Learn

Nobody warns you about the second week. You start the iron, feel quietly virtuous, and then your stomach files a complaint: cramps, queasiness, a bathroom schedule that has stopped being yours. The NHS lists constipation or diarrhoea, tummy pain, heartburn and feeling sick as the usual suspects, plus darker-than-usual poo.[1] Its advice is oddly blunt: keep taking the tablets anyway.[1]Easier said than done. So here's what genuinely makes a difference, and what's just folklore.It isn't just youIf iron upsets your stomach, you're in good company. A 2015 systematic review in PLOS ONE pooled 43 randomised trials and 6,831 adults and found that ferrous sulfate significantly raised the odds of gastrointestinal side effects compared with placebo.[2] 2.32 Odds ratio for gastrointestinal side effects with ferrous sulfate versus placebo, across 43 trials One caveat: that review looked at ferrous sulfate, the standard prescription form, so it can't tell you how any other form compares. Take it as proof that iron upset is real and common, not as a character flaw.Look at the dose firstThe NHS says 17mg a day or less of iron from supplements is unlikely to cause harm, and it names constipation, nausea, vomiting and stomach pain as side effects of higher doses, over 20mg.[3] For context, adult women aged 19 to 49 need 14.8mg a day, while men and women over 50 need 8.7mg.[3]So if a high-dose tablet is wrecking your week, it's worth a word with your pharmacist or GP. And if a GP prescribed it for a diagnosed deficiency, don't swap anything yourself; that's their call.For everyone else who simply wants to top up, a lower daily dose is the obvious thing to try first. Oxford Origins' Vegan Iron Complex sits at 14mg of iron per capsule as ferrous fumarate, under that 17mg line, alongside 400mcg of folic acid and 100mcg of vitamin B12.The Golden Pick Vegan Iron Complex with Vitamins C, B12 & Folic Acid 14mg iron (ferrous fumarate) · 400mcg folic acid · 100mcg B12 · vegan £9.95● OUT OF STOCK View Vegan Iron Complex →Food, timing and what's in your cupThis is where most of the easy wins live. The NHS says taking iron tablets with or soon after food may reduce side effects, and that a glass of orange juice afterwards may help your body absorb the iron.[1] It also flags large amounts of tea, coffee, milk and dairy as things that make iron harder to absorb, along with high-phytic-acid foods such as wholegrain cereals.[1]Put those together and the classic breakfast of strong tea, porridge and a splash of milk is, annoyingly, the worst slot for your iron. A piece of toast, a glass of juice and a quick tea an hour or two later is kinder on both counts.There's a trade-off, and it's worth being straight about it. Some people take iron on an empty stomach in the hope of absorbing more. If your stomach objects, food is the NHS-backed fix, and an iron tablet you can actually keep taking beats a theoretically better one you abandon on day nine.Does every-other-day dosing help?You may have seen this one. A small crossover study published in Haematologica gave iron-deficient, mildly anaemic women aged 18 to 45 ferrous sulfate tablets on consecutive days and on alternate days, using 100mg and 200mg doses, and found that absorption was greater with alternate-day dosing.[4]Read that carefully, though. It measured absorption, not stomach comfort, and the doses were far above anything in a daily supplement. It's an interesting finding rather than a rule, and if you've been prescribed iron, the schedule is something to settle with your GP.Get tested before you startThe least glamorous tip is the most useful. The NHS says iron tablets are recommended after a blood test shows low red blood cell levels, and that the cause should be identified first.[5] Taking iron you don't need is a reliable way to collect side effects with no upside. If you're not sure whether you're in that camp, our guide on who actually needs to supplement with iron is a good place to start.Then keep a note for a week: what you took, what you ate with it, how your stomach felt. Patterns show up fast. For us, gold standard includes a dose you can stick to, and our Vegan Iron Complex is built around exactly that idea.Frequently asked questionsShould I take iron on an empty stomach or with food?The NHS suggests taking iron tablets with or soon after food if they upset your stomach, as this may reduce side effects. Some people prefer an empty stomach, but if you get nausea or cramps, food is the simplest thing to try first.Why does iron make my poo dark?Darker-than-usual poo is listed by the NHS as a recognised side effect of iron tablets. If you're worried, or it comes with other symptoms, ask your pharmacist or GP.How much iron is safe to take every day?The NHS says 17mg or less a day from supplements is unlikely to cause harm, and only to take more if a GP advises it. If you're unsure whether you need iron at all, read who actually needs to supplement with iron and speak to your GP.Should I stop taking iron if it gives me side effects?The NHS advice is to keep taking the tablets even if you get side effects, and to try taking them with or soon after food. If the side effects don't settle, talk to your pharmacist or GP rather than stopping on your own, particularly if the iron was prescribed.Sources NHS — iron tablet side effects, taking them with food, orange juice, and tea/coffee/milk/wholegrain absorption advice. https://www.nhs.uk/conditions/iron-deficiency-anaemia/treatment/ Tolkien Z et al., PLOS ONE 2015 — systematic review and meta-analysis of gastrointestinal side effects of ferrous sulfate (43 trials, 6,831 adults; OR 2.32 vs placebo). https://doi.org/10.1371/journal.pone.0117383 NHS — iron recommended daily amounts, 17mg supplement guidance and side effects at higher doses. https://www.nhs.uk/conditions/vitamins-and-minerals/iron/ Stoffel NU et al., Haematologica 2020 — iron absorption from supplements greater with alternate-day than consecutive-day dosing in iron-deficient anaemic women. https://haematologica.org/article/view/9379/68313 NHS — iron deficiency anaemia: blood testing and identifying the cause before iron tablets. https://www.nhs.uk/conditions/iron-deficiency-anaemia/ At Oxford Origins, your wellbeing is our priority, and although we pride ourselves on our expertise in nutrition and supplementation, it's important to acknowledge the individuality of each person. Articles published by Oxford Origins are not intended to treat, diagnose, cure or prevent any disease, or replace the advice of your GP. We always recommend consulting with a healthcare provider if you encounter any health concerns, and we'll always be here to support you so you're never alone on your journey.

You've been tired for weeks. Not the normal kind — the kind a full night's sleep doesn't touch, where the stairs feel steeper than they used to, where a session at the gym leaves you flattened for the rest of the day. Before you reach for another supplement, it's worth asking a more specific question: is this iron? Iron deficiency is one of the most common nutritional gaps in the UK, and women carry most of that burden — not through any fault of their own, but because of what their bodies do every month. Here's what the evidence actually shows about the signs, who's genuinely at risk, and when supplementing helps versus when it's papering over something only a blood test would catch. The signs worth mentioning to your GP Iron deficiency builds slowly, which is exactly why it's easy to write off as "just being busy" or "getting older." The NHS lists a fairly specific set of symptoms, and a handful come up often enough to be worth naming directly.[1] Fatigue that doesn't lift with rest — the most common complaint, and the easiest one to dismiss. Paler skin, breathlessness or heart palpitations — signs your blood is carrying less oxygen than it should. Hair shedding more than usual, or spoon-shaped nails — visible changes that often get blamed on stress first. Restless legs, or an odd craving for non-food items like ice — less common, but specific enough to flag to a GP by name. Why this lands on women specifically The UK Reference Nutrient Intake for iron is 14.8mg a day for menstruating women aged 19 to 49, against 8.7mg for men and postmenopausal women — the widest sex-based gap in any standard nutrient table, and it exists for one plain reason: monthly blood loss.[2] We've written before about how few nutrients actually justify a separate "women's" formula — iron is the one that genuinely does. Heavy periods, known clinically as menorrhagia, are — alongside pregnancy — the leading cause of iron deficiency anaemia in women of reproductive age, according to the NHS.[1] The numbers bear that out. A recent analysis of the National Diet and Nutrition Survey found that around one in five UK women of reproductive age are iron deficient, with more than a quarter falling short of the lower reference nutrient intake in their diet altogether.[3] 1 in 5 UK women of reproductive age estimated to be iron deficient, per National Diet and Nutrition Survey data What a blood test actually tells you Here's the part that's easy to skip: you can't diagnose iron deficiency from symptoms alone, and guessing wrong in either direction has consequences. A GP will usually run a full blood count — no special preparation needed — to check your red blood cell levels before recommending anything.[1] If the cause isn't obvious, they may look further, including checking for blood loss elsewhere in the body. This matters because treatment for a confirmed deficiency looks different from general maintenance. NHS-prescribed iron tablets for anaemia are typically taken for around six months and dosed considerably higher than what you'd find in a daily supplement — because they're correcting a measured shortfall, not topping up a borderline diet.[1] Topping up a gap versus treating a diagnosis If your blood test comes back normal but you know your diet runs light on iron — little red meat, not many pulses, or a heavy training schedule that increases iron turnover — a lower-dose daily supplement is a reasonable way to close that gap. That's a genuinely different job to correcting a diagnosed deficiency, and the label should reflect it. This is where a capsule dosed close to the reference intake does more good than a mega-dose you don't need. Our Vegan Iron Complex delivers 14mg of iron as ferrous fumarate, alongside 400mcg of folic acid and 100mcg of vitamin B12 — sitting close to the 14.8mg figure above rather than overshooting it. The Golden Pick Vegan Iron Complex 14mg Iron · Folic Acid & B12 · 120 Capsules £9.95● OUT OF STOCK View Vegan Iron Complex → Iron contributes to the normal formation of red blood cells and haemoglobin, to normal oxygen transport around the body, and to the reduction of tiredness and fatigue — all EFSA-authorised claims, and all reasons the mineral matters day to day, not just when a blood test flags a problem.[4] One caution worth taking seriously: iron isn't a supplement to take "just in case." Unlike most vitamins, the body has no efficient way to get rid of excess iron, so taking more than you need — especially over years — can let it build up to damaging levels. The NHS describes this build-up, known as iron overload, most commonly in the context of haemochromatosis, a genetic condition affecting the liver, joints and heart — but the underlying mechanism is the same reason unnecessary, indefinite iron supplementation isn't something to do casually.[5] This is one supplement where more is not automatically better, and it isn't something men or postmenopausal women should take routinely without a specific reason. The gold standard here is a blood test first Becoming the standard, in this case, isn't about finding the strongest supplement on the shelf. It's about matching the dose to the actual gap, and knowing when "I'm always tired" deserves a blood test rather than a guess. If your diet's the issue, a sensible daily amount is worth keeping in the cupboard. If your body's telling you something more specific is going on, that's a conversation for your GP — not the supplement aisle. Frequently asked questions How long does it take for an iron supplement to work? For a confirmed deficiency, NHS guidance is to expect around six months of treatment before iron stores fully recover, even though tiredness and other symptoms often start easing within a few weeks.[1] For a general dietary top-up rather than a diagnosed shortfall, there's no fixed timeline — it depends on how large the gap was to begin with. Can you take iron supplements every day, long-term? Only if there's a genuine reason to. A low-dose daily supplement to cover a dietary gap is generally considered low-risk for someone who needs it, but iron shouldn't be taken indefinitely "just in case" — excess iron builds up in the body rather than being excreted, and unnecessary long-term use has been linked to iron overload.[5] If you're not sure whether you need it, a blood test settles the question. What's the difference between iron deficiency and iron deficiency anaemia? Iron deficiency means your iron stores are running low. Anaemia is what happens once that shortfall is severe enough to reduce your red blood cell count and affect how well oxygen moves around your body. You can be iron deficient without yet being anaemic, which is part of why a blood test — not symptoms alone — is how a GP tells the two apart. Do vegetarians and vegans need more iron? Not necessarily more, but the iron in plant foods (non-haem iron) is absorbed less efficiently than the iron in meat (haem iron), so vegetarians and vegans often need to pay closer attention to hitting the same RNI figure. Pairing iron-rich plant foods with vitamin C — a glass of orange juice alongside a lentil dish, for example — measurably improves how much of it your body actually absorbs. Sources NHS — Iron deficiency anaemia: symptoms, causes, diagnosis and treatment. nhs.uk/conditions/iron-deficiency-anaemia British Dietetic Association — Iron Food Fact Sheet, Reference Nutrient Intake figures. bda.uk.com/resource/iron-rich-foods-iron-deficiency PMC/NIH — Association between Adiposity and Iron Status in Women of Reproductive Age: Data from the UK National Diet and Nutrition Survey (NDNS) 2008–2019. pmc.ncbi.nlm.nih.gov/articles/PMC11522960 EFSA NDA Panel — Scientific Opinion on the substantiation of health claims related to iron. EFSA Journal 2010;8(10):1740. efsa.onlinelibrary.wiley.com/doi/10.2903/j.efsa.2010.1740 NHS — Haemochromatosis: overview, symptoms and complications of iron overload. nhs.uk/conditions/haemochromatosis At Oxford Origins, your wellbeing is our priority, and although we pride ourselves on our expertise in nutrition and supplementation, it's important to acknowledge the individuality of each person. Articles published by Oxford Origins are not intended to treat, diagnose, cure or prevent any disease, or replace the advice of your GP. We always recommend consulting with a healthcare provider if you encounter any health concerns, and we'll always be here to support you so you're never alone on your journey.

Vitamin B12 deficiency is common in vegans and vegetarians because the body doesn't absorb it easily. Here's how much you actually need, and why.

Two nutrients genuinely differ by sex in UK guidance — iron and folic acid. Here's what actually changes, and what's mostly just marketing.