Vitamin D Deficiency Symptoms: Signs to Know This UK Winter

By the GUUDIES Editorial Team · Updated 26 October 2026 · Claims checked against the GB Nutrition and Health Claims Register; sources below.

Disclosure: GUUDIES makes a daily gummy pouch that includes vitamin D3. This guide follows NHS advice, which applies whatever product you choose.

The short answer: vitamin D deficiency symptoms in adults can include bone pain (especially in the back, ribs, pelvis or legs), muscle weakness, cramps or twitching, and finding it harder to climb stairs or get out of a chair, though many people with low levels notice nothing at all. Because UK sunlight is too weak to make enough vitamin D from about October to March, the NHS advises everyone to consider a 10µg daily supplement in autumn and winter, and if you have symptoms, see your GP rather than guessing.

Why Vitamin D Runs Low in a UK Winter

Your skin makes vitamin D from sunlight. The NHS says that from about late March or early April to the end of September most people can get enough from sunlight and diet, but in autumn and winter they cannot (NHS). Few foods contain much vitamin D: oily fish, red meat, egg yolks and fortified foods such as some spreads and breakfast cereals. UK cows' milk is generally not fortified.

That is why the government's scientific advisers recommend 10µg a day for everyone aged 4 and over (SACN), and why the NHS advice is to consider a supplement from October to March.

Vitamin D Deficiency Symptoms in Adults

Long-term low vitamin D and calcium can lead to osteomalacia, a softening of the bones. The NHS lists these symptoms (NHS):

Symptom	What it can feel like	Other common causes to rule out
Bone pain	Aching in the back, shoulders, ribs, pelvis or legs	Posture, injury, arthritis
Muscle weakness	Difficulty climbing stairs or getting out of a chair	Inactivity, other medical conditions
Muscle cramps or twitching	Tingling, cramping or twitching	Dehydration, exercise, some medicines
Changes in walking	Tiring more easily when walking, or not wanting to walk much	Joint problems, general fitness
Painful wrists	Swollen, painful wrists	Injury, arthritis
Broken bones	Fractures after a minor fall, especially hips, lower back and feet	Osteoporosis

Tiredness and low mood are often linked to vitamin D online, and winter can certainly feel like a slog. But both have many possible causes, including iron deficiency, thyroid problems, poor sleep and depression. If you feel tired or low most days, see your GP rather than assuming it is vitamin D.

Who Is Most at Risk?

The NHS advises taking 10µg of vitamin D every day all year, not just in winter, if you (NHS):

• are not often outdoors, for example if you are frail, housebound or live in a care home
• usually wear clothes that cover most of your skin when outdoors
• have dark skin, for example if you have an African, African-Caribbean or South Asian background

Office workers, night-shift workers and people who eat no oily fish, eggs or fortified foods may also find it harder to get enough, which is a reason to take the winter advice seriously.

How to Check Your Vitamin D Level

The only way to know your level is a blood test. If you have symptoms such as bone pain or muscle weakness, or you are in a higher-risk group, ask your GP. Private finger-prick tests are also available, but discuss abnormal results with a GP rather than self-prescribing high doses. Read more in our guide to vitamin D blood tests in the UK.

How Much Vitamin D Should You Take?

• For most adults: 10µg (400 IU) a day, at least from October to March.
• Upper limit: do not take more than 100µg (4,000 IU) a day unless a doctor advises it, as long-term excess can raise blood calcium and harm the bones, kidneys and heart (NHS).
• If you are diagnosed as deficient: your GP may prescribe a higher, short-term dose. Follow their plan rather than over-the-counter advice.
• Add it up: multivitamins, fortified foods and separate vitamin D products all count towards your daily total.

Vitamin D contributes to the maintenance of normal bones and normal muscle function, and to the normal function of the immune system. D3 (cholecalciferol) is the form most supplements use.

Is It Worth Starting Before Winter?

Yes, if you plan to supplement at all. Your body stores some vitamin D from summer, but levels fall through autumn. Starting in October, when the clocks change and the NHS advice kicks in, keeps things simple. If you rarely get outdoors in summer either, consider the all-year advice above.

Where GUUDIES Fits

GUUDIES is one daily pouch of six pectin-based gummies for adults. The Daily Greens+ gummy contains 20µg of vitamin D3 (400% NRV), double the NHS 10µg recommendation and well within the 100µg upper limit, plus 80µg of vitamin K2. Vitamin D contributes to the maintenance of normal bones and the normal function of the immune system, and vitamin K contributes to the maintenance of normal bones.

If you already take a separate vitamin D product, add the doses together. If you have been diagnosed as deficient, follow your GP's dosing plan. Five of the six gummies are vegan; Marine Collagen contains fish. Each gummy has about 0.4g of sugar.

See the GUUDIES daily pouch

Common Questions

What are the first signs of vitamin D deficiency?
Many people have no symptoms at first. When symptoms do appear in adults they can include bone or back pain, muscle weakness, cramps and difficulty with stairs. A blood test is the only way to know.

Can low vitamin D make you tired?
Tiredness is commonly linked to low vitamin D, but it has many causes. If you are tired most days, see your GP so other causes can be checked.

When should I start taking vitamin D in the UK?
The NHS advises everyone to consider 10µg a day from October to March. Some people should take it all year round.

How much vitamin D is too much?
Adults should not take more than 100µg (4,000 IU) a day unless a doctor advises it.

Is vitamin D3 better than D2?
Most supplements use D3, and both count towards the NHS recommendation. What matters most is taking 10µg a day consistently.

Sources

• NHS, Vitamin D: nhs.uk
• NHS, Rickets and osteomalacia: nhs.uk
• SACN, Vitamin D and health report: gov.uk
• GB Nutrition and Health Claims Register: gov.uk

Related Reading

How Much Vitamin D Should I Take? · Should You Get a Vitamin D Blood Test? · Vitamin D in the UK: Why Winter Is Different · Tired All the Time? · Vitamin D3 in GUUDIES