If there is one mineral I find myself talking about more than any other, it is magnesium. It is involved in over three hundred processes in the body, it is one of the minerals most of us are quietly short on, and it sits underneath so many of the symptoms women come to me about: the cramping, the poor sleep, the wired-and-tired feeling, the low mood in the week before a period.

It is not a magic fix, and I will always be honest about that. But magnesium is genuinely one of the most useful and underrated places to start.

What magnesium actually does

Magnesium is a cofactor, which means it is the thing that allows other reactions to happen. Without enough of it, hundreds of processes run less efficiently. For hormonal health specifically, a few of its roles matter most.

It is a natural muscle relaxant, which is why it comes up so often for period cramps. Your uterus is a muscle, and when it contracts hard during your period, magnesium helps it release rather than spasm.

It regulates your stress response. Magnesium helps calm the HPA axis, the system that governs cortisol. And because chronically high cortisol disrupts ovulation, sleep and blood sugar, supporting that system is genuinely hormonal work rather than just stress management.

It supports blood sugar regulation, helping insulin do its job properly. Since blood sugar swings drive cravings, mood dips and the androgen problems central to PCOS, this connection matters more than it first appears.

And it supports sleep, partly through that same calming effect on the nervous system, and partly through its role in producing melatonin. Magnesium also helps regulate GABA, the neurotransmitter responsible for quietening mental activity, which is why low magnesium so often shows up as a mind that will not switch off at bedtime despite genuine exhaustion.

There is a hormone production angle too, which is less widely discussed. Magnesium is involved in the enzymatic processes that produce steroid hormones, including oestrogen and progesterone, and it supports the liver enzymes that break those hormones down once they have done their job. So it sits on both sides of the equation: helping make the hormones, and helping clear them afterwards. When magnesium is short, both processes run less efficiently.

It also plays a role in thyroid function, supporting the conversion of T4, the storage form of thyroid hormone, into T3, the active form your cells actually use. Since thyroid hormones govern the rate at which everything in your body runs, including your menstrual cycle, this is a quiet but genuinely important connection.

Here is the frustrating part: stress itself depletes magnesium. So the more stressed you are, the more you burn through, and the lower your levels drop, which makes you less able to handle stress. It is a genuine loop, and one worth interrupting.

Why so many women are short on it

Magnesium levels in food have fallen over recent decades as soil quality has declined, so even a good diet delivers less than it once did. Refined foods lose most of their magnesium in processing. Stress depletes it, as does high alcohol intake, and certain medications interfere with absorption.

Blood tests are also unhelpful here, because only about one per cent of your body’s magnesium is in your blood, the rest is in bone and tissue. Your body works hard to keep blood levels stable, drawing from your bones if it needs to, so a normal blood result does not necessarily mean your stores are good. This is part of why suboptimal magnesium so often goes unnoticed for years.

Signs worth paying attention to. Because there is no reliable routine test, most practitioners work from symptoms. Muscle cramps and twitches, particularly in the calves or eyelids, are classic. So are restless legs at night, difficulty falling asleep despite tiredness, headaches or migraines, constipation, heart palpitations, anxiety or feeling constantly on edge, sugar cravings especially for chocolate, and PMS that feels disproportionate. None of these prove low magnesium on their own, and each has other possible causes worth ruling out with your GP. But if several cluster together, particularly around your luteal phase, magnesium is a genuinely sensible place to start.

Who is most likely to be short. Anyone under sustained stress, since cortisol production burns through magnesium. Anyone eating largely processed or refined food, since processing strips it. Those drinking alcohol regularly, as it increases urinary excretion. People on certain medications, particularly proton pump inhibitors for reflux and some diuretics, which interfere with absorption. Those with digestive conditions affecting absorption, such as coeliac disease or inflammatory bowel disease. And anyone exercising very intensely, since magnesium is lost through sweat.

Magnesium across your cycle

The luteal phase, the stretch between ovulation and your period, is when magnesium matters most. Research suggests magnesium levels may dip in this phase for some women, right when the symptoms it helps with, cramping, irritability, poor sleep, sugar cravings, are at their peak.

This is why so many women crave chocolate premenstrually. Dark chocolate is genuinely one of the richest food sources of magnesium, and there is a reasonable argument that the craving is your body asking for something specific rather than simply a lack of willpower.

Practically, this means leaning into magnesium-rich foods more deliberately in the second half of your cycle, and being especially consistent with them in the week before your period.

There is a compounding effect worth understanding here too. In the luteal phase, insulin sensitivity naturally decreases under the influence of progesterone, meaning blood sugar swings more easily. Those swings drive cortisol, cortisol depletes magnesium, and low magnesium worsens both the mood symptoms and the cravings that started the cycle. Supporting magnesium in this phase interrupts that loop at a genuinely useful point.

This is also why magnesium and blood sugar strategies work so much better together than either alone. A magnesium-rich snack that also contains protein and fat, rather than magnesium-rich chocolate on its own, addresses both sides at once.

Where to find it in food

Food first, always. These are the richest sources worth building into your week:

• Pumpkin seeds, one of the very best sources, and easy to scatter over almost anything.
• Dark leafy greens, particularly spinach, chard and kale.
• Dark chocolate, ideally seventy per cent or above.
• Almonds and cashews, a small handful goes a long way.
• Black beans, chickpeas and lentils, which bring fibre and protein alongside.
• Avocado, which also brings healthy fats.
• Wholegrains like brown rice, quinoa and oats.
• Oily fish such as mackerel and salmon.

To give you a sense of scale, adult women in the UK are advised to get around 270mg of magnesium daily. A 30g handful of pumpkin seeds delivers roughly 150mg, which is a substantial portion of the day in one small handful. A cup of cooked spinach gives around 155mg. A 30g serving of dark chocolate at seventy per cent or above gives around 65mg. An avocado gives roughly 58mg. So it is genuinely achievable through food, but only if you eat these things deliberately rather than occasionally.

A genuinely lovely combination for the luteal phase: full-fat yoghurt topped with pumpkin seeds, a square of grated dark chocolate and a drizzle of almond butter. Magnesium from three sources, plus protein and fat to steady blood sugar, which compounds the benefit.

A note on absorption. Magnesium from food is generally well absorbed, but a few things interfere. Very high calcium intake at the same meal competes for absorption, so if you take a calcium supplement, space it apart from magnesium-rich meals. Phytates in unsoaked grains and legumes bind minerals and reduce uptake, which is one practical argument for soaking beans and grains where you can. And low stomach acid, common as we age or with long-term reflux medication, reduces absorption of most minerals including this one.

Magnesium and specific hormonal conditions

PMS and PMDD. This is where magnesium has the most direct evidence. Several studies have looked at magnesium for premenstrual symptoms, with reasonable results for mood symptoms, fluid retention and breast tenderness, particularly when combined with vitamin B6. B6 appears to improve magnesium uptake into cells, which is why the two are so often paired in supplements aimed at PMS. Food sources of B6 include bananas, chickpeas, salmon, potatoes and sunflower seeds, so pairing those with magnesium-rich foods is a sensible everyday approach.

Period pain. Magnesium’s muscle-relaxant effect applies directly to the uterine muscle, and there is research suggesting supplementation can reduce period pain intensity. It appears to work partly by reducing prostaglandins, the inflammatory compounds that drive uterine cramping in the first place. Starting a few days before your period is due, rather than once cramping has begun, tends to be the more effective approach.

PCOS. Women with PCOS are more likely to have lower magnesium levels, and given magnesium’s role in insulin sensitivity, this matters. Insulin resistance drives androgen production in PCOS, so anything supporting insulin function supports the whole picture. Magnesium is not a treatment for PCOS, but it is a reasonable part of the nutritional foundation alongside the blood sugar strategies that do the heavy lifting.

Perimenopause. As oestrogen declines, sleep disruption, anxiety and heart palpitations become common, all areas where magnesium plays a role. It also becomes more important for bone health at this stage, since magnesium is required for calcium to be properly incorporated into bone. Roughly sixty per cent of your body’s magnesium is stored in bone, which tells you something about how central it is there.

Thyroid conditions. Given magnesium’s role in T4 to T3 conversion, it is worth being mindful of if you have a thyroid condition. It does not replace thyroid medication, and it should not be taken at the same time as levothyroxine, since minerals interfere with its absorption. Leave at least four hours between them.

If you are considering a supplement

Food should come first, but supplements have their place, particularly in the luteal phase or through stressful stretches. The form genuinely matters here, because they are absorbed very differently.

• Magnesium glycinate is the one I most often see recommended for sleep, stress and PMS. It is well absorbed and gentle on the stomach.
• Magnesium citrate is well absorbed too, but has a laxative effect, which is useful if constipation is part of your picture and unhelpful if it is not.
• Magnesium oxide is cheap and very common in supermarket supplements, but poorly absorbed. Worth avoiding if you can.
• Magnesium malate is often suggested for fatigue and muscle pain.
• Magnesium taurate is sometimes suggested where heart palpitations or blood pressure are part of the picture.
• Magnesium L-threonate is the form most studied for crossing into the brain, so it appears in products aimed at cognition and mood, though it is considerably more expensive.

On dosing and timing. Supplemental doses commonly sit somewhere between 200mg and 400mg of elemental magnesium daily, though this varies by individual and by form, so it is worth checking labels carefully. The number on the front of the bottle often refers to the compound rather than the elemental magnesium it actually delivers, which can be a considerably smaller figure. Taking it in the evening suits most people, given the sleep and relaxation benefits, and splitting a larger dose across the day improves absorption compared with taking it all at once.

The main sign of taking too much is loose stools, which is your body’s way of telling you it cannot absorb any more. If that happens, reduce the dose or switch to a gentler form like glycinate.

Topical magnesium, sprays and flakes in the bath, is popular and pleasant, though the evidence for absorption through skin is genuinely weaker than for oral forms. A magnesium bath before bed may help you relax, but treat it as a lovely ritual rather than your main source.

Please do check with your GP or pharmacist before starting a supplement if you are pregnant, breastfeeding, on medication, or have any kidney condition, as magnesium is cleared by the kidneys.

Realistic expectations

Magnesium is not going to transform your hormones overnight. What it can genuinely do, over a few cycles of consistent intake, is take the edge off cramping, help you sleep more soundly, steady your stress response and soften the sharper edges of PMS.

That is a meaningful set of improvements, but it works best as part of a bigger picture rather than in isolation. Steady blood sugar, decent sleep, gentle movement and managing stress all matter alongside it, and they all support each other.

Start with food. Build the magnesium-rich options into your normal week rather than treating them as a chore. Lean into them harder in your luteal phase. And if you want to try a supplement, choose the form thoughtfully and give it two or three cycles before you judge it.

Magnesium works best alongside the basics: blood sugar balance, good gut health so you actually absorb it, and understanding your cycle so you know when you need it most. Coming off the pill is worth reading if you are re-establishing a natural cycle. If you would like help putting it together, do get in touch, or read more about working together one-to-one.

Written by

Brydee Thomas

Holistic health coach and founder of Radiant Bloom, supporting women through trying to conceive, pregnancy and the postpartum months. Evidence-based guidance, no programmes and no generic plans.