Vitamin D deficiency is common in the UK, particularly during autumn and winter when sunlight is weak. Low levels of vitamin D can cause vague symptoms like tiredness and aching muscles, but they can also lead to serious bone problems and may be associated with other long‑term conditions. This article explains how to recognise vitamin D deficiency, outlines the health risks and risk factors specific to the UK and provides guidance on when to get tested. Internal links point to related articles that explore each topic in more detail.

Table of Contents

Symptoms of Vitamin D Deficiency

Many people with vitamin D deficiency have no obvious symptoms. Others experience mild, non‑specific complaints that can easily be overlooked. Knowing what to look for can help you identify a potential deficiency.

General Symptoms

Tiredness and low energy – Feeling fatigued or “run down” without a clear cause is a common early sign[1].
General aches and pains – Diffuse bone or muscle pain, especially in the lower back, hips, legs or ribs, may indicate deficiency[2].
Muscle weakness – Difficulty climbing stairs or rising from a chair can be caused by proximal muscle weakness[3].
Bone pain – Persistent bone pain in the ribs, pelvis or legs suggests osteomalacia (softening of the bones)[2].
Mood changes – Low vitamin D status has been linked to depression and low mood, particularly in winter. While evidence is still evolving, supplementation may improve mood in some people.
Frequent infections – Vitamin D plays a role in immune regulation; low levels may contribute to recurrent colds and infections.

Symptoms in Children

Children with deficiency may develop rickets, a condition characterised by soft and weak bones. Symptoms include:

Soft or bowed bones – Legs may appear curved or bow‑legged[4].
Delayed growth and tooth development – Poor growth and late eruption of milk teeth[5].
Irritability and muscle spasms – Irritability or unexplained fussiness may occur[6]. Severe deficiency can cause muscle spasms or seizures due to low calcium levels[7].

Severe Symptoms and Complications

In very severe cases, vitamin D deficiency leads to hypocalcaemia, which can cause:

Muscle cramps and spasms – Painful muscle contractions[8].
Seizures – Particularly in infants and young children[9].
Heart problems – A weakened heart muscle (cardiomyopathy) can develop in extreme deficiency[10].

Anyone with severe symptoms should seek urgent medical attention. For most people, symptoms of deficiency are mild but persistent, making testing and treatment important.

Health Conditions Linked to Low Vitamin D

Osteomalacia and Rickets

Vitamin D is essential for calcium and phosphate absorption, so a prolonged deficiency causes osteomalacia in adults and rickets in children. Osteomalacia presents with bone pain (often in the lower back, hips and legs), muscle weakness and an increased risk of fractures. Rickets leads to soft bones, skeletal deformities, delayed growth and dental problems. In the UK, rickets remains more common among children of South Asian, African and African‑Caribbean heritage[11].

Osteoporosis and Fractures

Insufficient vitamin D increases the risk of osteoporosis, a condition where bones become porous and fragile. The NICE Clinical Knowledge Summary notes that low vitamin D levels are linked to an increased risk of osteoporosis, falls and fragility fractures[12]. Ensuring adequate vitamin D helps maintain bone density and reduces fracture risk, especially in postmenopausal women and older adults.

Muscle Weakness and Falls

Vitamin D receptors in muscle cells support muscle function. Deficiency can cause proximal muscle weakness, leading to difficulty walking or climbing stairs. The NICE summary states that osteomalacia may present with muscle pain, weakness and a waddling gait[13]. Weak muscles contribute to an increased risk of falls and fractures in older adults[12].

Secondary Hyperparathyroidism

When vitamin D levels are low, the parathyroid glands produce more parathyroid hormone (PTH) to maintain blood calcium. Chronic elevation of PTH causes bone resorption, further weakening bones and contributing to osteoporosis. This condition is known as secondary hyperparathyroidism.

Potential Associations with Chronic Diseases

Research has linked low vitamin D status to various health conditions, including cardiovascular disease, type 2 diabetes, autoimmune disorders (such as multiple sclerosis) and certain cancers. These associations do not prove that deficiency causes these diseases; however, maintaining adequate vitamin D levels is considered part of an overall healthy lifestyle. Always consult your doctor if you have questions about chronic disease risk.

Risk Factors in the UK

Limited Sun Exposure

The UK is situated at a high latitude, so sunlight is insufficient to generate vitamin D between October and early March[14]. People who spend most of their time indoors, live in care homes or hospitals or routinely cover their skin (for cultural or health reasons) are at higher risk of deficiency[15]. Even in summer, wearing high‑SPF sunscreen and protective clothing reduces vitamin D synthesis.

Darker Skin and Ethnicity

Individuals with darker skin (African, African‑Caribbean or South Asian) have more melanin, which reduces the skin’s ability to produce vitamin D. The UK Office for Health Improvement and Disparities advises people with dark skin to take a vitamin D supplement year‑round[15]. Rickets is more prevalent among these groups[11].

Age

Older adults produce less vitamin D in their skin and often spend less time outdoors. Ageing also reduces the kidneys’ ability to convert vitamin D into its active form. Adults aged 65 and over are therefore at higher risk and are advised to take supplements year‑round[16].

Pregnancy and Breastfeeding

Pregnant and breastfeeding women need extra vitamin D for the health of both mother and baby. Deficiency during pregnancy may affect the developing foetus and increase the baby’s risk of skeletal problems. Women who have had several babies with short gaps between pregnancies are especially susceptible[17].

Medical Conditions and Medications

People with malabsorption disorders (such as Crohn’s disease or coeliac disease), liver or kidney disease and obesity may struggle to absorb or metabolise vitamin D[18]. Certain medications (anticonvulsants, anti‑HIV drugs and glucocorticoids) increase vitamin D breakdown[19].

Obesity

Vitamin D is fat‑soluble and can be sequestered in body fat, reducing its bioavailability. The NICE summary lists obesity as a risk factor for deficiency[20].

When to Get Tested

Routine testing of vitamin D levels is not recommended for everyone. Instead, testing is advised when clinical signs or risk factors suggest deficiency. According to NICE, healthcare professionals should arrange a serum 25‑hydroxyvitamin D test if a person has[21]:

Musculoskeletal symptoms that may be attributable to vitamin D deficiency – such as widespread bone or muscle pain, proximal muscle weakness or a waddling gait.
Suspected bone disease (osteomalacia or osteoporosis) that may improve with vitamin D treatment.
Known bone diseases like osteoporosis or Paget’s disease, where vitamin D deficiency should be corrected before starting specific treatment.

Your GP may also recommend testing if you are at high risk (e.g., dark skin, frail or housebound, pregnant) or if you have been diagnosed with conditions affecting vitamin D absorption. Testing involves a simple blood test measuring serum 25‑OH D. Results are categorised as follows[22]:

< 25 nmol/L – Deficient; treatment required.
25–50 nmol/L – Insufficient; supplementation advised.
> 50 nmol/L – Sufficient for most people.

What to Do If You’re Deficient

If your test indicates deficiency, your may prescribe a loading dose of high‑strength vitamin D to replenish stores quickly, followed by a maintenance dose of 10 µg per day[23]. Treatment regimens vary depending on severity, age, body weight and underlying conditions. You may also be advised to increase dietary calcium, engage in weight‑bearing exercise and address any contributing medical issues. Follow your doctor’s instructions and arrange follow‑up tests if recommended.

Prevention and Lifestyle Tips

Take a daily vitamin D supplement – In the UK, the government recommends that everyone consider taking 10 µg (400 IU) of vitamin D daily during autumn and winter[24], and year‑round if you have risk factors or little sunlight exposure.[25].
Spend time outdoors – During spring and summer, short periods of sunlight exposure (without sunscreen on small areas of skin) help your body produce vitamin D. Avoid sunburn by seeking shade during peak hours and using sunscreen after a few minutes[26].
Eat vitamin D‑rich foods – Include oily fish, egg yolks, liver, red meat and fortified foods in your diet[27].
Maintain a healthy weight – Obesity is linked to lower bioavailability of vitamin D[20].
Check medication interactions – Some drugs can reduce vitamin D levels[19].
Consult Medcare healthcare professional – Seek advice before starting high‑dose supplements, if you are pregnant or have underlying health conditions.

FAQs

Can low vitamin D cause hair loss or skin problems?

Research on vitamin D and hair loss is limited. Vitamin D plays a role in skin cell growth and hair follicle cycling, and severe deficiency may contribute to conditions like alopecia areata. However, evidence is inconclusive. Maintaining adequate vitamin D is beneficial for general health, but consult a dermatologist if you experience significant hair or skin issues.

Is vitamin D deficiency linked to anxiety and depression?

Some studies report associations between low vitamin D and mood disorders, including depression and anxiety. Vitamin D receptors in the brain may influence neurotransmitter function. Supplementation could improve mood in deficient individuals, but it is not a substitute for professional mental health care.

How long does it take to correct vitamin D deficiency?

Correction depends on the severity of deficiency, the dose prescribed and individual factors. A loading dose may raise levels within a few weeks. Maintenance supplementation (10 µg daily) helps keep levels stable. Follow your doctor’s recommendations and recheck levels as advised.

Can vitamin D deficiency occur even if I eat a balanced diet?

Yes. Diet alone rarely provides enough vitamin D; oily fish and fortified foods contribute, but most people need supplementation[28]. Sunlight exposure and supplements are key sources.

Are vitamin D3 and D2 supplements equally effective?

Vitamin D3 (cholecalciferol) is generally more effective at raising blood vitamin D levels than vitamin D2 (ergocalciferol)[29]. D2 is plant‑derived and suitable for vegetarians and vegans. Choose products providing 10 µg per dose unless advised otherwise.

Internal Links and Further Reading

To learn more about vitamin D and how to optimise your levels, explore these related articles:

Vitamin D Guide: Benefits, Deficiency & Supplements – Comprehensive overview of vitamin D.
Read more here: Vitamin D Guide

What is Vitamin D and Why It’s Essential – Basic explanation of the vitamin and its functions.
Learn more here: What is Vitamin D?

Vitamin D3 vs D2: Which Form Is Better? – Comparison of the two forms of vitamin D.
How Much Vitamin D Do You Need Daily? – Age‑specific dosage recommendations.
Best Sources of Vitamin D: Food, Sun & Supplements – Practical tips on obtaining vitamin D.
Who’s at Risk of Vitamin D Deficiency in the UK? – Detailed risk factors and prevention strategies.
FAQs About Vitamin D Supplements – Answers to common supplementation questions.

Recognising the symptoms and risks of vitamin D deficiency is the first step toward protecting your bones, muscles and overall health. If you suspect you’re deficient or belong to a high‑risk group, talk to your GP or pharmacist at MedCare Health Clinic about testing and appropriate supplementation.

References

[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [17] [19] Vitamin D Deficiency: Causes, Symptoms, and Treatment

https://patient.info/bones-joints-muscles/osteoporosis-leaflet/vitamin-d-deficiency

[11] [28] NDNS: results from years 9 to 11 (combined) – statistical summary – GOV.UK

https://www.gov.uk/government/statistics/ndns-results-from-years-9-to-11-2016-to-2017-and-2018-to-2019/ndns-results-from-years-9-to-11-combined-statistical-summary

[12] [13] [16] [18] [20] [21] [22] [23] Vitamin D deficiency in adults | Health topics A to Z | CKS | NICE

https://cks.nice.org.uk/topics/vitamin-d-deficiency-in-adults/

[14] [24] [27] Vitamin D – NHS

https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-d/

[15] [25] Vitamin D deficiency: migrant health guide – GOV.UK

https://www.gov.uk/guidance/vitamin-d-deficiency-migrant-health-guide

[26] [29] Vitamin D – BDA

https://www.bda.uk.com/resource/vitamin-d.html