A 23-year-old special educational needs teacher experienced a sudden collapse at work that would expose a widespread health issue affecting thousands of young people across the UK. According to BBC News, Saskia Reeves-Priestley's unexpected medical emergency revealed she was severely vitamin D deficient, with blood tests showing levels that were "next to nothing" despite her appearing fit and healthy.
Reeves-Priestley, who played football four times weekly as a keen goalkeeper, described the moment her health deteriorated without warning. "I just felt really dizzy, really nauseous, was having heart palpitations and was really hot," she recalls. Her case highlights a growing concern among medical professionals: vitamin D deficiency is becoming increasingly common in young people, particularly girls and young women, yet remains difficult to diagnose because symptoms often go unrecognised.
How widespread is vitamin D deficiency among young people?
The problem is more prevalent than many realise. Data from the National Diet and Nutrition Survey showed that nearly a quarter of 11- to 18-year-olds in the UK were classified as deficient in the most recent year measured. Research conducted at a Birmingham children's emergency department in 2026 found even more concerning figures: 62 of 239 tested children and young people (25.9%) had vitamin D deficiency, while another 88 (36.8%) had insufficient levels. The study's authors emphasised that UK screening is not currently recommended and called for targeted diagnostic strategies for populations at greater risk.
What causes vitamin D deficiency?
The body produces most of its vitamin D when ultraviolet light from sunlight strikes the skin, though smaller amounts come from dietary sources such as oily fish and meat. Geographic location and season significantly affect production rates: lower levels of sunlight during winter months and in northern regions reduce the body's capacity to synthesise vitamin D. Protective measures such as covering skin and wearing sunscreen, while essential for preventing skin cancer, also decrease vitamin D production. People with darker skin tones require exposure to stronger light to produce equivalent amounts of vitamin D compared to those with lighter skin.
What are the symptoms and how do they affect daily life?
Vitamin D deficiency is often called "the silent disease" because its symptoms are subtle and easily overlooked. Dr Suma Uday, a paediatric endocrinologist, warns that the condition is difficult to identify and frequently missed or misdiagnosed. Symptoms include fatigue, joint pain, and bone pain. "It's basically silently eating away at the bones, leaving them softened and prone to breaks," Uday explains. In babies and infants, severe deficiency causes rickets; in adults, a similar bone-weakening condition called osteomalacia develops.
Amaka Osu, a 21-year-old university student in Liverpool, experienced the condition's sudden onset while preparing dinner at her student house. "I couldn't really see in front of me," she says, describing how she began shaking uncontrollably. Her housemate rushed her to accident and emergency, where she too received a diagnosis of vitamin D deficiency. Osu had attributed her tiredness to the demands of university and work, unaware that her symptoms indicated a serious deficiency. She remembers her mother having experienced low vitamin D but did not realise the condition could affect her. After beginning supplementation, Osu's symptoms improved significantly, though she remains anxious about recurrence. "It was scary and I don't want to experience that again," she says.
Why is diagnosis so difficult?
Currently, doctors do not routinely offer blood tests to check for vitamin D deficiency. They will recommend a supplement only if a patient expresses concern about being at high risk. This reactive approach means many cases go undetected until symptoms become severe enough to prompt medical attention. Uday and other clinicians have formed a group called ACT NOW Vitamin D, which is calling for the threshold at which people are classified as deficient to be raised. Raising this threshold would identify more individuals with low vitamin D and provide a more accurate picture of how widespread the issue truly is, allowing earlier treatment intervention.
What are the long-term consequences?
The implications extend far beyond individual cases. Uday warns of "a lifelong deficit" that can affect women across multiple life stages—during adolescence, pregnancy, and affecting newborns. "If you don't correct it from the very beginning," she says, "this is going to affect multiple generations." Prof Martin Hewison from the University of Birmingham emphasises the seriousness of the situation: despite vitamin D being discovered 100 years ago, "rickets hasn't gone away." He notes that the presence of rickets in communities indicates many more people are vitamin D deficient than official figures suggest.
What solutions are experts proposing?
Hewison advocates for wider food fortification, where vitamins are added to foods during production. Countries including Canada and Sweden have implemented mandatory fortification policies. In the UK, some foods such as breakfast cereals and spreads are already fortified with vitamin D, but fortification remains voluntary rather than mandatory. "We might have to accept that for certain groups vitamin D supplementation is a matter of course," Hewison suggests.
Current guidance from NICE recommends that people consider a daily 10-microgram (400 IU) supplement during autumn and winter months, while people with darker skin or those with little sun exposure are advised to take supplements year-round. On 20 October 2026, NICE updated its vitamin D supplement guidance, retaining recommendations to improve supplement access for groups at risk and to test only when symptoms, particularly high risk, or a clinical reason warrant it.
Saskia Reeves-Priestley now takes vitamin D supplements regularly and has returned to playing goalkeeper. Her experience, along with cases like Amaka's, underscores the importance of awareness among young people and healthcare providers about this often-overlooked condition that can strike even the apparently healthiest individuals.
