Autoimmune diseases are frequently associated with low vitamin D levels. But does supplementing with vitamin D actually help manage or improve these conditions?
While vitamin D is essential for immune regulation, supplementation alone doesn’t always deliver the expected results. In this article, we explore why vitamin D is important, the research behind it, and what to consider when using it as part of a natural autoimmune protocol.
What Are Autoimmune Diseases?
Autoimmune diseases occur when the immune system mistakenly attacks the body’s own tissues. This can lead to chronic inflammation and damage to organs such as the thyroid, gut, skin, joints, or nervous system.
Examples include:
- Hashimoto’s thyroiditis
- Rheumatoid arthritis
- Multiple sclerosis (MS)
- Psoriasis
- Crohn’s disease
- Lupus
There is currently no known medical cure, but many people experience improvement through lifestyle interventions and holistic therapies. One of the key nutrients considered in these approaches is vitamin D.
Why Vitamin D Matters in Autoimmune Conditions
Vitamin D is not just important for bone health. It plays a pivotal role in regulating immune system function (1).
Scientific research shows that vitamin D receptors are present in many immune cells—including T cells, dendritic cells, and monocytes—indicating its central role in immune system balance. Its anti-inflammatory effect has been widely recognized, especially in autoimmune conditions where inflammation is a driving factor (2).
Key takeaway: Low vitamin D levels may contribute to the loss of immune tolerance—the ability to distinguish between self and non-self—which can trigger or worsen autoimmune disease.
A 2013 review concluded that vitamin D deficiency may impair self-tolerance in genetically predisposed individuals, potentially contributing to autoimmune disease development (3).
Does Vitamin D Reduce the Risk of Autoimmune Diseases?
Yes—emerging research supports this. A landmark 2022 study published in the British Medical Journal (BMJ) followed over 25,000 participants and found that:
- Daily supplementation of 2,000 IU of vitamin D reduced the risk of autoimmune diseases by 22% over five years.
- Those taking vitamin D were less likely to develop diseases such as rheumatoid arthritis, psoriasis, or thyroid autoimmunity compared to the placebo group.
This is one of the most robust clinical trials supporting the preventive role of vitamin D in autoimmunity (4).
Why Vitamin D Sometimes Doesn’t Work
Despite its importance, many people with autoimmune diseases see no benefit from conventional vitamin D supplementation. Why?
Earlier studies used low doses that had minimal effects. More recent research tested higher intermittent doses (e.g., 100,000 IU every 2 weeks), but even those results were inconsistent.
A growing body of evidence points to a possible explanation: vitamin D resistance.
What Is Vitamin D Resistance?
Vitamin D resistance means the body does not respond effectively to vitamin D, even when blood levels appear adequate. This may be due to:
- A blockage of the vitamin D receptor (VDR) pathway
- Chronic infections or inflammation affecting cellular response
- Genetic variations or acquired resistance over time
When this resistance is present, typical vitamin D supplementation may have little to no impact on symptoms.
Prof. Dr. Jörg Spitz and other researchers have proposed vitamin D resistance as a contributor to autoimmune diseases and advocate for a therapeutic approach involving higher doses (5).
High-Dose Vitamin D Therapy: The Coimbra Protocol
One of the most researched approaches to overcoming vitamin D resistance is the Coimbra Protocol, developed by Brazilian neurologist Dr. Cicero G. Coimbra. It involves personalised high-dose vitamin D therapy for patients with autoimmune conditions.
Coimbra Protocol Dosage Overview (Initial Guidance Only):
Always work with a trained healthcare provider for proper dosing and monitoring.
| Autoimmune Condition | Starting Dose (IU per kg body weight) |
| Multiple sclerosis | 1,000 IU/kg |
| Rheumatoid arthritis, lupus, Crohn’s disease, psoriasis, Ulcerative Colitis | 300–500 IU/kg |
| Hashimoto’s, scleroderma, ankylosing spondylitis | 300 IU/kg |
| Other autoimmune diseases | 150 IU/kg |
This approach aims to overcome vitamin D resistance by ensuring high enough receptor activation to initiate gene expression and immune modulation.
Safety Considerations with High-Dose Vitamin D
The High-dose therapy must be carefully supervised to prevent hypercalcemia—a condition where too much calcium accumulates in the blood.
Safety measures include:
- Regular blood and urine calcium monitoring
- Low-calcium diet during therapy
- Monitoring for symptoms like frequent urination, excessive thirst, constipation, or fatigue
Warnings found online about the Coimbra Protocol usually stem from isolated cases where safety protocols weren’t followed. When supervised appropriately, many patients report significant improvements.
Should You Take Vitamin D for Autoimmune Disease?
If you have an autoimmune condition or are at high risk of developing one, consider:
- Testing your vitamin D levels through blood work
- Discussing appropriate dosing with your GP, integrative doctor, or Coimbra-trained practitioner
- Exploring the root causes of vitamin D resistance if conventional supplementation hasn’t worked
Vitamin D alone is not a cure—but in the right form, dose, and context, it can be a valuable tool in a broader natural treatment plan.
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