What Nutrients Do Celiacs Lack and Why?

December 3, 2025 •

4 min read

According to the Celiac Disease Foundation, untreated celiac disease can commonly lead to deficiencies in nutrients such as fiber, iron, calcium, and several B vitamins. These deficiencies arise primarily from damage to the small intestine's lining, which impairs nutrient absorption, and can sometimes persist even after adopting a gluten-free diet.

Quick Summary

Celiac disease and its resulting intestinal damage commonly cause deficiencies in iron, calcium, vitamin D, and B vitamins due to poor absorption. Following a gluten-free diet often helps but may not fully resolve these issues, sometimes requiring supplementation and ongoing monitoring.

Key Points

Intestinal Damage Impairs Absorption: In celiac disease, gluten exposure damages the small intestine's villi, severely reducing its ability to absorb nutrients like iron, calcium, and vitamins.
Iron-Deficiency Anemia is Common: One of the most frequent extra-intestinal signs of celiac disease is iron-deficiency anemia, which often does not improve with oral iron supplements until a strict gluten-free diet is adopted.
Bone Health is at Risk: Malabsorption of calcium and vitamin D can weaken bones, increasing the likelihood of osteoporosis and fractures, especially when diagnosis is delayed.
B Vitamin Deficiencies Can Persist: Even with a strict GFD, some patients may continue to experience deficiencies in B vitamins like folate and B12, possibly due to a lack of fortification in gluten-free foods.
The GFD Itself Presents Challenges: Many gluten-free products lack the fortification of their conventional counterparts and can be low in fiber and other micronutrients, requiring careful dietary planning.
Proactive Monitoring and Supplementation are Key: Regular monitoring of nutrient levels through blood tests, combined with a nutrient-rich diet and targeted supplementation, is vital for long-term health management.

Celiac Disease and Impaired Nutrient Absorption

Celiac disease is an autoimmune disorder where the ingestion of gluten leads to damage in the small intestine. This damage, known as villous atrophy, flattens the finger-like projections (villi) that line the intestine, significantly reducing the surface area available for nutrient absorption. The proximal small intestine, where key nutrients like iron and folate are primarily absorbed, is often most affected, though the entire small bowel can be involved. This compromised absorption is the root cause of many nutritional deficiencies seen in celiac patients, especially before diagnosis or if a strict gluten-free diet (GFD) is not followed.

The Most Common Deficiencies

Patients with celiac disease are particularly susceptible to deficiencies in several key micronutrients. The most frequently cited include:

Iron: Iron deficiency anemia is the most common extra-intestinal manifestation of celiac disease, sometimes presenting as the only symptom. Iron is crucial for producing hemoglobin, which carries oxygen throughout the body. Low iron levels can cause fatigue, weakness, and pale skin.
Calcium and Vitamin D: Both are essential for bone health, and their malabsorption can lead to reduced bone mineral density, increasing the risk of osteoporosis and fractures. Vitamin D is also critical for immune function. Secondary lactose intolerance, which can occur with celiac disease, further complicates calcium intake.
Folate (Vitamin B9): This B vitamin is necessary for cell growth and red blood cell formation. Folate deficiency can lead to megaloblastic anemia and is common in untreated celiac disease.
Vitamin B12: Absorbed in the lower small intestine, B12 deficiency is more common in severe or long-standing celiac cases. It can contribute to anemia and neurological issues.
Zinc: An essential trace element for immune function, wound healing, and growth, zinc deficiency is frequent in newly diagnosed celiacs. Some studies show that zinc levels can normalize with a strict GFD, while others suggest supplementation may be necessary.
Magnesium: Involved in over 300 biochemical reactions, magnesium deficiency can be a problem in celiac patients due to both malabsorption and lower levels in many gluten-free products compared to their gluten-containing counterparts.

The Dual Challenge: Malabsorption and the Gluten-Free Diet

For many patients, beginning a strict GFD allows the small intestine to heal, leading to improved nutrient absorption and a resolution of deficiencies. However, some nutritional challenges may persist. The quality of the GFD itself plays a significant role. Many commercially available gluten-free products are not fortified with the vitamins and minerals (like iron and folic acid) that are standard in their gluten-containing alternatives. Patients may also reduce their intake of fortified cereals or dairy due to misconceptions about gluten or temporary lactose intolerance. This makes balanced dietary choices crucial, emphasizing naturally gluten-free foods rich in nutrients.

Supplements and Monitoring

Working with a doctor and dietitian is key to managing these deficiencies. Blood tests can help identify specific nutrient gaps, guiding a targeted supplementation plan. A gluten-free multivitamin/mineral supplement is often recommended. However, some deficiencies, like those of calcium, vitamin D, and iron, may require higher doses than a standard multivitamin can provide. Regular follow-ups are important to monitor progress and adjust treatment as the intestinal lining heals and dietary habits evolve.

Nutritional Considerations in Celiac Disease: Untreated vs. Treated


Feature	Untreated Celiac Disease	Celiac Disease on a Strict GFD
Intestinal Villi	Severely damaged or flattened, leading to significantly reduced absorptive surface area.	Begin to heal and regenerate, restoring the ability to absorb nutrients over time (months to years).
Primary Cause of Deficiencies	Malabsorption due to intestinal damage is the main factor.	Dietary inadequacies due to the removal of fortified gluten-containing products can be a major issue, alongside potentially incomplete intestinal healing.
Iron Deficiency	Extremely common, often manifesting as anemia that is unresponsive to oral iron therapy.	Improves as the gut heals, but some individuals may require ongoing supplementation and monitoring, particularly women.
Vitamin B Deficiencies (Folate, B12)	Common, contributing to anemia and neurological symptoms.	Often improve, but deficiencies of folate and B12 can persist in some patients even with good GFD adherence.
Calcium & Vitamin D	Malabsorption is common, leading to low bone mineral density and increased fracture risk.	Absorption improves, but intake may still be insufficient due to diet or associated lactose intolerance. Supplementation is frequently recommended.
Zinc & Magnesium	Deficiencies are common due to malabsorption.	May improve with a balanced GFD, but can persist due to lower mineral content in some gluten-free products.

Conclusion: Prioritizing Nutrition Beyond Gluten Avoidance

While adopting a strict gluten-free diet is the foundational treatment for celiac disease, it is only the first step toward achieving full nutritional recovery. Celiac patients must actively monitor for and address potential nutrient deficiencies resulting from intestinal damage and dietary shifts. By understanding the common deficiencies in nutrients like iron, calcium, vitamin D, and B vitamins, and working closely with healthcare professionals, patients can create a comprehensive nutritional plan. This plan should prioritize naturally nutrient-dense, gluten-free foods and, when necessary, include carefully selected supplements to ensure long-term health and well-being. Ultimately, a proactive approach to nutrition is essential for overcoming the long-term health challenges associated with celiac disease.

For more information on living with celiac disease, including dietary tips and resources, the Celiac Disease Foundation is an excellent resource.

Frequently Asked Questions

The primary cause is malabsorption due to damage to the small intestine's lining (villous atrophy) caused by consuming gluten. This damage reduces the surface area available for absorbing nutrients from food.

Anemia is common in celiac patients due to malabsorption of iron, folate, and vitamin B12, all of which are crucial for red blood cell production. Iron-deficiency anemia is particularly prevalent.

Celiac disease impairs the absorption of calcium and vitamin D, both vital for strong bones. This can lead to low bone mineral density and an increased risk of osteoporosis over time, especially if the disease is undiagnosed.

While the GFD allows the gut to heal, many gluten-free alternatives are not fortified with the same vitamins and minerals (like B vitamins and iron) as their gluten-containing counterparts. This can lead to continued dietary inadequacies if not managed carefully.

Not all, but many do, especially in the initial phase of diagnosis or if a blood test reveals specific deficiencies. Your doctor or dietitian may recommend a gluten-free multivitamin or targeted supplements for iron, calcium, or Vitamin D.

If deficiencies persist, it could indicate poor adherence to the GFD, accidental gluten exposure, or another underlying condition. Further investigation and dietary assessment by a healthcare provider are necessary.

Naturally gluten-free foods rich in these nutrients include leafy green vegetables, legumes, nuts, fish, eggs, and fortified dairy or dairy alternatives.