The Hidden Role of Vitamin D in Celiac Disease and Other Chronic Inflammatory Conditions

Celiac.com 09/29/2025 - Vitamin D has long been associated with healthy bones and the regulation of calcium in the body. However, scientists now understand that its role extends far beyond skeletal health. Almost every cell in the body has receptors for vitamin D, meaning it can influence hundreds of processes. Vitamin D is created in the skin when exposed to sunlight and can also be consumed in foods or supplements. After being processed in the liver and kidneys, it becomes active and influences cell growth, immunity, and the integrity of tissue barriers such as skin and gut linings.

Deficiency in vitamin D has been linked to autoimmune diseases, heart disease, metabolic syndrome, inflammatory bowel disease, and celiac disease. Researchers are increasingly focusing on how vitamin D may help prevent or manage these chronic conditions by strengthening epithelial barriers and regulating immune responses.

Vitamin D and Skin Health

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The skin is both a producer and a target of vitamin D. Active vitamin D helps skin cells mature properly, strengthens the outermost protective layer, and regulates proteins that keep skin cells tightly connected. These actions prevent harmful microbes and allergens from entering the body. In conditions such as atopic dermatitis (eczema) and psoriasis, the skin barrier becomes weakened. Low vitamin D levels are common in people with these conditions, and deficiency may worsen symptoms.

Research shows that vitamin D reduces inflammation by calming overactive immune cells and increasing antimicrobial peptides that protect against bacteria. Clinical studies indicate that supplementation can lessen the severity of eczema and psoriasis, especially when combined with standard treatments. Topical vitamin D creams are also widely used for psoriasis, where they help restore normal skin growth and reduce redness and scaling.

Vitamin D and Cardiovascular Health

Beyond its skin benefits, vitamin D is also active in the heart and blood vessels. Cells lining blood vessels have vitamin D receptors, which allow the vitamin to regulate blood pressure, prevent excess inflammation, and improve vessel flexibility. Deficiency has been associated with high blood pressure, heart attacks, and strokes.

Studies in both animals and humans show that vitamin D can lower blood pressure by reducing overactivity in a hormone system that controls fluid balance. It may also improve cholesterol levels, support insulin function, and reduce oxidative stress. However, large trials on vitamin D supplementation have shown mixed results. Some groups, such as the elderly or those with severe deficiency, appear to benefit more, while others show little change. This suggests that vitamin D may be most important in correcting deficiencies rather than providing extra benefit in already healthy people.

Vitamin D and the Gut Barrier

The intestines serve as one of the body’s most important protective barriers. They allow nutrients to pass through while keeping harmful microbes and toxins out. This barrier relies on specialized proteins that seal cells together and immune cells that respond appropriately to threats. When this system fails, the result is often inflammation and chronic disease.

Vitamin D helps maintain this balance by supporting tight junction proteins, preventing excessive cell death, and encouraging healthy regeneration. It also shapes the immune response in the gut, encouraging tolerance instead of constant inflammation. Importantly, vitamin D affects the composition of gut bacteria, helping maintain a diverse and balanced microbiome. Studies in animals have shown that supplementing with vitamin D can repair damaged intestinal barriers, reduce harmful immune activity, and restore healthy gut structure.

Vitamin D in Inflammatory Bowel Disease and Celiac Disease

Inflammatory bowel diseases such as Crohn’s disease and ulcerative colitis, as well as celiac disease, all involve damage to the intestinal lining. This damage allows antigens and microbes to enter the body, fueling inflammation. Research shows that people with these conditions frequently have low vitamin D levels, and that deficiency is linked with more severe disease and higher relapse rates.

Animal experiments demonstrate that vitamin D supplementation can prevent gluten-induced damage in celiac-like conditions by restoring the tightness of intestinal barriers and reducing immune cell infiltration. In humans, people with celiac disease often improve their vitamin D levels once they start a gluten-free diet, which suggests that healing the gut improves absorption. Supplementation can further support bone strength and well-being in these patients. For inflammatory bowel disease, vitamin D supplementation has been shown to reduce inflammatory markers and lower relapse risk, though results vary depending on baseline levels and dosage.

Why This Matters for People with Celiac Disease

For people with celiac disease, the key to managing symptoms is strict avoidance of gluten. However, even with a gluten-free diet, many continue to face challenges such as weakened bones, persistent fatigue, and ongoing gut inflammation. Vitamin D may offer an additional layer of support by helping to restore barrier function in the intestine, calming inflammation, and strengthening the immune system.

Maintaining healthy vitamin D levels could reduce complications, improve quality of life, and possibly make the gut more resilient to accidental gluten exposure. While more studies are needed, the existing evidence suggests that vitamin D should be considered an important part of comprehensive care in celiac disease, alongside diet and other medical strategies.

Conclusion

Vitamin D is far more than a bone-strengthening nutrient. It is a powerful regulator of the skin, cardiovascular system, and intestinal barrier. By supporting epithelial integrity, balancing immune responses, and working with the microbiome, vitamin D helps the body resist chronic inflammation and disease. For those with conditions such as eczema, psoriasis, heart disease, inflammatory bowel disease, and especially celiac disease, ensuring adequate vitamin D intake may be an important step toward better health and long-term management.

Read more: preprints.org