Who Is at Highest Risk
- People with darker skin (need more sun exposure to make equivalent vitamin D)
- Older adults (skin makes less vitamin D with age)
- People who cover most of their skin for religious/cultural reasons
- Those with limited sun exposure (housebound, night shift workers)
- Obesity (vitamin D is sequestered in fat tissue)
- Malabsorption conditions (coeliac disease, IBD, post-bariatric surgery)
- People living in northern latitudes, especially in winter
Symptoms of Deficiency
| Severity | Symptoms |
|---|---|
| Mild-moderate | Often asymptomatic or vague fatigue, mild aches |
| More significant | Bone pain, muscle weakness, increased fall risk in elderly |
| Severe (rare in developed countries) | Osteomalacia (bone softening) in adults, rickets in children |
Treatment Regimen
| Severity | Treatment |
|---|---|
| Severe deficiency (<25 nmol/L) | High-dose loading: 50,000 IU weekly for 6-8 weeks, or equivalent daily dosing |
| Moderate deficiency (25-50 nmol/L) | 800-2000 IU daily for 3 months, then recheck |
| Maintenance (after correction) | 400-1000 IU daily, ongoing, especially in winter |
Everyone in Northern Latitudes Should Consider Winter SupplementationPublic health guidance (UK, Northern Europe, Canada, northern US) recommends everyone consider a 10mcg (400 IU) vitamin D supplement during autumn and winter months, when UVB sunlight isn't sufficient to make vitamin D.
Can I get enough vitamin D from food alone?
It's very difficult — few foods contain significant vitamin D (oily fish, fortified foods), which is why sunlight exposure (in summer) and supplementation (in winter or for at-risk groups) are the main sources for most people.
How long does it take to correct vitamin D deficiency?
With appropriate loading dose treatment, levels typically normalise within 6-12 weeks, though ongoing maintenance supplementation is usually needed to prevent recurrence.
Can too much vitamin D be harmful?
Yes, though this requires very high doses over prolonged periods — stick to recommended doses unless under medical supervision for treating diagnosed deficiency.
Medical Disclaimer: This page is for general education only and does not replace professional medical advice. Always consult a qualified healthcare provider.