Vitamin D deficiency
symptoms, the NHS list.
Low mood through winter. Bone and muscle ache. Getting ill repeatedly. None of these on its own is a diagnosis, but the NHS lists them as signs to take seriously. We track and surface. We don't diagnose. See your GP if symptoms persist.
The signs,
plain English.
Four patterns the NHS associates with low vitamin D. None is conclusive on its own; a few together are a reason to talk to your GP.
Persistent low mood through winter
Lower energy, lower mood, harder to drag yourself out the door. Often called "the winter dip". Vitamin D plays a role in serotonin synthesis; low levels are linked to low mood in observational research.
Bone and muscle pain or tenderness
Achy hips, lower back, the front of the shins. Sore on pressure. Vitamin D helps the gut absorb calcium; running short over months can leave bones softer and muscles weaker.
Getting ill more often
Repeated chest infections, head colds that won't shift, slow recovery. Vitamin D interacts with the immune system; the NHS lists recurring infections as a possible sign.
Hair feeling thinner
Hair loss can have many causes; vitamin D is one to keep on the list. Not a primary diagnostic, but mentioned in the NHS literature.
10µg a day,
October to March.
The NHS recommends everyone aged four and over consider a daily 10µg vitamin D supplement through autumn and winter. UK UVB drops too low for meaningful skin synthesis between October and March, regardless of time spent outside.
The supplement is 10µg (400 IU)
The everyday UK winter dose. Sold in supermarkets and pharmacies. Vitamin D drops, D3 tablets, sprays. They all reach the same target if dosed daily.
Risk groups year-round
The NHS recommends a daily supplement year-round for people with darker skin (African, African-Caribbean, South Asian backgrounds), people who spend most of the day indoors, and people who cover most of their skin outside.
Children: a separate dose
Breastfed babies under 1 year: 8.5µg to 10µg/day all year. Formula-fed babies on more than 500ml a day don't need a supplement (formula is fortified). Children 1 to 4: 10µg/day all year.
The upper intake limit
Adults: 100µg/day. The NHS sets this; doses above it for long periods can raise calcium to harmful levels. Don't stack the 10µg supplement with a multivitamin and a fortified drink without checking the total.
The numbers,
not the diagnosis.
Log a week. Read the weekly vitamin D average against UK NRV. If it's running short, the pattern is something to take to your GP, alongside the symptoms.
Oily fish is the biggest food source of vitamin D in a UK shop. Sardines and mackerel hit similar.
Eggs are the everyday source. Modest, useful, regular.
UK margarines are required to be fortified with vitamin D. A small contribution per slice.
UK NRV for vitamin D is 5µg/day. The NHS winter recommendation is 10µg/day, double the NRV.
The honest line
on medical territory.
We track. We don't diagnose. There are situations where the GP, not the app, is the next step.
Symptoms persist after four to six weeks
On the 10µg supplement, symptoms should improve over weeks. If they don't, see your GP. The blood test is the test for deficiency; the supplement is the practical first step the NHS recommends.
Bone pain on pressure
Real bone tenderness (lower back, shins, hips) is worth a GP appointment sooner. Could be other things; the GP makes that call.
Pregnancy and breastfeeding
The NHS recommends a daily 10µg supplement in pregnancy and breastfeeding. Speak to your midwife if you're unsure. Iron and iodine are also worth tracking in this window.
Long-term care or housebound
People who spend most of their time indoors, including in care homes, are higher risk. A year-round supplement is the NHS recommendation. Speak to the care team.
Frequently
asked.
From the support inbox.
The NHS associates low vitamin D with persistent low mood (especially in winter), bone and muscle pain or tenderness, getting ill more often, and hair feeling thinner. None on its own is a diagnosis. See your GP if symptoms persist.
The NHS recommends everyone aged four and over consider a daily 10µg vitamin D supplement during autumn and winter (October to March), when UK sunlight is too weak for skin synthesis.
The NHS does not routinely offer blood tests for vitamin D without clinical symptoms. The practical first step is the 10µg daily supplement; see your GP if symptoms persist after four to six weeks.
Even a diet including oily fish twice a week rarely meets the 10µg daily target through a UK winter, once the drop in sunlight synthesis is factored in. That's the honest case for the supplement.
Between October and March, UVB levels in the UK fall too low for skin to produce meaningful vitamin D, regardless of how much time you spend outside. Food and a 10µg supplement fill the gap.
Track your week,
see your vitamin D,
take it to your GP.
Free download. Pro at £3.99 a month or £34.99 a year for the full vitamin and mineral tracker against UK NRV, weekly summary and the AI Coach.
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