You're sleeping seven hours a night. Your diet is reasonably balanced — or so you believe. You don't smoke, you exercise. And yet, for weeks now, the fatigue won't lift. Not the tired-after-a-bad-night kind — the kind that persists even after a full weekend of rest. Your GP ordered blood tests. The result: ferritin at 12 ng/mL. "You have iron deficiency anaemia — you're among the 25% of women of reproductive age in the UK affected." That number surprised you. Not your GP.
This scenario is entirely ordinary. Not because women eat poorly — but because their requirements for certain micronutrients are significantly higher than men's, and these specificities remain poorly understood, even by those affected.
This comprehensive guide covers the ten micronutrients most critical for women's health: iron, calcium, vitamin D, magnesium, folate/B9, omega-3, vitamin B12, iodine — with requirements, best food sources, absorption factors, and when supplementation becomes necessary. Recommendations are aligned with NHS guidelines, the British Nutrition Foundation (BNF), and SACN (Scientific Advisory Committee on Nutrition) guidance.
Iron: why women's needs are twice as high
Women of reproductive age need 14.8 mg of iron per day according to NHS and SACN guidance — almost double the 8.7 mg recommended for men over 18. The reason is straightforward and frequently underestimated: menstruation. An average period results in losses of 15–30 mg of iron per cycle. For women with heavy periods, this can reach 40–50 mg or more.
The result: iron deficiency is the most common nutritional deficiency in the UK. According to NHS data, approximately one in four women of reproductive age in the UK has low iron stores, with rates rising to 40% in pregnant women who are not supplemented. The National Diet and Nutrition Survey (NDNS) consistently shows women's iron intakes falling below recommended levels.
Understanding ferritin: the key marker
Ferritin is the iron storage protein. It's the most relevant marker for detecting early iron deficiency — before haemoglobin drops and clinical anaemia appears. Normal ferritin ranges between 12 and 150 ng/mL in most laboratory references, but many researchers and clinicians now consider that below 30 ng/mL, symptoms of fatigue, difficulty concentrating, and hair loss begin to manifest, even when values fall within the technical "normal range".
This is a recognised blind spot in primary care: a ferritin of 15 ng/mL may be flagged as "normal" but is insufficient to maintain good energy levels and hair quality. If you feel persistently exhausted with ferritin between 10–30, the conversation with your GP is worth having.
Haem vs non-haem iron
- Haem iron (red meat, poultry, fish): absorption rate of 20–25%. Liver is the most concentrated source (around 10 mg/100g), followed by black pudding, beef and lamb (2–4 mg/100g).
- Non-haem iron (pulses, fortified cereals, leafy greens, tofu, seeds): absorption rate of only 5–10%. Cooked lentils (3.3 mg/100g), firm tofu (2.7 mg/100g), cooked spinach (2.7 mg/100g), and pumpkin seeds (8 mg/100g raw) are the strongest plant sources.
Absorption enhancers and blockers
Enhancers:
- Vitamin C: the number one synergist. A glass of orange juice, strawberries, or raw pepper with an iron-rich plant meal can multiply absorption three to fourfold. Practically: lentil soup with lemon juice, spinach salad with cherry tomatoes and red pepper.
- Organic acids (citric, malic) in fresh fruit and vegetables.
- Animal flesh at the same meal also improves non-haem iron absorption.
Blockers:
- Tea and coffee: tannins chelate iron, reducing absorption by up to 60%. Don't drink tea or coffee with or immediately after iron-rich meals. Wait at least an hour.
- Calcium: taken simultaneously, it competes with iron at the intestinal level. Don't take a calcium supplement at the same meal as an iron supplement.
- Phytates: found in wholegrains and pulses. Soaking and cooking reduce them significantly. Sourdough bread is preferable to standard bread in this respect.
- Polyphenols in red wine and dark chocolate.
Diana's advice: Reserve tea and coffee for between meals rather than with them. And routinely add a vitamin C source to plant-based meals. These two habits can meaningfully improve your iron status without any supplementation — and cost nothing beyond a squeeze of lemon or a glass of orange juice.
When to supplement with iron
Iron supplementation is not trivial — excess iron is toxic and promotes oxidative stress. It should only occur on medical advice following biological confirmation (ferritin + haemoglobin). NHS GPs can prescribe ferrous sulphate (the most common UK prescription), but the best-tolerated forms are ferrous bisglycinate and ferrous gluconate. Ferrous sulphate — the oldest and least expensive — frequently causes constipation and nausea.
Warning: Never supplement with iron without prior blood tests. Contrary to popular belief, "taking iron just in case" is not recommended and is potentially harmful. Iron overload is associated with increased oxidative stress and long-term cardiovascular risk. If you're buying over-the-counter iron supplements without a GP recommendation, you may be doing more harm than good.
Calcium: far beyond dairy
Calcium is not merely a bone mineral. It plays roles in muscle contraction, blood clotting, nerve transmission, and blood pressure regulation. But it's its role in skeletal health that makes it particularly critical for women.
Peak bone mass is established by age 25–30. It's then maintained before declining — gradually in adult women, then accelerating at menopause under the effect of falling oestrogen. A woman can lose 1–2% of bone mass per year in the five years following menopause.
Osteoporosis affects one in three women over 50 in the UK according to the Royal Osteoporosis Society. Adequate calcium intake throughout life — not just after 50 — is one of the strongest protective factors.
NHS recommended intakes
- Women aged 19–50: 700 mg/day
- Women over 50: 1,200 mg/day (BNF and ROS recommendation, slightly above NHS baseline)
- Pregnant and breastfeeding women: 1,250 mg/day
Best food sources of calcium
- Semi-skimmed milk (200 ml): approximately 240 mg
- Plain yoghurt (125 g): approximately 200 mg
- Cheddar cheese (30 g): approximately 220 mg
- Tinned sardines with bones (100 g): approximately 350 mg — the bones are the source
- Calcium-set tofu (100 g): 200–350 mg depending on brand (check label)
- Almonds (30 g): 75 mg
- Cooked broccoli (200 g): 80 mg
- Fortified plant milks (200 ml): 240–300 mg (oat, soy, almond — check label for fortification)
- Kale, cooked (100 g): 72 mg — with very high bioavailability despite lower absolute content
Diana's advice: If you're dairy-free, don't overlook fortified plant milks — a 250 ml glass typically provides as much calcium as cow's milk. Always check the label, as fortification varies significantly between brands. Alpro Soya and Oatly Barista, for instance, both provide around 240 mg per 200 ml serving.
Calcium absorption factors
- Vitamin D is essential for intestinal calcium absorption. Without adequate vitamin D, even good dietary calcium intake remains partially ineffective.
- Age: calcium absorption declines with age — an additional reason to optimise intakes after 50.
- Proton pump inhibitors (omeprazole, lansoprazole): long-term use reduces calcium absorption. Discuss this with your GP if you're on these medications.
- Alcohol and caffeine in excess: increase urinary calcium excretion.
A note on supplementation: The evidence on calcium supplements and cardiovascular risk is contested. A meta-analysis by Bolland et al. (BMJ, 2010) suggested that calcium supplements above 500 mg/day outside the diet might increase cardiovascular risk in postmenopausal women. The NHS recommends a food-first approach to calcium, with supplementation only filling proven dietary gaps. If you're supplementing, split doses (no more than 500 mg per dose) and take with food.
Vitamin D: the latitude problem
Vitamin D holds a unique position among micronutrients: it's technically a prohormone, and the majority of us are deficient — particularly in winter. Public Health England data shows that around one in five adults in the UK has low vitamin D levels, with rates significantly higher in winter and among people with darker skin tones, who require longer sun exposure for equivalent synthesis.
The SACN 2016 landmark recommendation
In 2016, SACN (Scientific Advisory Committee on Nutrition) made a landmark recommendation: everyone in the UK should take a 10 micrograms (400 IU) vitamin D supplement daily throughout the year, with particular importance October to March when sun-derived synthesis is insufficient at UK latitudes.
This was a significant shift. The UK sits between 50 and 60 degrees north latitude. From October to March, the angle of solar UVB radiation is too low to enable meaningful cutaneous vitamin D synthesis — even on clear days. In summer, 15–30 minutes of sun exposure to forearms and face (avoiding peak UV hours) is generally sufficient to maintain adequate levels. But summer synthesis does not generate sufficient stores to last the entire winter.
The NHS now actively recommends vitamin D supplementation for:
- All adults October to March
- People with darker skin tones: year-round
- People who cover most of their skin outdoors: year-round
- People who rarely go outside: year-round
- All infants under one year: year-round
Blood test and target values
The relevant blood test is serum 25-OH-vitamin D (25-hydroxyvitamin D). You can request this from your GP, though it may not be automatically offered. Some women order private tests (MonitorMyHealth, Medichecks, etc.) at around £29–£39. Reference values:
- < 30 nmol/L (12 ng/mL): severe deficiency — bone and muscle symptoms possible
- 30–50 nmol/L: insufficiency
- 50–75 nmol/L: adequate (minimum target)
- 75–150 nmol/L: optimal according to many nutrition researchers
- > 250 nmol/L: risk of toxicity
Supplementation in practice
- NHS recommendation: 10 micrograms (400 IU) daily for general population
- For women with confirmed deficiency or at higher risk, GPs may prescribe 800–4,000 IU under supervision
- D3 (cholecalciferol) is significantly more effective than D2 for raising blood levels
- Take with a fat-containing meal to improve absorption (fat-soluble vitamin)
- NHS Healthy Start scheme provides free vitamin supplements including vitamin D for eligible pregnant women and families
Diana's advice: A basic 10 mcg (400 IU) vitamin D3 supplement from October to March costs under £5 for a full winter supply. Brands such as Holland & Barrett, BetterYou oral spray, and Vitabiotics all offer quality options at accessible price points. If you want to know your actual level before supplementing, a home test kit is a reasonable investment — and a useful annual reference point.
Magnesium: the stress and sleep mineral
Magnesium is involved in over 300 enzymatic reactions in the body. Energy production, protein synthesis, nerve and muscle regulation, bone health, blood sugar, blood pressure — it's everywhere. And it's frequently insufficient.
UK NDNS (National Diet and Nutrition Survey) data consistently shows that a substantial proportion of UK women fail to reach the Reference Nutrient Intake (RNI) for magnesium. The RNI is 270 mg/day for women aged 19–64.
Symptoms suggesting a deficit
- Muscle cramps, particularly nocturnal (calves)
- Unexplained fatigue despite adequate sleep
- Irritability, anxiety, nervous tension
- Difficulty falling asleep, poor sleep quality
- Heart palpitations
- Severe premenstrual syndrome (cramps, mood changes, bloating)
- Episodic constipation
Best food sources
- Pumpkin seeds (30 g): 135 mg — the most concentrated source
- Dark chocolate 70%+ (30 g): 52 mg
- Cashew nuts (30 g): 85 mg
- Almonds (30 g): 75 mg
- Sunflower seeds (30 g): 90 mg
- Cooked black beans (100 g): 70 mg
- Cooked quinoa (100 g): 64 mg
- Cooked spinach (100 g): 79 mg
- Banana (medium): 32 mg
Which supplement form to choose
- Magnesium bisglycinate: the best-tolerated and best-absorbed form. Recommended for sensitive digestion and ongoing supplementation.
- Magnesium malate: good bioavailability, often recommended for muscle pain.
- Magnesium citrate: good bioavailability, mildly laxative at higher doses.
- Magnesium oxide: the cheapest and least absorbed form (4–5% only) — avoid as primary supplementation.
Diana's advice: If you're considering magnesium supplementation, start with 200–300 mg of bisglycinate taken in the evening. Magnesium has a relaxing effect and can meaningfully improve sleep quality and stress resilience within a few weeks. For women with severe PMS, supplementation at 300 mg/day from day 15 of the cycle through the start of menstruation has clinical support (Walker AF et al., 1998).
Folate (B9): not just for pregnancy
Folate — vitamin B9 in its natural form, folic acid in its synthetic form — is commonly presented as "the pregnancy vitamin". That reduction does it a disservice: folate is essential for all women at every life stage.
Its primary roles are DNA synthesis and repair, and red blood cell formation. A folate deficiency can cause megaloblastic anaemia — distinct from iron-deficiency anaemia but equally debilitating. It also plays a role in homocysteine metabolism (elevated homocysteine is associated with cardiovascular risk) and cognitive function.
The MTHFR gene: when absorption is genetically compromised
Approximately 40–60% of the European population carries a variant of the MTHFR gene (methylenetetrahydrofolate reductase) that reduces the ability to convert synthetic folic acid into its active form (5-methyltetrahydrofolate, or 5-MTHF). For these individuals, standard folic acid supplements are partially ineffective.
If you have a history of recurrent miscarriages, elevated homocysteine, treatment-resistant depression, or if you're of Northern or Southern European ancestry, MTHFR testing may be worthwhile. The supplement form to prioritise in this case is methylfolate (5-MTHF), which is directly bioavailable.
Requirements and sources
The NHS recommends 200 micrograms (μg) per day for women, rising to 400 μg per day from at least one month before conception through the first 12 weeks of pregnancy. Best food sources:
- Chicken liver (100 g): 590 μg — the richest source
- Edamame / soya beans (100 g): 311 μg
- Raw spinach (100 g): 194 μg
- Asparagus, cooked (100 g): 149 μg
- Cooked lentils (100 g): 181 μg
- Cooked chickpeas (100 g): 172 μg
Note: folate is heat-sensitive. Prolonged cooking destroys a significant proportion. Prefer shorter cooking methods or raw consumption where possible for folate-rich vegetables.
Omega-3: DHA, EPA and the brain
Omega-3 fatty acids are essential polyunsaturated fats — the body cannot produce them and they must come from food. Three types exist:
- ALA (alpha-linolenic acid): found in walnuts, flaxseeds, chia seeds, rapeseed oil. Plant source.
- EPA (eicosapentaenoic acid): found in oily fish. Potent anti-inflammatory.
- DHA (docosahexaenoic acid): found in oily fish and microalgae. Structural component of the brain and retina — 40% of the brain's fatty acids are DHA.
The body can convert ALA to EPA and DHA, but with very limited efficiency: only 5–15% of consumed ALA is converted to EPA, and considerably less to DHA. Marine sources remain essential for maintaining adequate DHA levels.
Why women should pay particular attention
Women have specific DHA needs during reproductive years, particularly during pregnancy and breastfeeding: DHA is actively transferred from mother to foetus and infant for brain development. A breastfeeding woman can transfer up to 100 mg of DHA per day to her baby. Beyond maternity, EPA and DHA play roles in:
- Cardiovascular health: triglyceride reduction, anti-inflammatory effects
- Mental health: robust studies associate EPA and DHA intakes with lower risk of depression, including postpartum depression
- Menstrual cycle regulation: omega-3 reduce production of pro-inflammatory prostaglandins, frequently alleviating period pain
- Skin health: skin hydration and elasticity depend partially on membrane lipids
NHS guidance and sources
The NHS recommends eating at least two portions of fish per week, with one being oily fish. Best sources:
- Mackerel (100 g): 2,600 mg EPA+DHA
- Sardines (100 g): 2,200 mg EPA+DHA
- Salmon (100 g): 2,000 mg EPA+DHA
- Herring (100 g): 1,800 mg EPA+DHA
- Tinned tuna (100 g): 300–600 mg EPA+DHA (variable)
For vegetarians and vegans, microalgae oil (Schizochytrium, Nannochloropsis) is the only direct source of DHA and EPA without an animal origin. Brands such as Bare Biology, Viridian, and Nordic Naturals offer algae-based DHA-EPA capsules widely available in the UK.
Diana's advice: If you're not a fish eater, a daily algae-based omega-3 supplement providing 300–500 mg DHA+EPA is the most evidence-backed approach. It costs approximately £15–£25 per month for a quality product, and the evidence for brain health and anti-inflammatory benefit is strong enough to justify it as a baseline supplement for most women.
Vitamin B12: vigilance for vegetarians and vegans
Vitamin B12 (cobalamin) is the only vitamin absent from the plant kingdom. It's synthesised exclusively by bacteria and found in animal products: meat, fish, eggs, dairy. This makes strict vegetarians and vegans particularly vulnerable.
B12 is essential for red blood cell formation (a deficiency causes megaloblastic anaemia), neurological health (severe deficiency leads to demyelination, a serious complication), and homocysteine metabolism.
The storage paradox
The body stores B12 in the liver for 2–5 years. This is why deficiency can take years to develop in someone who has moved to a vegan diet — and why it's frequently diagnosed late. The first signs — fatigue, memory issues, tingling — are non-specific and easily attributed to other causes.
Relevant blood markers
- Serum B12: standard marker but imperfect — normal values can mask functional deficiency
- Homocysteine: rises when B12 is insufficient (also sensitive to folate and B6)
- Methylmalonic acid (MMA): rises specifically when functional B12 is insufficient — the most specific marker
Methylcobalamin vs cyanocobalamin
Methylcobalamin is the active coenzyme form, directly usable by the body. Cyanocobalamin is cheaper and more stable but must be converted by the body before use — a conversion that may be genetically compromised in some individuals (MTHFR variants, chronic smokers). Methylcobalamin is preferable, especially for ongoing maintenance supplementation.
For vegans, the NHS recommends regular B12 supplementation. A daily dose of 250–500 μg or a weekly dose of 2,000 μg compensates for the low intestinal absorption rate.
Iodine: the underestimated thyroid mineral
Iodine is essential for the synthesis of thyroid hormones (T3 and T4), which regulate metabolism, body temperature, cardiac function, growth, and neurological development. Iodine deficiency is the world's leading preventable cause of thyroid dysfunction.
Women are particularly vulnerable at two life stages:
- Pregnancy: iodine requirements increase by 50% (from 140 to 200+ μg/day) because the foetal thyroid depends on maternal iodine supply until week 16. Deficiency can affect the child's cognitive development.
- Perimenopause: hormonal shifts can amplify underlying thyroid dysfunction, and hypothyroidism is significantly more common in women after 40.
Food sources and the UK context
Unlike France, the UK does not mandate iodised salt. The primary UK dietary sources of iodine are:
- Dairy products (milk, yoghurt): 50–80 μg/100g — the main UK iodine source
- White fish (cod, haddock): 100–200 μg/100g
- Oily fish: 50–100 μg/100g
- Eggs: approximately 20–30 μg per egg
UK vegans who exclude dairy and fish are at significant risk of iodine deficiency. Most plant milks are not iodine-fortified (with the exception of some organic dairy-free alternatives — check the label). The BNF recommends iodine supplementation for vegans and pregnant women who are vegetarian or vegan.
When to request blood tests: symptoms not to ignore
Routine blood tests are not always necessary. But certain symptom combinations or risk profiles warrant a targeted micronutrient panel — and the NHS makes these accessible via GP referral.
Symptoms that suggest deficiency to explore
- Persistent fatigue despite adequate sleep: explore ferritin, TSH thyroid, B12, vitamin D
- Unusual hair loss: ferritin, TSH, zinc
- Recurrent muscle cramps, especially nocturnal: magnesium, calcium, potassium
- Palpitations or breathlessness on exertion: haemoglobin, ferritin
- Tingling in hands or feet: B12, folate
- Repeated winter infections: vitamin D, zinc
- Recurrent winter low mood: vitamin D
- Severe PMS, intense period pain: magnesium, omega-3, vitamin D
Recommended panels by profile
All women, once a year: Full Blood Count (FBC), ferritin, vitamin D (25-OH).
Women of reproductive age with heavy periods: Add full iron studies (serum iron + ferritin + transferrin saturation).
Vegetarian women: Add serum B12 + homocysteine, urinary iodine if concerned.
Vegan women: Add serum B12 + MMA, omega-3 index (if available), urinary iodine, zinc.
Women pregnant or planning pregnancy: Full panel including red cell folate, iodine, omega-3, vitamin D, B12.
Women over 50: Add bone profile (calcium, phosphate, PTH), TSH, B12.
In the UK, you can request these through your GP. Many are covered on the NHS when clinically indicated. Private options (Medichecks, Blue Horizon, Thriva) offer comprehensive women's micronutrient panels from £50–£150 if you prefer faster results or broader panels.
Supplements or food: the food-first philosophy
The foundational principle in nutrition is simple and robustly supported: food first. Whole foods contain not only the target micronutrient, but the full matrix of cofactors, fibre, antioxidants, and bioactive compounds that optimise absorption and utilisation. No supplement replicates this complexity.
This doesn't mean supplements are useless. There are situations where they are not only useful but necessary:
When supplementation is justified
- Biologically confirmed deficiency: low ferritin, insufficient vitamin D, borderline B12 — in these cases, correcting through diet alone typically takes months and remains uncertain.
- Increased requirements that diet cannot reliably cover: pregnancy (folate, iodine, DHA), breastfeeding, very heavy periods.
- Strict dietary restrictions: veganism (B12 mandatory, vitamin D, omega-3 DHA-EPA, iodine if no iodised salt).
- Conditions or medications interfering with absorption: Crohn's disease, bariatric surgery, long-term PPIs, metformin (depletes B12).
- Seasonal context: vitamin D in autumn and winter at UK latitudes — the evidence is solid enough to justify preventive supplementation for the entire population (SACN 2016).
How to choose a quality supplement
- Bioavailable form: bisglycinate over oxide for magnesium, methylcobalamin for B12, D3 for vitamin D, methylfolate for B9 if MTHFR variant.
- Adequate dosage: avoid unjustified mega-doses. A quality supplement gives you what you need, not the maximum possible.
- Third-party certifications: NSF International, Informed Sport, or USP labels confirm that the product contains what's stated. In the UK, look for compliance with EU food supplement directive 2002/46/EC.
- Excipients: avoid artificial colorants, titanium dioxide (TiO2), and excessive fillers. Minimalist formulations are generally a positive signal.
Warning on micronutrient polypharmacy: Taking ten different supplements without medical oversight is not a health strategy. Some interactions are clinically significant: calcium and iron block each other, excess zinc inhibits copper absorption, excess vitamin D is toxic. Targeted supplementation based on proven deficiencies, with regular biological follow-up, is always superior to a "just in case" approach.
FAQ — essential micronutrients for women
Can I know if I'm deficient without blood tests?
Suggestive symptoms exist — persistent fatigue, hair loss, cramps, tingling — but they're non-specific and shared across many conditions. A blood test remains the only reliable way to confirm a deficiency and identify its nature. Self-medicating with supplements without testing can delay a meaningful diagnosis or create iatrogenic imbalances. In the UK, a standard GP appointment with blood test request costs nothing via the NHS — and is a far better investment than months of blind supplementation.
Are vegetarian and vegan diets compatible with good micronutritional status?
Yes, with careful planning and regular monitoring. The most frequent deficiencies in plant-based diets are: B12 (mandatory supplementation for vegans), vitamin D (winter supplementation for everyone in the UK), omega-3 DHA-EPA (microalgae oil), iodine (significant risk in UK vegans given no mandatory salt iodisation), zinc (lower bioavailability from plant sources), and calcium (if dairy excluded). Annual blood monitoring and targeted supplementation support excellent long-term status. Both the BDA (British Dietetic Association) and the NHS recognise that well-planned vegetarian and vegan diets are nutritionally adequate.
Is vitamin D supplementation really necessary for all UK women?
According to SACN's 2016 report, yes — for everyone in the UK from October to March, and year-round for higher-risk groups. The UK's northern latitude means solar UVB is insufficient for vitamin D synthesis for roughly half the year. Dietary sources cover only 10–20% of requirements. Public Health England data shows around one in five adults has low vitamin D levels. A 10 mcg (400 IU) D3 daily supplement from autumn to spring costs under £5 for the season and is supported by the strongest recommendation SACN has made for a single supplement across the general population.
Does iron supplementation cause weight gain or water retention?
No. Iron has no direct effect on weight or fluid retention. However, certain iron supplements — particularly ferrous sulphate — can cause constipation, bloating, and digestive discomfort that creates a sensation of abdominal heaviness. Opting for better-tolerated forms (ferrous bisglycinate, ferrous gluconate) and taking the supplement with a light meal significantly reduces these effects. The fatigue associated with iron deficiency itself may reduce physical activity and indirectly influence weight — treating the deficiency resolves this cycle.
Which micronutrients are most important after 40?
After 40, several dynamics shift: bone mass begins its decline, intestinal absorption of certain nutrients decreases, and thyroid dysfunction risk increases. Micronutrients to monitor particularly carefully are: calcium and vitamin D (bone health), B12 (gastric absorption decreases with age — sublingual forms or injections become more relevant), vitamin D (deficiency risk increases), magnesium (cramps and sleep disturbances are more frequent), and omega-3 (cardiovascular and cognitive protection). Annual blood monitoring is particularly justified from age 45.
Does the menstrual cycle influence micronutrient needs?
Yes — and this is a frequently overlooked aspect. During menstruation: iron losses are maximal — ferritin stores are most heavily solicited at this time. In the luteal phase (second half of the cycle): magnesium requirements increase, explaining frequent premenstrual symptoms. Supplementation of 200–300 mg of magnesium from day 15 through the start of menstruation is supported by controlled studies (Walker AF et al., 1998; De Souza MC et al., 2000). A cyclical nutritional approach — enriched in iron around menstruation, in magnesium during the luteal phase — is an evidence-backed strategy that remains underused in practice.
Can I take all my supplements together in the morning?
This is not optimal for absorption. Key interactions to know: calcium and iron compete at the intestinal level — never take them at the same meal. Vitamin D is fat-soluble and absorbs better with a fat-containing meal. Iron absorbs better on an empty stomach or with vitamin C, but is often better tolerated with a light meal. Magnesium taken in the evening has a relaxing effect and supports sleep quality. A practical structure: iron in the morning with orange juice away from tea and coffee; vitamin D and omega-3 with lunch; magnesium in the evening. A registered dietitian or pharmacist can help personalise this plan to your specific supplementation needs.
Sources and references
- NHS — Vitamins and minerals (2023) — nhs.uk
- SACN — Vitamin D and Health (2016) — gov.uk
- BNF (British Nutrition Foundation) — Micronutrients and women's health — nutrition.org.uk
- Holick MF — Vitamin D Deficiency, New England Journal of Medicine (2007) — nejm.org
- Walker AF et al. — Magnesium supplementation alleviates premenstrual symptoms of fluid retention, Journal of Women's Health (1998) — liebertpub.com
- The Lancet — Global burden of micronutrient deficiencies in women of reproductive age (2022) — thelancet.com