The menstrual cycle is a complex weave of cyclical changes that occur throughout the month, as well as throughout the year and our whole life span. Hormone fluctuations are part of the fabric of female health, which are affected by overall health and vice versa. Working with these fluctuations can allow us to be more connected to our body’s own rhythm but when they are out of sync there can be significant symptoms and may give a window into other underlying dysfunctions.

Premenstrual syndrome (PMS) is a combination of physical, emotional, and behavioural of symptoms which can occur with two weeks of menstruating, but not during the rest of the cycle, and can affect individuals differently. A worldwide survey found that around 90% of women experience at least one premenstrual symptom and half said having a period negatively impacts their life (wellbeingofwomen.org.uk). In this blog we look at the physiology of the menstrual cycle, how we can work with hormone fluctuations and provide interventions to balance hormones.

Hormones and the menstrual cycle

The menstrual cycle is a highly tuned interplay between the brain and the ovaries involving 4 key hormones: follicle stimulating hormone (FSH), luteinising hormone (LH), oestrogen and progestogen. The balance of oestrogen and progesterone are particularly influential when looking at symptoms and drivers of PMS.

Oestrogen is a growth promoting, stimulatory hormone which is essential for the development of the endometrial lining. It has multiple other functions, including promoting the production of serotonin and dopamine, neurotransmitters associated with contentedness and ​motivation. (Bendis, 2024​) Higher oestrogen during the luteal phase contributes to bloating, breast tenderness, mood swings, anxiety and heavy or painful periods.

Progesterone prepares the body for pregnancy by maintaining and thickening the uterus lining. A metabolite of progestogen, allopregnanolone, stimulates GABA our inhibitory neurotransmitter signalling and is therefore associated with feelings of calm and relaxation ​(Paul, 2020)​.

PMS is often experienced when these hormones are out of balance.

Firstly, it is important to understand natural hormones fluctuations across the menstrual cycle:

1. Follicular Phase (typically lasts 14 – 21 days)

This phase starts on day 1 of the period (first day of bleeding) and lasts until ovulation, this can be divided into 2 parts. The first part of the follicular phase is the menstrual phase. It is when reproductive hormones are at their lowest and can experience low energy, mood swings, cramping, bloating and brain fog.

Best time for: Comforting, nourishing and warming foods which replace lost nutrients including iron. Exercise should be gentle (Pelz, 2022).

The second part of the follicular phase (after menstruation finishes) hormones are rising. During this phase brain releases FSH, which stimulates the ovaries to grow several follicles which produce oestrogen. Oestrogen levels then rise, boosting energy, motivation and cognitive sharpness.

Best time for: Boosting metabolism with protein rich foods and strength training, can include fasting at this time as are more resilient (Pelz, 2022).

2. Ovulation (lasts 1-3 days – usually 15-17)

At the end of the follicular phase, the brain releases LH, triggering ovulation, the release of the egg from the follicle. Oestrogen and testosterone peak, giving revitalised energy, strength and peak fertility. After the egg is released, it travels down the fallopian tube where it waits to be fertilised. This is the point of the cycle when conception is possible.

Best time for: Light fresh summer meals, salads, can include fast paced exercise such as running, cycling or HIIT (Pelz, 2022).

3. Luteal Phase (lasts 14 days)

After ovulation, the now empty follicle that released the egg rapidly restructures itself to form a corpus luteum, a unique and vascularised structure that secretes progesterone. Progesterone stabilises mood, supports sleep, increases body temperature and prepares the uterus for pregnancy.

This is where energy is falling and we enter a calmer more restful phase, oestrogen falls and progesterone becomes more dominant, but symptoms of PMS are experienced. This may be exacerbated by a disconnect with the flow state. If we can appreciate the luteal phase is a time for rest and reflection, then often the experience can be much less turbulent. From an evolutionary point of view this is the phase where we may be expecting a pregnancy and therefore makes sense that energy is lower and we become more restful.

Best time for: Nourishing fibre containing and magnesium rich foods e.g. leafy greens, dark chocolate to support cramps and mood. Light and very gentle exercise such as walking or gentle yoga (Pelz, 2022).

Oestrogen dominance

Oestrogen dominance is a situation where oestrogen levels are high relative to progesterone, either because oestrogen is too high, progesterone is too low (or a combination of both). This imbalance, particularly during the luteal phase (the two weeks before a period), is a primary driver of PMS and may also be associated with other conditions including endometriosis, fibroids and an increased risk of breast cancer.

There are a few reasons why oestrogen levels may be higher:

1. The body is producing too much oestrogen or not enough progesterone.

All steroid hormones are manufactured from the master steroid hormone, pregnenolone. Genetics, nutrition and lifestyle can influence pathways which convert pregnenolone into other hormones, including progesterone and oestrogen. For example, alcohol and stress can upregulate pathways which produce oestrogen as well as cortisol which in turn down regulates the production of progesterone ​(Kolatorova, 2022).​ Therefore, stress exacerbates oestrogen dominance and further increases anxiety by reducing the production of progesterone metabolites which are agonists of GABA receptors responsible for promoting calm relaxation. ​(Bland, 2008)​.

Testosterone is converted to oestrogen via aromatisation. This occurs in the adrenal glands but also in adipose tissue. A higher level of body fat can increase the production of aromatisation enzymes, hence increasing the conversion of testosterone to oestrogen which contributes to oestrogen dominance ​(Kuryłowicz, 2023)​. Reducing body fat in those who have increased adiposity can help to balance hormone levels.

2. Exposure to external oestrogen (or oestrogen agonists)

Exposure to environmental oestrogens, which can bind to oestrogen receptors and upregulate the oestrogenic response, can exacerbate or even cause oestrogen dominance as well as promoting growth and hence cancer risk.

These are known as xenoestrogens and are found in many synthetic products, examples include BPA, parabens, PCBs, phthalates. Exposure can be reduced by avoiding soft plastics, pesticides, toxic cosmetics and cleaning products ​(Paterni, 2017).​

Phytoestrogens are plant compounds which have a similar structure to oestrogen and can bind to oestrogen receptors but, unlike xenoestrogens, they elicit a weaker oestrogenic response. This means that they can block or downregulate excessive or high levels of oestrogen but gently bring up oestrogen levels when they are very low, such as during menopause ​(Domínguez-López, 2020)​. Hence phytoestrogens are described as oestrogen modulators. Examples of phytoestrogens include isoflavones found in soy and red clover, coumestans also in red clover, lignans found in legumes, nuts and seeds, particularly flax seeds and fruits including apricots, peaches and berries.

Isoflavones have been shown to elicit a beneficial effect on the prevention of premenstrual syndrome (Canivenc-Lavier, 2023) and reduce symptoms of PMS, including breast tenderness and headache (Bryant, 2005).

3. The body isn’t detoxifying and excreting oestrogen as it should.

Oestrogen is a fat-soluble hormone. Once it has done its job in the body it is transported to the liver to undergo biotransformation. It must go through phase 1 detoxification, to be made water soluble. Then through phase 2 to be conjugated, or bound, to a carrier molecule so it can be excreted from the body via the bile and the gut (phase 3).

Let’s look at these phases so we can see how and where to provide support.

Phase 1 - Oestrogens are metabolised in the liver firstly by the cytochrome P450 enzyme system, this involves different enzyme pathways such as:

CYP1A1 pathway primarily converts oestrogens to 2-hydroxyoestrogen (2-OH). 2-OH is considered the most beneficial metabolite of oestrogen as it is anti-proliferative and therefore protective particularly against cancer. Phytonutrients Di-indolyl-methane and indole-3-carbinol (produced from glucosinolates) and sulforaphane are found in brassica vegetables such as broccoli (Fahey, 2025) and kale as well as rosemary promote the activity of CYP1A1 enzymes. This enzyme also detoxifies heterocyclic hydrocarbons (found in drugs, dyes and pesticides) therefore high exposure to these may impact oestrogen detoxification. Genetic SNPs may also influence CYP1A1 activity.

CYP1B1 pathway which results in 4-hydroxyoestrogen (4-OH), this form is genotoxic and mutagenic and hence is associated with an increased risk of cancer via DNA damage. This pathway is upregulated by alcohol and stress ​(Castro, 2014).​

CYP2C family and CYP 3A4 resulting in the formation of 16-hydroxyoestrogen (16-OH). 16-OH is highly proliferative but less damaging than 4-OH and therefore is more neutral.

Research suggests that high levels of 4-OH and 16-OH are linked to tumour growth and other oestrogen dominant conditions. Excess 4-OH and 16-OH oestrogen is not necessarily an issue if they are quickly detoxified further via phase 2 ​(Bland J, 2008).

​Phase 2 – this is pathway where oestrogen that has been made water soluble via phase 1 is conjugated to a carrier molecule to be excreted from the body. If phase 2 works adequately the reactive metabolites produced during phase 1 are neutralised. Oestrogen can be conjugated via several pathways which are; (Bland J et al, 2008)

• Methylation – COMT enzymes requiring SAMe (adequate methylation essential – B6, folate, B12), magnesium. Methylation (e.g. MTHFR, MTRR) and COMT SNPs can reduce this pathway.
• Sulphation – supported by sulphur containing nutrients such as cysteine (NAC), methionine and sulphur containing vegetables i.e. onions and garlic and vitamin A.v
• Glucuronidation – addition of glucuronide, requires magnesium and is inhibited by smoking.
• Glutathione conjugation – relies on glutathione including precursors such as NAC, vitamin C, glycine and selenium.

Phase 3 – Excretion/Oestrobolome

Once oestrogen has been conjugated it is removed from the liver and enters the gut via the bile for excretion. The health of the gut and the microbiome play an essential role in the ability for oestrogen to be removed effectively from the body. If the balance of the microbiome is disrupted it can produce beta-glucuronidase. This is an enzyme which deconjugates oestrogen from glucuronide and reabsorption and circulation of waste oestrogen exacerbating oestrogen dominance​(Larnder, 2025).​ It is important to note that constipation will exacerbate oestrogen reabsorption. Calcium d-glucarate has been shown to inhibit beta glucuronidase, which allows oestrogen to be excreted and maintain healthy oestrogen metabolism ​(Hu, 2023).​

Supporting a healthy microbiome with probiotics, prebiotics, polyphenols and fibre is important for helping to regulate oestrogen balance, as reduces the production of beta glucuronidase and the ability for oestrogen to be reabsorbed. A recent placebo-controlled trial study showed that women with endometriosis, taking a probiotic supplement (L. acidophilus/plantarum/fermentum/gasseri) had a significant reduction in menstrual pain and dysmenorrhea compared to the placebo ​(Wu, 2024).​

Is it all about oestrogen though?

PMS can also be associated with psychological symptoms such as mood swings, anxiety and depression which occur within the luteal phase of the menstrual cycle. Interestingly, although PMS symptoms can be attributed to oestrogen dominance, the luteal phase is when oestrogen levels are reducing, and therefore it is curious as to why similar symptoms are not seen in the follicular phase. Although they are influenced by elevated oestrogen levels in relation to progesterone, progesterone signalling may also be altered.

Progesterone metabolite allopregnanolone agonises GABA receptors, having an anxiolytic effect. In women experiencing PMS there is evidence that structural alterations of GABA receptors may change response to allopregnanolone leading to heightened inflammation, disrupted mood and anxiety ​(Hantsoo, 2020)​. This means that some women are more sensitive to changing levels of progesterone and do not adapt to it effectively.

Supporting normal GABA signalling with nutrients that promote GABA including magnesium, B6, l-theanine​(Yoto, 2012)​, l-taurine​ (Schaffer, 2018)​ and lemon balm ​(Mathews, 2024) ​can help to ameliorate PMS symptoms such as anxiety.

To support hormone balance it is useful to:

• Understand that at different times of the month you can feel more or less energised, lean into this, rest when need and take advantage of increased energy and vigour when it is present.
• Consider phytonutrients that support CYP1A1 pathways such as indoles and sulforaphane from broccoli as well as rosemary
• Avoid xenoestrogens in industrial products and increase phytoestrogens in diet and supplementation such as soy or red clover isoflavones
• Manage body weight, stress and alcohol intake.
• Consider cofactors for phase 2 conjugation, methylated B vitamins, magnesium NAC, vitamins A and C and selenium.
• Support GABA with nutrients including magnesium, l-theanine, taurine and lemon balm.
• Other factors such as thyroid dysfunction, inflammation, stress and nutrients deficiencies can also play a role and therefore should be considered.

References

• Bendis, P. C. & Zimmerman, S. (2024). The impact of estradiol on serotonin, glutamate, and dopamine systems. Frontiers in Neuroscience, 18, 1348551.​​
• ​Bland J et al. (2008). Textbook of Functional Medicine.
• Castro, G. D., & Castro, J. A. (2014). Alcohol drinking and mammary cancer: Pathogenesis and potential dietary preventive alternatives. World Journal of Clinical Oncology, 5(4), 713.
• ​Domínguez-López, I & Yago-Aragón, et al. (2020). Effects of Dietary Phytoestrogens on Hormones throughout a Human Lifespan: A Review. Nutrients, 12(8), 2456.
• ​Hantsoo, L. & Epperson, C. N. (2020). Allopregnanolone in premenstrual dysphoric disorder (PMDD): Evidence for dysregulated sensitivity to GABA-A receptor modulating neuroactive steroids across the menstrual cycle. Neurobiology of Stress, 12.
• ​Hu, S. & Ding, Q., et al. (2023). Gut microbial beta-glucuronidase: a vital regulator in female estrogen metabolism. Gut Microbes, 15(1), 2236749.
• Kolatorova, L. & Vitku, J. et al. (2022). Progesterone: A Steroid with Wide Range of Effects in Physiology as Well as Human Medicine. International Journal of Molecular Sciences, 23(14), 7989.
• ​Kuryłowicz, A. (2023). Estrogens in Adipose Tissue Physiology and Obesity-Related Dysfunction. Biomedicines, 11(3), 690.
• Larnder, A. H. & Murphy, R. A et al. (2025). The estrobolome: Estrogen‐metabolizing pathways of the gut microbiome and their relation to breast cancer. International Journal of Cancer, 157(4), 599. 35427
• ​​Mathews, I. M. & Eastwood, J. et al. (2024). Clinical Efficacy and Tolerability of Lemon Balm (Melissa officinalis L.) in Psychological Well-Being: A Review. Nutrients, 16(20), 3545.
• ​Paterni, I. & Granchi, C., et al. (2017). Risks and benefits related to alimentary exposure to xenoestrogens. Critical Reviews in Food Science and Nutrition, 57(16), 3384.
• Paul, S. M. & Pinna, G. et al. (2020). Allopregnanolone: From molecular pathophysiology to therapeutics. A historical perspective. Neurobiology of Stress, 12, 100215.
• Schaffer, S. & Kim, H. W. (2018). Effects and Mechanisms of Taurine as a Therapeutic Agent. Biomolecules & Therapeutics, 26(3), 225–241.
• www.wellbeingofwomen.org.uk/what-we-do/campaigns/just-a-period/just-a-period-survey-results/
• ​Wu, L. Y. & Yang, T. H. et al. (2024). The role of probiotics in women’s health: An update narrative review. Taiwanese Journal of Obstetrics and Gynecology, 63(1), 29–36.
• ​Yoto, A. & Motoki, M. et al. (2012). Effects of L-theanine or caffeine intake on changes in blood pressure under physical and psychological stresses. Journal of Physiological Anthropology, 31(1), 28.

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