Two young women in the United Kingdom who considered themselves healthy experienced sudden physical collapses, and subsequent blood tests revealed they both had severely low vitamin D levels, according to reporting by FIT FOR FUN. Whether the deficiency directly caused either collapse remains medically unconfirmed. The cases have drawn attention to a nutritional shortfall that doctors say frequently escapes notice, particularly among adolescents and young adults.
Saskia Reeves-Priestley, 23, played football four times a week, usually as a goalkeeper. She told the BBC, as reported by FIT FOR FUN, that she believed she was fit and well until she collapsed without warning at work. She felt dizzy and nauseous, her heart raced, and her body felt unusually hot. A blood test later showed her vitamin D level was close to zero by her own account. She now takes vitamin D supplements regularly and has returned to playing football.
The second case involved Amaka Osu, a 21-year-old student. She was cooking dinner in her Liverpool flat when she began shaking uncontrollably and her eyesight deteriorated to the point where she could barely see. A flatmate took her to an emergency department. Testing later showed her vitamin D was also too low. As with Reeves-Priestley, no definitive link was established between the deficiency and her acute symptoms.
Osu told the BBC she had been accustomed to feeling tired, but had put it down to the demands of her studies and job. "I'm a 21-year-old student. I have work and university — I'm always tired," she said, according to FIT FOR FUN. She has improved since starting supplements, but the episode still frightens her.
Why it matters
Vitamin D deficiency is often described by clinicians as a silent condition, and the two British cases illustrate why. Suma Uday, a paediatric endocrinologist in the UK, told the BBC that the symptoms are typically vague and easy to attribute to other causes, which means deficiencies in younger people can go undetected for a long time.
The scale of the problem among young people is significant. According to the UK's National Diet and Nutrition Survey, cited by FIT FOR FUN, nearly one in four adolescents aged 11 to 18 had a vitamin D deficiency in the most recent assessment. Girls and young women are particularly affected, and UK doctors report seeing low levels increasingly in certain age groups.
The issue is not confined to Britain. FIT FOR FUN notes that vitamin D deficiency is also relatively common among young people in Germany, based on survey data collected between 2008 and 2011. Because a shortage can persist for months without producing clear signals, those affected may simply feel worn down and dismiss it.
What the deficiency does to the body
Vitamin D helps the body absorb calcium from food and supply bones with the minerals they need. When levels stay low over an extended period, bone structure can suffer. In osteomalacia, bones become soft and break more easily. Uday warned that the disease can weaken bones gradually without early warning signs.
Sunlight is the main driver of vitamin D production, and in Germany the sun's rays are generally too weak between October and March for the skin to make enough of it. The skin requires UVB radiation, which is scarce in winter because the sun sits low in the sky. The body therefore draws on reserves built up during sunnier months.
Skin tone also plays a role. Under identical conditions, people with darker skin need more sunlight to produce comparable amounts of vitamin D. Clothing and sunscreen reduce production as well, though both remain important for preventing skin damage. Oily fish and other foods contribute some vitamin D, but diet alone often cannot meet the full requirement.
Screening thresholds and food fortification under debate
British doctors are currently discussing which blood values should define a deficiency. An expert group called ACT NOW Vitamin D, which includes Uday, is calling for higher thresholds, arguing that more at-risk people could then be identified in time. There is no complete medical consensus on the appropriate cut-off.
Martin Hewison, a professor at the University of Birmingham, raised a separate concern in comments to the BBC: roughly a century after vitamin D was discovered, rickets has not disappeared. He has called for consideration of stronger fortification of food with vitamin D. Canada and Sweden already have mandatory requirements, while in the UK many foods are fortified voluntarily.
FIT FOR FUN also points to a caveat for anyone considering supplements. Taking vitamin D does not automatically protect against fractures. An analysis of 69 studies covering nearly 154,000 adults found little preventive benefit for most older people examined. That finding does not necessarily apply to people with a confirmed deficiency or specific medical conditions.
For prevention, the German Federal Institute for Risk Assessment (BfR) recommends regular time outdoors, a balanced diet and, where needed, dietary supplements. FIT FOR FUN's report suggests these measures can help ward off a shortfall, though anyone with persistent fatigue or unexplained symptoms should seek medical advice rather than assume the cause.
Watch for further guidance from UK health bodies on deficiency thresholds and fortification policy, and for wider debate over whether mandatory vitamin D addition to foods should be adopted beyond Canada and Sweden.
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