Which nutrients for women matter most?
The nutrients for women worth knowing first are iron, calcium, vitamin D and folic acid, and the amounts shift with each stage of life. For adult women, the UK's NHS sets iron at 14.8 mg a day (ages 19 to 49) and calcium at 700 mg (ages 19 to 64) and advises a 10 µg (400 IU) vitamin D supplement in autumn and winter, and in the US the USPSTF recommends 400 to 800 mcg of folic acid a day for anyone who could become pregnant.
Wondering whether you get enough of a nutrient is common, and it's normal for the answer to change as your body does. This index holds one page for each of seven nutrients: the four above, plus fiber, protein and omega-3. Each puts food first, with US amounts and metric and UK values alongside. By stage: for the early years, there is childhood nutrition. For first periods and fast growth, there is nutrition in puberty. Anyone planning or expecting a baby may like a balanced pregnancy diet. For the lead-up to menopause, perimenopause weight gain is written around strength and how you feel. The years around the final period have menopause weight gain, and later life has postmenopause weight gain. Those three also cover how calcium and iron needs shift in midlife and after.
- Fiber: High fiber foods and the daily fiber targets at each age.
- Vitamin D: Who may like a supplement, how sunlight fits in, and how US and UK advice differ.
- Omega-3: Oily fish first, and what the evidence says about omega-3 supplements.
- Folic acid and folate: Folic acid for anyone who could become pregnant, and where folate shows up in food.
- Calcium: Food sources first, and how to space a calcium supplement if your diet falls short.
- Protein: Daily protein in grams per kilogram, and when very active girls and women may need more.
- Iron: Why needs rise once periods start, how ferritin testing works, and how to pair plant iron with vitamin C.
Facts
Common questions
Do I need supplements, or is food enough?
Food is a good place to start, and the evidence supports adding a supplement only where there is a gap. Calcium is taken as 500 mg or less per dose, and iron follows a blood test showing low stores. A dietitian can help with dairy-free eating.
How can I tell whether my iron is low?
Low iron is common and treatable, especially once periods start. Tiredness and poor concentration are the usual signs, and heavy periods make it more likely. A sensible first step is asking a doctor (a GP in the UK) for a ferritin test and a blood count; iron is then taken as prescribed.
Why take folic acid before pregnancy?
Neural tube defects form in the first few weeks of pregnancy, often before a woman knows she is pregnant. That timing is why folic acid is advised before pregnancy, even when it isn't planned, rather than after a positive test. A doctor or pharmacist can help you choose a dose.
Is vitamin D needed all year in the UK?
In the UK, the NHS advises the supplement from about October to early March for everyone aged 1 and over, and all year for some groups, including people with dark skin, people who cover most of their skin outdoors and people who are rarely outside. US guidance for teens points to a supplement when blood levels are low or sun is scarce.
What do IU, mcg and µg mean on a label?
IU stands for international units, while mcg and µg both mean micrograms. 400 IU is 10 µg and 600 IU is 15 µg, so a UK 10 µg supplement and a US 400 IU one hold the same amount. Iron and calcium are given in milligrams (mg) in both countries.
What do vegan diets need to watch?
Vitamin B12 is essential on a vegan diet, from fortified foods or a supplement. Many vegans also plan for reliable iodine, calcium and omega-3. Plant milks are often unfortified, so a look at the label is worthwhile, and a dietitian can build a plan around foods you like.
Next steps
A good place to start is the nutrient page that matches your question, or the stage page that matches where you are now. If periods are heavy, tiredness lingers, or you eat vegan or dairy-free, a doctor (a GP in the UK) or a dietitian can turn general targets into a plan that suits you. Nutrition is not one size fits all, so take what fits your body, your stage and your food preferences.
Sources
The guidelines and studies this page draws on.
- Folic Acid for the Prevention of Neural Tube Defects: Preventive Medication, USPSTF (2023)
- Folic acid, CDC (n.d.)
- Vitamin D, NHS (n.d.)
- Iron, NHS (n.d.)
- Calcium, NHS (n.d.)
- Calcium, iron and vitamin D intakes, NIH Office of Dietary Supplements (n.d.)
- National Osteoporosis Foundation position on peak bone mass (Weaver et al.), Osteoporosis International (2016)
- Bright Futures guidelines for adolescent well visits, American Academy of Pediatrics (n.d.)