How much vitamin D do women need?
Most teenage and adult women need about 600 IU (15 µg) of vitamin D a day in the US and 10 µg (400 IU) a day in the UK. It is one of the nutrients for women where the figure shifts a little with life stage, and a vitamin D supplement tends to matter most when sun, skin tone or a blood test points to a gap.
If you are wondering whether you get enough, you are in good company: it is common to be unsure, and for most women the answer is a modest daily amount, not anything complicated. Vitamin D is a vitamin your skin makes when sunlight reaches it, and it also comes from a few foods and from supplements. It is normal for US and UK advice to read a little differently, so both sit side by side here.
What is vitamin D and where does it come from?
Vitamin D reaches the body three ways: sunlight on skin, food and supplements. Fortified milk, oily fish and eggs are the everyday food sources. A vitamin D supplement, sometimes labeled supplemental vitamin D, tops up what sun and food already provide.
Amounts appear in two units, which is a common source of confusion. US labels use international units (IU) and UK labels use micrograms (µg, also written mcg): 400 IU is 10 µg, 600 IU is 15 µg and 800 IU is 20 µg.
What does the evidence say about vitamin D and women's health?
For most women vitamin D is a quiet, background nutrient, and the evidence behind it is reassuringly simple. Its clearest role is in bone health, where it works beside calcium and regular heavy and impact exercise, not on its own. For women being treated for osteoporosis, it is often given with calcium alongside bone medicines when dietary calcium is low.
The case for vitamin D supplementation is strongest when there is a gap to fill. The NIH Office of Dietary Supplements intake guidance rates the evidence as strong when a blood level is low, and it gives the daily figures used on this page.
Running low is common, and it reflects circumstances, not anything a woman has done. Darker skin, skin that is usually covered and little time outdoors are the reasons the same guidance gives for checking a level, and the NHS names similar groups. A blood test is how a low level is confirmed, so it's worth asking about one if any of these apply to you.
How much vitamin D, and how often?
For teenagers and women in the reproductive years the US figure is 600 IU (15 µg) a day. In the UK the NHS figure is 10 µg (400 IU) a day at every age from 1, all year round. What changes with the season is the supplement, which everyone is invited to consider in autumn and winter and through pregnancy and breastfeeding.
Through perimenopause and menopause the US range is 600–800 IU (15–20 µg) a day. After menopause it is 600 IU to age 70 and 800 IU from 71, while the UK stays at 10 µg, the year-round amount the Scientific Advisory Committee on Nutrition (SACN) set in 2016.
A higher amount, 1,000–2,000 IU a day, also appears in the NIH Office of Dietary Supplements intake guidance for perimenopause, especially for winter. It is an amount for correcting a low level found on a blood test, not a routine target for everyone.
Vitamin D supplements are often prescribed together with a calcium supplement when diet falls short, and the prescription then sets the amount. When trying to conceive and in pregnancy, prenatal vitamins usually contain vitamin D already, so the label will show whether a separate one would double up.
When to see a doctor. It's worth a conversation with a healthcare provider (in the UK, a GP) if you are in one of the groups more likely to run low, if a blood test has come back low, if you are thinking about taking more than the amount for your stage, or if you are being treated for bone loss.
What did the studies show, and what did they not show?
One study explains why vitamin D gets more attention in midlife. The Study of Women's Health Across the Nation (SWAN), reported by Greendale and colleagues in 2012, followed women's bones through the menopause transition. It found that bone changes most quickly, by about 2% a year, around the final period and the first years after it. That is a normal part of the transition, and it shows when looking after bone pays off most.
What SWAN did not show is that vitamin D alone keeps bone steady. It is named beside HRT, heavy and impact loading and calcium, so it reads best as one gentle support among several. The midlife amounts are also ranges, not single numbers, which is why two women of the same age can sensibly settle on different amounts.
Vitamin D by life stage
| Stage | Figure | Why | Read more |
|---|---|---|---|
| Childhood | 400 IU (10 µg) a day from birth for breastfed and partly breastfed babies; UK 10 µg (400 IU) | Included for mothers: breastfed babies need a supplement from birth, and the childhood page covers the detail. | Nutrition |
| Puberty | 600 IU (15 µg) a day; UK 10 µg a day, with a supplement considered in autumn and winter | Most teenagers need no other supplement; this one fills the gap when sun is limited or skin is darker. | Nutrition |
| Reproductive years | 600 IU (15 µg) a day; UK 10 µg a day, with a supplement considered in autumn and winter and through pregnancy | Testing is offered to women more likely to run low, not to everyone. | Nutrition |
| Perimenopause | 600–800 IU a day; 1,000–2,000 IU for many with a low level, especially in winter | The higher range is for correcting a low blood result, followed by a recheck. | Nutrition |
| Menopause | 600–800 IU (15–20 µg) a day; more if low | Bone changes most quickly around the final period, so vitamin D joins calcium and impact exercise. | Nutrition |
| Postmenopause | 600 IU to age 70, 800 IU from 71; UK 10 µg a day year-round | A daily supplement suits women who spend much of the day indoors, taken as prescribed where calcium is given with it. | Nutrition |
Guidance by country
Facts
Common questions
Do I need a blood test for vitamin D?
Not everyone does. A test is most useful if you are in one of the groups more likely to run low. A result under 20 ng/mL, which is 50 nmol/L in the units UK labs use, counts as low. If you start supplementing vitamin D after a low result, a recheck shows whether it has worked. A healthcare provider (in the UK, a GP) can arrange both.
Is there an upper limit for vitamin D?
Yes, and it is reassuringly far above everyday amounts. The NHS gives a safe upper limit of 100 µg (4,000 IU) a day for adults, including in pregnancy and breastfeeding, and for ages 11–17. Every stage figure on this page sits well below that, so the limit mostly matters when several products are taken together. If you are unsure what yours add up to, a pharmacist can help you total them.
Can sunshine alone cover my vitamin D?
Sunshine counts, most of all in summer, and sun protection still belongs alongside it. Daily time outdoors where possible is a good place to start. It is common for sun to fall short for part of the year, so many women treat it as one of three sources and lean on food or a supplement in the months when they are outdoors less.
Do I need extra vitamin D in pregnancy?
Usually not extra, just steady. The US figure stays at 600 IU (15 µg) a day, and UK advice is 10 µg a day through pregnancy and breastfeeding. A prenatal vitamin chosen when trying to conceive normally includes vitamin D with folic acid and iodine, so one product often covers it. Your midwife or pregnancy care provider can check the label with you at an early visit.
Should I take vitamin D all year or only in winter?
For many women the colder months are enough, but some are invited to continue all year. The NHS suggests 10 µg a day year-round for people who are not often outdoors, such as those who are frail or housebound, people in care homes, people who usually cover most of their skin outdoors and people with dark skin.
Next steps
A good place to start is the figure for your own stage in the table above, set against what you already get: fortified milk, oily fish and eggs, time outdoors, and the vitamin D line on any multivitamin label. If you are in a group more likely to run low, a blood test with your healthcare provider (in the UK, your GP) turns a guess into a number. From there the amount, the season and whether to supplement at all are yours to weigh: not one size fits all.
Sources
The guidelines and studies this page draws on.
- Vitamin D – NHS (vitamins and minerals), NHS (UK) (2020)
- SACN vitamin D and health report, UK Government / SACN (2016)
- Greendale et al.: bone loss across the menopause transition (SWAN), Journal of Bone and Mineral Research (2012)