Celiac disease most often leaves people short on iron, calcium, vitamin D, folate, and vitamin B12, though zinc and magnesium commonly run low too.
The small intestine loses its ability to pull nutrients from food long before anyone names the disease, and iron, calcium, vitamin D, folate, and vitamin B12 are usually the first to slide. The list of what vitamins celiacs are deficient in keeps growing past those five, as well — zinc, magnesium, copper, and several B vitamins show up often enough that clinics test for them by default rather than waiting for symptoms to appear.
Which Nutrient Gaps Show Up Most Often?
Iron, calcium, vitamin D, folate, and vitamin B12 sit on nearly every official list, with zinc and magnesium close behind. Each gap traces back to one cause: the stretch of gut that absorbs the nutrient is the stretch celiac disease damages first.
- Iron. Low iron is one of the most frequent findings in undiagnosed celiac disease, and iron-deficiency anemia is sometimes the first clue that sends someone to a doctor.
- Calcium and vitamin D. Both support bone strength, and calcium is absorbed in the duodenum — the section of small intestine hit earliest.
- Folate and vitamin B12.
- Zinc.
- Magnesium, copper, niacin, riboflavin, and vitamin B6. The Celiac Disease Foundation lists these as likely gaps, though they turn up less consistently than the five above.
The table below pairs each nutrient with how frequently it shows up at diagnosis and what it does in the body.
| Nutrient | Gap At Diagnosis | Role In The Body |
|---|---|---|
| Iron | Common; frequently the first clue | Oxygen transport; fatigue and anemia |
| Zinc | 59.4% of adults in one review | Immunity, wound healing, taste |
| Vitamin B12 | Insufficiency up to 41% | Red blood cells and nerves |
| Folate (B9) | 18%–90% across studies | Cell division, red blood cells |
| Vitamin D | Frequent; tied to bone loss | Helps the body absorb calcium |
| Calcium | Common in untreated disease | Bone density and nerve signals |
| Magnesium | Frequently low and missed | Energy, muscle, blood pressure |
| Copper | Low at diagnosis in studies | Iron use, connective tissue |
Why Does Celiac Disease Drain These Nutrients?
Celiac disease flattens the villi — the finger-like folds that line the small intestine and absorb nutrients — so food keeps moving through while the nutrients inside it never get taken in. Iron, calcium, and folate are absorbed high up in the duodenum, which is why those three drop first and hardest.
Untreated and newly diagnosed disease is the riskiest window. Gluten is the trigger, so a strict gluten-free diet is the main treatment: it lets the intestine heal and absorption improve over time. Celiac Disease Foundation’s treatment and follow-up guidance notes that some people still need supplements covering vitamin B12, folate, iron, vitamin D, copper, zinc, or vitamin K after they go gluten-free.
Vitamin Deficiencies In Celiac Disease: What Testing Finds
Mayo Clinic says nutritional testing after a diagnosis may cover vitamins A, B-12, D, and E plus mineral levels, hemoglobin, and liver enzymes. The Celiac Disease Foundation’s adult checklist adds a complete blood count, iron studies, thyroid function, liver enzymes, calcium, phosphate, 25-hydroxy vitamin D, copper, and zinc. Newly diagnosed patients in particular should be checked for iron, folic acid, vitamin B12, and vitamin D.
Two mistakes cost people time. The first is assuming every celiac patient runs low on the same nutrients — the pattern shifts with age, how severe the disease was, how long it went untreated, and how closely the gluten-free diet is followed. The second is treating that diet as automatically complete. Planned poorly, it can fall short on fiber, B vitamins, iron, calcium, and magnesium, which is where a targeted supplement earns its place — our tested multivitamin picks for celiac disease break down which formulas list usable forms. Get levels checked before adding anything, then recheck once the gut has had time to heal.
FAQs
Do nutrient levels recover on a gluten-free diet?
Yes, absorption usually improves once the intestine heals, and that healing takes time rather than happening overnight. Many people still need supplements in the meantime, because the gut has to recover before it can pull nutrients from food efficiently. Repeat bloodwork is what shows whether levels are actually climbing.
Is iron deficiency always a sign of celiac disease?
No. Iron deficiency has many causes, from heavy periods to low dietary intake, and most people who have it do not have celiac disease. Even so, unexplained iron-deficiency anemia is a recognized reason doctors test for celiac disease, especially when no obvious source turns up.
Can a gluten-free diet create its own nutrient gaps?
Yes. Gluten-free flour blends and packaged products are frequently lower in fiber, iron, calcium, magnesium, and some B vitamins than wheat-based versions. Diet quality decides the outcome, which is why the Celiac Disease Foundation recommends routine monitoring instead of assuming the diet covers everything.
References & Sources
- Celiac Disease Foundation. “Treatment and Follow-Up.” Covers the nutrients most frequently low in celiac disease and the tests used to track them.
- Mayo Clinic News Network. “Study Finds Micronutrient Deficiencies Common at Time of Celiac Disease Diagnosis.” Source for the 59.4% zinc finding and the post-diagnosis testing panel.
What vitamins are celiacs deficient in? See the nutrient gaps Mayo Clinic and the Celiac Disease Foundation flag most, plus the tests that catch them.