What really happens if I’m not getting sufficient Vitamin D?

Half the adult population in Ireland and the UK have less than optimal levels of Vitamin D3.

Vitamin D3 (cholecalciferol)is the form of vitamin D produced in your skin when exposed to UVB sunlight and the primary form found in animal-based foods or supplements. It is one of two main forms of vitamin D (the other being D2, ergocalciferol, from plant sources)

We’ve put together a Vitamin D Deficiency ‘thermometer’, that maps out the risks and benefits of this vital Vitamin. If you’re interested in knowing more about any of the statements below, click the glowing asterisks, these will direct you to the scientific research to back it up.

References

  1. Vitamin D and prevention of breast cancer: pooled analysis – link
  2. COVID-19 Mortality Risk Correlates Inversely with Vitamin D3 Status, and a Mortality Rate Close to Zero Could Theoretically Be Achieved at 50 ng/mL 25(OH)D3: Results of a Systematic Review and Meta-Analysis – link
  3. Vitamin D and prevention of breast cancer: pooled analysis – link
  4. NHS overview of Osteoporosis – link
  5. Expression of the multiple sclerosis-associated MHC class II Allele HLA-DRB1*1501 is regulated by vitamin D – link
  6. 1,25-Dihydroxyvitamin D(3) is a negative endocrine regulator of the renin-angiotensin system – link
  7. Myocardial infarction is inversely associated with plasma 25-hydroxyvitamin D3 levels: a community-based study – link
  8. The prevalence of vitamin D inadequacy amongst women with osteoporosis: an international epidemiological investigation – link
  9. Vitamin D deficiency is associated with anxiety and depression in fibromyalgia – link
  10. Vitamin D and autoimmune disease – link
  11. Schizophrenia, vitamin D, and brain development – link
  12. Vitamin D and diabetes – link
  13. Vitamin D Deficiency Common in Patients With Chronic Migraine – link
  14. Maternal vitamin D deficiency increases the risk of preeclampsia –
    link
  15. Vitamin D for Cancer Prevention: Global Perspective – link
  16. NIH Vitamin D Factsheet – link

How Vitamin D3 Is Measured?

Vitamin D3 itself is not typically measured directly in routine tests. Instead, doctors measure25-hydroxyvitamin D [25(OH)D or calcidiol], the main circulating form in the blood.

Method: A simple blood test (serum or plasma) drawn from a vein or sometimes a finger prick. No fasting is usually required.

Button label

Why Is Vitamin D Important?

Bone Strength

It promotes calcium and phosphorus absorption in the intestines, enabling normal bone mineralization. Deficiency can cause rickets (in children), osteomalacia (soft bones in adults), and contribute to osteoporosis.

Muscle Function

Supports muscle strength and reduces fall risk, especially in older adults.

Immune System

Helps modulate immune responses and may reduce risk of respiratory infections.

Other Roles

Involved in reducing inflammation, cell growth, glucose metabolism, and neuromuscular function. Low levels are linked to higher risks of various conditions (cardiovascular, autoimmune, certain cancers, etc.), though causation is not always fully established

What next?

For personalised advice, get a Vitamin D3 blood test (link) and consult a doctor, dietitian or nutritional therapist - especially if you have symptoms or risk factors. Levels can be improved safely with supplementation, sun exposure and diet.

TEST YOUR LEVELS

Other Articles About Vitamin D

View all
1 3
View all