The headline numbers
According to the NHS, women aged 19 to 49 need 14.8mg of iron a day. Once you reach 50, the requirement drops to 8.7mg, the same figure men need at any age.
You may have seen 18mg quoted on American websites or supplements imported from the US. That is the US Recommended Dietary Allowance, not the UK figure. The NHS and the UK Nutrient Reference Values use 14.8mg for women in the pre-menopausal years. If you are using a supplement and the label shows 18mg as the target, it is calibrated to a different system.
Why women specifically
The higher requirement for younger women is not arbitrary. Menstruation means iron loss every month, and the body has to replace it. Men do not have this cycle, which is why their target stays at 8.7mg throughout adulthood. Women pre-menopause are essentially running with a higher baseline demand than men of the same age.
The BDA notes that females aged 11 to 50 need 14.8mg, with the figure dropping to 8.7mg after the menopause. The biology lines up with the numbers: once monthly blood loss stops, the requirement equalises with men.
Pregnancy and breastfeeding
Pregnancy is where the picture gets more individual. The NHS advises that most women in the UK do not need to routinely take iron supplements during pregnancy if they are eating a varied diet. However, if symptoms suggest low iron, the right step is to speak to your midwife or GP rather than to self-prescribe. High-dose iron supplements are not something to take without a blood test and clinical guidance.
Breastfeeding has a different profile again. If you have questions about iron during breastfeeding, the NHS and your health visitor are the right places to start rather than a general guide.
Intake is not the same as absorption
This is the part most general articles skip over, and it matters. Eating 14.8mg of iron does not mean 14.8mg reaches your bloodstream. How much you absorb depends on the type of iron and what else you eat with it.
Iron comes in two forms. Haem iron, from meat and fish, is absorbed at roughly 25%. Non-haem iron, the form found in plant foods, is absorbed at somewhere between 5% and 10%. The 14.8mg target is set with typical absorption rates in mind, so it already accounts for the fact that not all of it will get through. But if most of your iron comes from plant sources, your body may be absorbing only a fraction of what you eat.
A few pairing habits help. Eating plant-based iron alongside vitamin C, such as a glass of orange juice with lentils or a squeeze of lemon over spinach, improves absorption of non-haem iron. Having tea or coffee within an hour of a meal can block it, so it is worth keeping those apart from your main iron-rich meals, particularly if you rely on plant sources.
What 14.8mg looks like in actual food
Lean beef, lentils, cooked spinach, and fortified cereals are the four sources most women lean on. Getting to 14.8mg across a day is achievable, but the detail matters: which foods pair well with vitamin C, when to skip the tea or coffee, and how much a typical portion actually contributes. We go into all of that in the foods high in iron for women guide.
Signs you might be running low
Tiredness, breathlessness on the stairs, and looking paler than usual are the most common early signs. If those persist after a few weeks of paying more attention to iron-rich foods, a GP visit is the right next step, they can run a full blood count to confirm. The full symptom pattern and what each one means is covered in the iron deficiency symptoms guide.
A short, honest note
This is general information, not clinical advice. If symptoms persist, see your GP.