells, and reduces inflammation. I often prescribe 30 mg elemental zinc daily with food during the luteal phase and menstruation. It can also improve acne and immune resilience.

Insulin Resistance and the Metabolic Link

Another overlooked driver of heavy bleeding is insulin resistance.

High insulin increases aromatase activity, which converts more androgens into estrogen - feeding into estrogen dominance. It also thickens the uterine lining and suppresses ovulation, lowering progesterone further.

If you have PCOS symptoms, sugar cravings, or difficulty losing weight around the midsection, addressing blood sugar balance is essential.

Functional testing (like a fasting insulin test, not just glucose) can reveal early insulin issues long before they show up on standard lab ranges.

The Thyroid and Heavy Periods

Thyroid hormones regulate metabolism - and that includes uterine and ovarian function.

Low thyroid function (hypothyroidism) can reduce progesterone and slow clotting, leading to heavy or prolonged bleeding.

Common signs include:

• Cold hands and feet

• Fatigue and brain fog

• Weight gain despite normal eating

• Dry skin, hair loss, or constipation

For anyone with ongoing heavy bleeding and low energy, I recommend a full thyroid panel (TSH, Free T4, Free T3, and thyroid antibodies). Optimising thyroid function often dramatically improves period regularity.

Perimenopause: Flooding Periods and Hormone Chaos

Women in their late 30s and 40s may experience “flooding” periods - where bleeding suddenly becomes excessive and unpredictable.

This stage, known as perimenopause, is marked by fluctuating estrogen and declining progesterone. Ovulation may occur sporadically, if at all.

During this time, the uterine lining can become very thick, making bleeds heavier and longer.

Beyond diet and supplements, this is often where bioidentical progesterone therapy can be life-changing.

Bioidentical Progesterone: Nature’s Balancer

“Real” or micronised progesterone (Prometrium, Utrogestan) is chemically identical to the hormone your body naturally produces.

Unlike synthetic progestins (found in the pill or hormonal IUDs), micronised progesterone:

• Lightens bleeding by thinning the uterine lining

• Improves mood, sleep, and anxiety

• Supports bone and breast health

• Stabilises mast cells and histamine

For many women, 100–300 mg orally at night for the luteal phase (or as prescribed by your practitioner) can regulate cycles and dramatically reduce flow. Please note, this is not something I prescribe and is out of my scope - but can support you as you venture into this space (as needed).

Reference: Prior, J.C. (2017). Managing Menorrhagia Without Surgery. Centre for Menstrual Cycle and Ovulation Research (CeMCOR), University of British Columbia.

Natural Therapeutic Nutrients and Botanicals

1. Quercetin

A potent bioflavonoid that calms mast cells, reduces histamine, and supports anti-inflammatory pathways. Found naturally in apples, onions, and capers — or in supplement form at 250–500 mg daily.

2. Turmeric (Curcumin)

Anti-inflammatory and mast-cell stabilising; supports detoxification and liver clearance of estrogen. Works synergistically with quercetin.

3. Calcium D-Glucarate

Aids phase II liver detoxification and estrogen metabolism. Excellent for those with estrogen dominance or sluggish bowel clearance.

4. Magnesium

Relaxes the uterus, reduces cramping, supports progesterone synthesis, and calms the nervous system. Many women benefit from 300–400 mg daily, ideally as magnesium glycinate or citrate.

5. Iodine

Regulates both thyroid and estrogen metabolism. It can reduce cyclic breast tenderness and normalize estrogen-driven bleeding when used appropriately under supervision.

Step-by-Step Healing Framework

• Assess the Root Cause

   Full bloods (iron, thyroid, insulin, progesterone, estrogen, FSH/LH)

  Ultrasound if fibroids, polyps, or adenomyosis are suspected

• Stabilise the Foundation

  Balance blood sugar (protein at each meal, lower refined carbs)

  Increase cruciferous vegetables for liver clearance

  Optimise sleep and stress management (these directly affect progesterone)

• Reduce Inflammation

  Eliminate A1 (cows) dairy for at least 3 cycles

  Reduce alcohol and histamine-rich foods

  Add turmeric, quercetin, and omega-3s

• Nourish the Uterus and Rebuild Nutrients

  Check ferritin and supplement iron if low

  Add zinc, magnesium, and B6

  Support gut health with probiotics and fibre

• Balance Hormones

  Address ovulatory issues with nutrition and lifestyle

  Discuss bioidentical progesterone if clinically indicated

  Reassess every 3 months for cycle and symptom changes

When to Seek Further Investigation

If your bleeding is:

• Soaking through pads or tampons every hour for several hours

• Accompanied by severe pain or clotting

• Causing anemia or fatigue despite intervention

… then further workup is warranted. This may include:

• Pelvic ultrasound

• Endometrial biopsy (for women over 40 or with risk factors)

• Hysteroscopy (to check for fibroids or polyps)

Functional practitioners like myself can work collaboratively with your GP or gynaecologist to ensure you receive both investigative care and natural management.

The Functional Medicine Perspective

From a root-cause viewpoint, heavy bleeding is not just a “uterine issue.” It’s a signal of systemic imbalance - metabolic, hormonal, and inflammatory.

By identifying patterns - whether it’s poor detoxification, blood sugar dysregulation, histamine excess, or thyroid sluggishness - we can bring the body back into rhythm.

Your menstrual cycle is not a monthly punishment. It’s an incredible barometer of your health. When we restore harmony between your hormones, immune system, and nutrient status, your flow naturally finds balance.

Final Thoughts

You don’t have to live at the mercy of heavy, exhausting periods.
There is always a reason - and with the right testing, nourishment, and tailored treatment, there is always a way forward.

If you’re experiencing ongoing heavy bleeding, fatigue, or hormonal chaos, it may be time to take a functional, whole-body look at your cycle.

At InHer Health Clinic, we specialise in translating complex hormone science into real, sustainable healing strategies - blending functional testing, nutrition, and lifestyle medicine to restore balance from the inside out. Check out HORMONE REHAB PROGRAMME

References

• Briden, L. (2020). Period Repair Manual. Pan Macmillan.

• Prior, J.C. (2017). Managing Menorrhagia Without Surgery. Centre for Menstrual Cycle and Ovulation Research (CeMCOR).

• Warner, P. et al. (2004). “Menorrhagia I: measured blood loss, clinical features, and outcome in women with heavy periods.” BJOG 111(10): 997–1002.

• Munro, M.G. et al. (2011). “FIGO classification system (PALM–COEIN) for causes of abnormal uterine bleeding.” Int J Gynaecol Obstet, 113(1): 3–13.

• Aghajanova, L., & Giudice, L.C. (2011). “Molecular evidence for differences in endometrial receptivity.” Reproductive Sciences, 18(4): 476–482.