When we think of Vitamin D, most of us associate it with bone health. While this is true, Vitamin D is a powerful hormone with roles far beyond keeping our skeleton strong. It influences mood, immunity, energy, and even reproductive health. In this blog, we’ll explore the difference between how conventional medicine and naturopathy view Vitamin D testing, its implications for health, and why functional ranges matter.
Why Test for Vitamin D?
In Australia, doctors are guided by strict Medicare criteria when testing Vitamin D. Testing is typically ordered only when clinical risks or conditions suggest deficiency.
When Doctors Test Vitamin DDoctors look for Vitamin D deficiency to manage or prevent serious health concerns, such as:
Bone Health: Suspected osteoporosis or rickets (in children).
Gastrointestinal Disorders: Conditions like coeliac disease or other causes of malabsorption.
Renal Health: Chronic kidney disease (CKD) or renal failure.
Parathyroid and Calcium Disorders: Hyperparathyroidism, hypocalcaemia, or hypophosphataemia.
Sunlight Deficiency: Limited sun exposure or darker skin tones, which reduce Vitamin D synthesis.
For doctors, a Vitamin D level below 50 nmol/L is the marker for deficiency. This threshold ensures timely intervention to prevent conditions like fractures, hypocalcaemia, or other serious outcomes.
The Functional Medicine Approach
While conventional medicine focuses on treating deficiency, naturopathy takes a broader perspective. Naturopaths and functional medicine practitioners assess Vitamin D to optimise health and prevent chronic disease long before symptoms appear.
What Do Naturopaths Look For? Naturopaths aim for a functional range of 75–125 nmol/L—levels supported by research to promote whole-body wellness.
This optimal range has been linked to:
Bone Health and Fracture Prevention: Research demonstrates that Vitamin D, combined with calcium, significantly reduces fracture risk in older adults. A meta-analysis confirmed its effectiveness in improving bone mineral density and reducing falls associated with osteoporosis (Bischoff-Ferrari et al., 2005).
Immune Function and Autoimmunity Vitamin D deficiency has been associated with autoimmune diseases like multiple sclerosis and rheumatoid arthritis. Studies suggest Vitamin D reduces inflammatory cytokines while enhancing anti-inflammatory pathways, supporting immune balance (Aranow, 2011).
Mental Health and Depression A meta-analysis found that Vitamin D supplementation improved symptoms of depression, particularly Seasonal Affective Disorder, by modulating serotonin pathways (Spedding, 2014).
Cardiovascular Health Evidence links low Vitamin D levels to hypertension and cardiovascular disease. Supplementation has been shown to improve vascular health and lower blood pressure (Pilz et al., 2016).
Respiratory and Infectious Disease Clinical trials during the COVID-19 pandemic highlighted Vitamin D's protective role in respiratory infections, showing reduced severity and frequency of acute respiratory illnesses (Martineau et al., 2017).
By identifying suboptimal levels—even when they don’t meet the threshold for clinical deficiency—naturopaths can uncover imbalances contributing to fatigue, poor immunity, or mood disorders.
The Science of Functional Ranges
The difference between conventional and functional ranges comes down to their purpose. Conventional medicine defines "normal" ranges based on averages from the population, which often includes people already unwell. Functional ranges, however, focus on optimal health—levels where the body thrives, not just survives.
For example, while a Vitamin D level of 55 nmol/L may not raise red flags in a conventional setting, research suggests this may be insufficient to support immune function, mental health, and chronic disease prevention. A functional practitioner would address this "suboptimal" level to optimise your overall well-being.
Vitamin D: Part of the Bigger Picture
Vitamin D is just one marker in your health journey. Functional practitioners look at it alongside other blood tests, symptoms, and your unique health history to create a tailored treatment plan.
Low Vitamin D + Fatigue: This could point to hormone imbalances or nutrient deficiencies.
Low Vitamin D + Inflammation: May highlight immune dysfunction or chronic stress.
Low Vitamin D + Fertility Concerns: Can signal the need for broader hormonal support.
This comprehensive approach ensures we’re addressing root causes, not just symptoms.
Optimise Your Vitamin D Today
Are you curious about your Vitamin D levels? Whether you're struggling with low energy, mood swings, or simply want to feel your best, testing your levels can provide valuable insight.
Speak with a naturopath to explore your unique health picture and what steps you can take to optimise it. Book a Free Discovery Call with us!
References
RACGP Clinical Guidelines: Vitamin D Testing. Link
Holick, M. F. (2007). Vitamin D deficiency. New England Journal of Medicine, 357(3), 266–281.
Pludowski, P., et al. (2013). Vitamin D effects on musculoskeletal health, immunity, autoimmunity, cardiovascular disease, cancer, fertility, pregnancy, dementia, and mortality—a review of recent evidence. Autoimmunity Reviews, 12(10), 976–989.
Vieth, R. (1999). Vitamin D supplementation, 25-hydroxyvitamin D concentrations, and safety. American Journal of Clinical Nutrition, 69(5), 842–856.
Bischoff-Ferrari, H. A., et al. (2005). Effect of Vitamin D on falls: A meta-analysis. JAMA.
Aranow, C. (2011). Vitamin D and the immune system. J Investig Med.
Spedding, S. (2014). Vitamin D and depression: A systematic review and meta-analysis. Br J Psychiatry.
Pilz, S., et al. (2016). Vitamin D and cardiovascular disease prevention. Nat Rev Cardiol.
Martineau, A. R., et al. (2017). Vitamin D supplementation to prevent acute respiratory infections: A systematic review and meta-analysis. BMJ.
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