Celiac Disease can result in impaired nutrient absorption leading to deficiencies, regardless of the duration and compliance of the gluten-free diet.
What is Celiac Disease?
Celiac disease is an autoimmune condition in which the immune system sends out a signal when gluten is consumed. This signal causes a cascade of inflammatory cytokines and antibodies to be released that end up causing harm to your own gut lining and result in the microvilli that line the intestinal wall from being damaged. This brush border made up of tiny hair-like structures called microvilli are what help your body digestive enzymes in order to help break down food and absorb nutrients.
Every time you consume gluten, the autoimmune attack causes more damage to your intestinal wall. The tight junctions that keep cells tightly packed together begin to develop gaps where food particles, pathogens and bacteria that don’t belong to leak through these gaps into the bloodstream. You can read more about this process here.
Celiac Disease requires a life-long strict avoidance of gluten in order to stop these autoimmune attacks. Of course this isn’t easy since gluten is an additive and is naturally a part of many foods such as bread, pasta, cookies and many other items. It requires a diet overhaul that can be very overwhelming. This is one of the first areas of transitioning to a gluten-free diet where the diet choices can lead to a lack of the nutrients needed to be healthy. However avoiding gluten remains the MOST important part of healing your gut and living a healthy life. It is non-negotiable.
What the research says
Healing the gut is the first step when you are diagnosed with Celiac disease. This can take up to 5 years. It requires dedication, effort and know-how. I coach people with Celiac to help them not only with the transitioning such as shopping, cooking, baking, navigating events, vacations, social life, but also the nutritional and health aspect of celiac disease. Making good food choices that still provide the nutrients you need.
For some with Celiac, they can continue to experience impaired nutrient absorption leading to deficiencies and thus serious health problems, regardless of the duration and compliance of the gluten-free diet.
There are many contributing factors to this such as:
- reduced gastric acid production
- small intestinal bacterial overgrowth
- autoimmune gastritis
- lack of intrinsic factor
- gluten cross contamination
- poor diet choices and insufficient intake of foods
- medication use
- excess alcohol
- smoking
- microvilli that never return to full height
- imbalance in the gut microbiota
- genetic variants
One research article said “ The restoration of the gut through strict adherence to a gluten-free diet does not always fully resolve deficiencies. A micronutrient deficiency in long-term Gluten-free patients was found in up to 20% of subjects for folic acid and 30% for vitamin B12. For this reason, regular monitoring of these nutrients is necessary during a gluten-free diet and supplementation should be provided as needed”.
My experience
In Mid January of 2026, I developed a mild tummy bug and within a week started feeling really awful. I had intense head pressure and what I can only describe as my brain vibrating inside my head, constantly 24/7. It continued without let up every single day for the next 12 weeks. While this was not painful, it was very concerning and distracting.
A Functional B12 deficiency
During the first 4 weeks I became depressed, mood swings, cried a lot, and was snapping at everyone. I also was not able to think straight, the brain fog was so intense, I had to stop working and seeing clients. I couldn’t formulate sentences and forgot words as I was talking. I was also extremely tired and was going to bed at 7pm and sleeping through to the next morning. I was also having to have naps in the day. I couldn’t exercise, I just had no energy. Doing simple tasks like hanging up the washing or making my bed left me breathless and panting.
Then my eyes started bouncing around ((Nystagmus) whenever I read on my phone or computer. They would dart around and I couldn’t read! I knew something was drastically wrong.So I asked my doctor for blood tests that I needed anyway.
- Serum B12 and MMA
- Homocysteine
- RBC folate and serum folate
- Complete blood count with ESR and platelets
- ferritin
Sure enough, I had iron deficiency and a functional B12 deficiency
The most important thing to note is that you can develop serious nerve symptoms ranging from neuropathy to neurological from a functional B12 deficiency even before anemia develops. These include dizziness, nerve pain, optic changes, pins and needles, cold sores, sore tongue, tics, joint and muscle pain, depression, anxiety, mood changes, paranoia, delusions, disassociation, aversion to social contact, GI issues, brain fog, confusion, balance problems and much more. B12 is connected to just about everything in your body and a deficiency can mimic some conditions like POTS, MCAS, ADHD, autonomic dysregulation and Fibromyalgia.
Iron Deficiency
I also had a iron deficiency. Having both an iron and B12 deficiency can be missed on labs. What happens is that iron deficiency causes small red blood cells called microcytic cells and B12 deficiency causes large red blood cells called macrocytic cells. Together these cancel each other out on a complete blood test making hemoglobin appear normal because it takes an average reading of red blood cells and with a mix of large and small, it appears to be fine. Doctors often miss this. Iron deficiency without anemia also causes symptoms ranging from feeling cold, dizzy, fatigue, shortness of breath, headaches, brain fog, hair loss, poor focus, low motivation, heart palpitations, weak and brittle nails.
MMA, RBC Folate and homocysteine
This is why other tests can be useful. MMA is not a cheap test, but it is important when you are investigating a deficiency and you are not sure if it is iron, B12 or folate. All three are involved in red blood cell production and can cause different types of anemias. MMA (methylmalonic acid) measures your cellular level of B12, how much of that circulating B12 has made it from the bloodstream into the cells over the past 4 months. It is a better indication of true B12 level. A high reading over 250 pmol/L indicates B12 deficiency.
Homocysteine is an amino acid that rises in a B12 or folate deficiency (it can rise for other reasons too).
RBC folate is the cellular level of Folate.
It gets complicated too because serum B12 and folate can be deficient even when the readings are normal or high. This is why it is important to get the cellular readings.
Treatment
Treatment is different for everyone depending on the severity of your deficiency, genetic factors need to be taken into account too and any other factors like the type of B12, dosage and form available where you live. For me, I am currently taking 2000mcg sublingual methylcobalamin divided into 1000mcg twice a day. I have been on this treatment for 9 weeks. I am getting better and have been feeling much better since about the 6 week mark. I still get brain vibrations but only in short waves mostly in the morning and then in the late evening when the B12 has worn off. No other symptoms remain. I am co-treating my iron deficiency with 29mg of Iron bisglycinate and 1000mg of buffered vitamin C for absorption every alternate day. At 12 weeks I get blood tests done again to check the progress. It can take months to come right. (more on iron deficiency in another article). In my case, I have struggled with iron deficiency for 25 years and this did not resolve on a gluten-free diet. It is my theory that my gut is just too damaged as other nutrients remain a problem too, such as vitamin D, calcium and B12.
Don’t skip your blood tests!
My experience and the research shows the importance of going for regular blood tests with celiac disease. You should get a full panel done at least once a year that also includes metabolic markers such as lipids, glucose, thyroid, liver and kidney function. Other tests include Calcium, Vitamin D, zinc, magnesium, copper,B12 (MMA as well if you can), RBC folate, Iron studies with ferritin and homocysteine.
research:
- Lamjadli S, Oujamaa I, Souli I, Eddehbi FE, Lakhouaja N, M’raouni B, Salami A, Guennouni M, Belghali MY, Hazime R, Admou B. Micronutrient deficiencies in patients with celiac disease: A systematic review and meta-analysis. Int J Immunopathol Pharmacol. 2025 Jan-Dec;39:3946320241313426. doi: 10.1177/03946320241313426. PMID: 39959924; PMCID: PMC11831651.
- Ghunaim M, Seedi A, Alnuman D, Aljohani S, Aljuhani N, Almourai M, Alsuhaymi S. Impact of a Gluten-Free Diet in Adults With Celiac Disease: Nutritional Deficiencies and Challenges. Cureus. 2024 Dec 2;16(12):e74983. doi: 10.7759/cureus.74983. PMID: 39744258; PMCID: PMC11692684.
- Kreutz JM, Adriaanse MPM, van der Ploeg EMC, Vreugdenhil ACE. Narrative Review: Nutrient Deficiencies in Adults and Children with Treated and Untreated Celiac Disease. Nutrients. 2020 Feb 15;12(2):500. doi: 10.3390/nu12020500. PMID: 32075276; PMCID: PMC7071237.
- Jivraj A, Connan V, Balart T, Ching E, Marwaha A, Verdu E, Armstrong D, Pinto-Sanchez MI. A23 NUTRITIONAL DEFICIENCIES ARE FREQUENT IN CELIAC PATIENTS ON A GLUTEN-FREE DIET, REGARDLESS OF THE DURATION AND COMPLIANCE OF THE DIET. J Can Assoc Gastroenterol. 2020 Feb;3(Suppl 1):27–8. doi: 10.1093/jcag/gwz047.022. Epub 2020 Feb 26. PMCID: PMC7043605.
- Bando T, Tokuda M, Katsuda I, Emi N, Tomita A. Involvement of folate and vitamin B12 deficiency in patients with normocytic anemia. Fujita Med J. 2023 May;9(2):134-141. doi: 10.20407/fmj.2022-016. Epub 2022 Oct 28. PMID: 37234385; PMCID: PMC10206897.
- Fernández-Bañares F, Beltrán B, Salas A, Comino I, Ballester-Clau R, Ferrer C, Molina-Infante J, Rosinach M, Modolell I, Rodríguez-Moranta F, Arau B, Segura V, Fernández-Salazar L, Santolaria S, Esteve M, Sousa C; CADER study group. Persistent Villous Atrophy in De Novo Adult Patients With Celiac Disease and Strict Control of Gluten-Free Diet Adherence: A Multicenter Prospective Study (CADER Study). Am J Gastroenterol. 2021 May 1;116(5):1036-1043. doi: 10.14309/ajg.0000000000001139. PMID: 33491958